Avocados and Frost in Europe (plus info on the cold-hardiest avocados and how to grow them)

The stem that died back

Judy Heald wrote:We live in Cornwall (the most South and west point) in the uk/ England. So it's as mild as I think you get in the UK?
...the avocado stem (that's mostly died off) is about an inch thick.

Great to see another person from the UK on this thread - there are not many of us here .  I'm not surprised that most of your avocado tree, at the base of your fig tree, died. Avocados are thirsty plants, figs are drought resistant - not a good mix - the fig would have robbed the avocado of sufficient soil moisture to maintain healthy growth.  

I'd really encourage you to have another go, Judy. Getting hold of some of the Mexican varieties (some can be very cold-hardy) would be best, but realistically it's not easy to find a bona-fide   source of such seed, from where we are. Importing plants is more difficult now with Brexit regulations and one nursery in SE England no longer imports grafted avocado plants, due to the risk of spreading the Xylella disease from Europe.

The other option is of course seed from supermarket-bought fruit. 'Bacon' or 'Fuerte' are probably best, as they're a bit more cold tolerant than 'Hass' and worth a try. One of my trees is a 'Hass' - it's 6 years old now - if it can grow here in SE England, it would probably thrive in the SW...  

Temperature-wise, you're probably in the best part of the U.K. for growing avocados -  I can't see why you wouldn't be successful in raising plants  from some supermarket-bought seed and growing them in the ground outdoors.  However, you will need a sheltered spot  away from coastal gales - it's a bit windy down your end! You will also need to protect them for their first three winters outdoors. The blogs I've written are full of details on how to do this successfully.

Best of luck!

Hi,

Is it normal for a mexicola avocado tree to have flower buds in october ? My young grafted plant got these buds this month. Last time, I got flower buds for the first time on the same tree in february this year.

Thanks,

Priyanshu

Priyanshu Uniyal wrote:Hi,

Is it normal for a mexicola avocado tree to have flower buds in october ? My young grafted plant got these buds this month. Last time, I got flower buds for the first time on the same tree in february this year.

Thanks,

Priyanshu

It is not really "normal," but I've had a couple that flowered a bit in fall. Typically, flowering is triggered by cool temperatures followed by warmth and ample water, so that usually happens in late winter or early spring. But my "Walter Hole" graft in my greenhouse looks like it's starting to expand flower buds now, even though it did also flower in spring this year.

Is yours indoors? Indoor trees may flower almost any time of year.

Thanks @mike guys !
We will soon have a big glass house on the south of our house. Everyone iv spoke to (who iv told enthusiastically "I'm going to grow avocados in it") have looked at me empathetically and said "good luck with that!"
I just know it's going to be possible! (Maybe with a rocket mass heater as my secret weapon.) But I just know I'm going to manage it. Especially after seeing this one still surviving when it's stem is pretty much fused to the fig!
It's so weird, as it's this seedling that's doing the best. Some how the cover and tiny micro climet the fig coving gives it has kept it doing better than the rest, although the fig will be it's demise sooner or later.

Winn Sawyer wrote:
Is yours indoors? Indoor trees may flower almost any time of year.

Thanks for your message. No, It is in a sunny place on my balcony. If I remember well, last time when I brought it inside was from mid-january to early april this year to protect it from freezing temperature. I live in Parisian region in France. Got some high fluctuating temperatures here since late september. Will flowers survive freezing weather ?

Priyanshu Uniyal wrote: Will flowers survive freezing weather ?

No.  Neither will fruit, as far as I'm aware.

Mike Guye wrote:

Priyanshu Uniyal wrote: Will flowers survive freezing weather ?

No.  Neither will fruit, as far as I'm aware.

Mature fruit (i.e. , fruit from flowers the previous winter/spring, almost ripe) of Mexican and even some hybrid varieties do fine in northern California with mildly freezing weather, probably even down to -2°C, but below that you get blackened hard patches on the fruit, especially exposed fruit. On the other hand, new fruitlets, freshly set in late winter will be zapped by even a mild freeze at that time. So the same would presumably be true of any foolhardy flowers that set fruit in fall.

Here's my Walter Hole graft, with the flower buds nearing the point of no return, but hopefully they stall and wait for the end of winter to actually open:

Henry Jabel wrote:I picked up 11 bacon avocados the other day . Can barter/share some of these with U.K peeps. If you are interested PM me.

Hi Henry, around 11 months ago you posted the above message, which was indeed great news !  I've only ever seen 'Bacon' fruit on sale here (St Leonards-on-Sea)  on one occasion.  I'm just wondering how your 'Bacons' are doing now.  Mine are now ~2 years old and appear to be doing well (planted in the ground outdoors) ...

Mike Guye wrote:

Henry Jabel wrote:I picked up 11 bacon avocados the other day . Can barter/share some of these with U.K peeps. If you are interested PM me.

Hi Henry, around 11 months ago you posted the above message, which was indeed great news !  I've only ever seen 'Bacon' fruit on sale here (St Leonards-on-Sea)  on one occasion.  I'm just wondering how your 'Bacons' are doing now.  Mine are now ~2 years old and appear to be doing well (planted in the ground outdoors) ...

Last winter we had some snow around Christmas then it was mild and then very dry for winter and then wallop the cold that wasn't actually that cold came along and killed everything including the stuff that was undercover. Wasn't just the avocados I had loads of things die on me, all my Chilean guava are dead (these had  established for around 7 years here surviving as cold as -7C here before), lots of hebes and quite of bit of newly planted English lavender died elsewhere too.    Lack of moisture in the air and snow cover probably didn't help but also we had a dry summer and after learning more about soil science this year and how arbuscular mycorrhizal fungi can help with cold for some of these plants, perhaps some of that fungi might of senesced and didn't recover to help the plants in time. So from now on everything is getting amf, biochar and bokashi to prevent that sort of thing happening again!

I have couple of new plants left but I lost track of what they are after all that I think one is a Bacon and Fuerte though. The worst was losing those very cold hardy imported Lilas they were looking pretty good before that.

Henry Jabel wrote:
... wasn't just the avocados I had loads of things die on me, all my Chilean guava are dead (these had  established for around 7 years here surviving as cold as -7C here before), lots of hebes and quite of bit of newly planted English lavender died elsewhere too ...    

That's terrible Henry - to say that you must have been utterly & totally gutted sounds pretty trite, I know, but I feel your pain. As gardeners we do get attached to our plants - they become like members of the family and to lose them is painful, given the hours of nurture, etc.

I remember on BBC TV's Gardeners World (2023) that presenter Monty Don's potted Citrus trees had been totally clobbered by the cold in winter 2022/23 in his garden in Herefordshire, even though they were sheltered inside a garden shed: temperatures hit -17 C.   There isn't much you can do when temperatures get that cold for a sustained period of time. And, as you mentioned, the freezing of the soil around the roots would have also in induced a drought stress for the evergreen plants, adding to any cold-injury already incurred,  since water uptake would have been impeded at a time of continued water loss from the leaves.

Arbuscular mycorrhizae, or mycorrhizae generally, are truly fascinating! Sometimes nick-named the "wood-wide-web", or the the "trees' social network", via which nutrients and metabolites are shared between trees (and non-woody plant species too), often providing communication / protection even between very different plant species or groups. With this in mind, I like to use a mycorrhizal dip when planting bare root trees, and use the minimum planting distance between individuals to favour this type of  root communication.  I haven't used such a dip for my avocado trees, when transplanting them to their outdoor in-ground position, but I'm pretty sure they have healthy root mycorrhizae as I'm constantly mulching the trees with organic matter (crop waste), all year round. The decaying crop waste will feed mycorrhizae and allow them to proliferate as well as increasing earthworm numbers and activity. All great for enhancing overall soil-fertility.  I do wonder whether the survival of my almost 7-year-old unprotected 'Hass' tree is due to the close proximity of the slightly more cold-hardy 'Fuerte', planted only 2 metres away from it to favour 'root communication'...

Henry, in future to protect your soil from freezing solid in winter and thereby protect surface roots & microorganisms associated with them, could you not mulch to provide a protective barrier for the soil? It might make a significant difference.

Thought you all might like this in this thread. Happy and thriving Bacon avocado at -4C, with nightly hard frosts and totally frozen ground, at 600m altitude in the mountains of Central North Portugal.

It's up against a granite well house, with a little stone wall built up around the bottom of the tree as well to serve as thermal mass. There is a little bit of warm goat manure and straw compost near the base of the tree (not touching stem) and around the stem is also insulated with a year's worth of brushed out thick undercoat fur from my Newfoundland dog - super cosy!

Rudyard Blake wrote: ... thriving Bacon avocado at -4C, with nightly hard frosts and totally frozen ground, at 600m altitude in the mountains of Central North Portugal ... It's up against a granite well house, with a little stone wall built up around the bottom of the tree as well to serve as thermal mass.

Is it a south-facing wall?
Is it a grafted Bacon?

It's great Rudyard that you seem to have got such a lovely sheltered spot, which I'm sure has 'saved your Bacon' - pardon the deliberate pun which I couldn't resist! Though I can see frost on the vegetation around the tree, I'm taking a guess that the soil by the wall, where the avocado is rooted, is not frozen. As far as I know, grafted Bacon is good down to around -5C air temperature.

For comparison, it'd be worth putting a max/min thermometer in the shelter of that wall and another in the surrounding more exposed [colder] areas, just to see how much protection that wall is actually giving ...

Mike Guye wrote:

Rudyard Blake wrote: ... thriving Bacon avocado at -4C, with nightly hard frosts and totally frozen ground, at 600m altitude in the mountains of Central North Portugal ... It's up against a granite well house, with a little stone wall built up around the bottom of the tree as well to serve as thermal mass.

Is it a south-facing wall?
Is it a grafted Bacon?

It's great Rudyard that you seem to have got such a lovely sheltered spot, which I'm sure has 'saved your Bacon' - pardon the deliberate pun which I couldn't resist! Though I can see frost on the vegetation around the tree, I'm taking a guess that the soil by the wall, where the avocado is rooted, is not frozen. As far as I know, grafted Bacon is good down to around -5C air temperature.

For comparison, it'd be worth putting a max/min thermometer in the shelter of that wall and another in the surrounding more exposed [colder] areas, just to see how much protection that wall is actually giving ...

The wall is West facing and it actually only gets a few hours of sun this time of year! I planted it there because I hoped the thermal mass from the granite blocks in the well house would help it in winter and also because that side of the garden stays damp in the summer, because it's surrounded by rather high walls that keep the ground shaded a bit more so it doesn't all evaporate. This time of year though the high walls eclipse the sun almost all of the day.

I'm not sure if it's grafted, I'll have to check and see if I can see a graft. The guy in the market where I got it from said it's adapted to the local climate.

I'm not sure how much the ground was frozen right there when I took this pic -this was taken in December; I know that there was a frozen crust when I was digging in the vegetable beds over on the sunny side of the garden, but perhaps the warm compost and dog wool protected the soil under the tree?

I'm actually amazed how happy it seems. The leaves are basically perfect - they look so much better than all the indoor avos I grew in the UK, which tended to get crispy brown edges.

Rudyard Blake wrote: I'm actually amazed how happy it seems. The leaves are basically perfect - they look so much better than all the indoor avos I grew in the UK, which tended to get crispy brown edges.

It's true Rudyard, your Bacon looks very happy there!  
It seems to me that, apart from freezing temperatures, winter gales, and poor drainage around the roots in winter, avos always seem to be happiest when planted permanently in the ground outdoors - there appear to be a number of reasons for this.

We had two days of harder frost recently, down to minus 7 in some places. I did decide to only protect the fantastic seedling during the two days and not the mexicola seedling, that freezes down to it's roots every winter, because the fantastic seedling is the first one i ever had to grow back from the stem outdoors after a winter outside with little to no protection.
Pictures of burnt mexicola, fantastic seedling that was protected and two closeups of where it grew back from the stem which for me in itself is a tiny victory.

Here's a quick update on the 'avocado orchard', here in SE England (plant age in brackets) - all plants raised from seed (not grafted).

MEXICAN TYPES:
In nursery ......................  Del Rio (18 months), Daughter, Joey & Wilma (all 3 months)
In-ground outdoors ....... Fuerte (5 years, but razed to ground at 2 years, recovered, and doing well for the last 3 years)

GUATEMALAN TYPES:
In-ground outdoors........Hass (~7 years), Bacon x 4 (2 years)

GENERAL OBSERVATIONS
All are making good progress.  All are single plants except Bacon (4 plants).
Hass hasn't  had any winter protection for the last 3 years as the tree is too big to make this practical, though it's always pruned hard once a year (in spring) to keep its height below 2.5 metres.  A very vigorous tree. During this winter (2023/24) and the last (2022/23), it suffered the most winter damage due to unusually cold weather. Nevertheless it showed remarkable recovery in spring last year and flowered for the first time. It's expected to show winter recovery again in spring 2024.  

For the first 3 years plants are always protected, when air temperatures fall below 0°C, with 3 to 4 layers of horticultural fleece. If you don't do this you will lose plants - I can't emphasize this enough. Consequently, during periods of cooler winter weather, I follow the local area weather forecast on a daily basis to alert me in advance of when the plants need covering.

Like with some of the more frost-hardy citrus, hardiness develops with age, young trees being very vulnerable, even to light frosts. The fleece I use is a 'breathable' type to prevent condensation, and has a 'thickness' of 60gsm (gsm = grams per square metre). I've found that during cold spells, where night temps fall below 0°C, breathable fleece covers can be left on plants continuously, for up to 2 weeks, without any ill-effect.  The covers can probably be left on for longer but I haven't yet tried this, as to we don't appear to have freezing weather that persists beyond 2 weeks.  'Non-breathable' covers, which are cheaper and I've tried in the past, drip condensation in cold weather which can lead to the decay of leaves and stems, particularly those parts that have become frost-damaged,  if they're left on for any significant length of time.

Mike Guye wrote:Here's a quick update on the 'avocado orchard', here in SE England (plant age in brackets) - all plants raised from seed (not grafted).

MEXICAN TYPES:
In nursery ......................  Del Rio (18 months), Daughter, Joey & Wilma (all 3 months)
In-ground outdoors ....... Fuerte (5 years, but razed to ground at 2 years, recovered, and doing well for the last 3 years)

GUATEMALAN TYPES:
In-ground outdoors........Hass (~7 years), Bacon x 4 (2 years)

GENERAL OBSERVATIONS
All are making good progress.  All are single plants except Bacon (4 plants).
Hass hasn't  had any winter protection for the last 3 years as the tree is too big to make this practical, though it's always pruned hard once a year (in spring) to keep its height below 2.5 metres.  A very vigorous tree. During this winter (2023/24) and the last (2022/23), it suffered the most winter damage due to unusually cold weather. Nevertheless it showed remarkable recovery in spring last year and flowered for the first time. It's expected to show winter recovery again in spring 2024.  

For the first 3 years plants are always protected, when air temperatures fall below 0°C, with 3 to 4 layers of horticultural fleece. If you don't do this you will lose plants - I can't emphasize this enough. Consequently, during periods of cooler winter weather, I follow the local area weather forecast on a daily basis to alert me in advance of when the plants need covering.

Like with some of the more frost-hardy citrus, hardiness develops with age, young trees being very vulnerable, even to light frosts. The fleece I use is a 'breathable' type to prevent condensation, and has a 'thickness' of 60gsm (gsm = grams per square metre). I've found that during cold spells, where night temps fall below 0°C, breathable fleece covers can be left on plants continuously, for up to 2 weeks, without any ill-effect.  The covers can probably be left on for longer but I haven't yet tried this, as to we don't appear to have freezing weather that persists beyond 2 weeks.  'Non-breathable' covers, which are cheaper and I've tried in the past, drip condensation in cold weather which can lead to the decay of leaves and stems, particularly those parts that have become frost-damaged,  if they're left on for any significant length of time.

Thanks for the updates, Mike. I really appreciate your detailed observations as there is very little information about growing avocados in our climate. What's the coldest temperature you've recorded so far this winter?

I want to try experimenting with planting an avocado in my garden this year and I plan to protect it in a similar way to how I have protected my 'Orogrande' Clementine tree this year. I put some old-style incandescent lights around it and then put a plant fleece bag over it during cold spells. I then remove the bag to allow better airflow and turn off the lights after the chance of frost has gone. I even have a tiny lychee seedling planted under it too, which was purely done as a bit of fun, but it is surprisingly still alive. I recently shared a video of how it was doing on my YouTube channel here. I think this technique could also be employed with avocados (and possibly other borderline plants).

A few days ago I went down to London for a work event and while I was down there I met up with some friends who are also really into growing tropical and subtropical plants. We had a look at the large avocado tree in Southwark. It seems like it has had some large sections removed and possibly suffered from some damage during one of the storms. Nevertheless, it still has quite a lot of avocados on it and it appears that it might be preparing to flower again soon. We were fortunate to be able to take some cuttings (with permission) that I have since attempted to graft onto some seedling avocados. I have also got a couple of other plants that I grafted back in September from the same tree that a friend posted up to me.

Here is a short video of my visit for anyone interested:


We also visited the Chelsea Physic garden which also has a large fruiting avocado tree, I will hopefully post a video of that tree in the coming week.

Peter Entwistle wrote:still has quite a lot of avocados on it and it appears that it might be preparing to flower again soon

The fact that it's still holding fruit at this time of year is further confirmation that it's a Guatemalan type, as Mexican avocados would mostly have finished and dropped by this time. Not that there was really any doubt about that.

I strongly suspect that any grafts of that tree that are grown in a less favorable microclimate will be damaged most winters, similar to Mike's large Hass seedling tree. Not that I'm discouraging anyone who's propagating it, since it's definitely now a piece of avocado zone-pushing history, and worth sharing for that reason alone, even if it's not particularly cold-hardy.

Peter Entwistle wrote: What's the coldest temperature you've recorded so far this winter?

Unfortunately,  I wont be able to answer that question with any precision until June 2024.

I have a standalone field datalogger recording temperatures continuously, around the avocado trees, for the period 1 Nov 2023 - 31 May 2024. I wont be analyzing its data until June, but will post the numbers then on my imgur avocado blogs. I suspect the 'lows' so far have been fairly similar to last winter: entry no.8 at  https://imgur.com/a/FmRvs7d should give you a rough idea.

It's probably significantly milder temperature-wise down here, compared to your location in the NW, though the frequent winter coastal gales, on our exposed site, would appear to be a major cause of  winter damage, accentuating any damage already incurred by freezing temperatures.

Do post any progress you make with the scions taken from the famous 'Southwark Tree'.  I agree with Winn's comments that it's more than likely to be a favourable microclimate that has allowed that tree to thrive in London, rather than any genes expressing enhanced cold tolerance.  

Winn Sawyer wrote:I strongly suspect that any grafts of that tree that are grown in a less favorable microclimate will be damaged most winters, similar to Mike's large Hass seedling tree. Not that I'm discouraging anyone who's propagating it, since it's definitely now a piece of avocado zone-pushing history, and worth sharing for that reason alone, even if it's not particularly cold-hardy.

Yes, I am pretty convinced it is just a Hass seedling. The leaves also didn’t really have any kind of scent when I crushed them, which Mexican types should have. I have been told that this tree has suffered significant damage in colder winters, especially when it was younger. But you are right it is very unlikely to survive outside of a sheltered microclimate similar to the one it is growing in. I am mostly interested in preserving its genetics, as it is such a special tree for us here, but of course, getting hold of mature, avocado budwood in the UK is virtually impossible. So my hope is that if I can provide protection during cold spells, as I have done with my Clementine tree, which I posted above, it should provide enough protection to prevent it from being damaged. In any case, it will be an interesting experiment to document, even if it results in failure. Also like Mike mentioned in a previous post, avocados tend to get more cold-tolerant as they age. So hopefully after a few years of providing it with protection, it won’t be quite as vulnerable during any cold spells.

We have been fairly lucky (so far) with winter here. Although we did get some very cold temperatures and frost here in December and January it only lasted a few days each time, so most of the time my clementine has not been covered.

Mike Guye wrote:Unfortunately,  I wont be able to answer that question with any precision until June 2024.

I have a standalone field datalogger recording temperatures continuously, around the avocado trees, for the period 1 Nov 2023 - 31 May 2024. I wont be analyzing its data until June, but will post the numbers then on my imgur avocado blogs. I suspect the 'lows' so far have been fairly similar to last winter: entry no.8 at  https://imgur.com/a/FmRvs7d should give you a rough idea.

It's probably significantly milder temperature-wise down here, compared to your location in the NW, though the frequent winter coastal gales, on our exposed site, would appear to be a major cause of  winter damage, accentuating any damage already incurred by freezing temperatures.

Do post any progress you make with the scions taken from the famous 'Southwark Tree'.  I agree with Winn's comments that it's more than likely to be a favourable microclimate that has allowed that tree to thrive in London, rather than any genes expressing enhanced cold tolerance.

Yeah, we have reached the low you got last year several times in December and January and likely a few degrees cooler too. I don't have a thermometer in my garden, so I can only go off the weather forecast, but yeah we are definitely cooler up here. That being said I think planting right next to a brick wall will be my best option and of course, in my garden, it is relatively easy for me to provide a heat source if it gets very cold, which I certainly couldn't do on my allotment.

I will definitely keep everyone updated on how the grafts get on.

Peter Entwistle wrote:
I don't have a thermometer in my garden, so I can only go off the weather forecast, but yeah we are definitely cooler up here. That being said I think planting right next to a brick wall will be my best option

For next winter could you put a max/min thermometer next to the brick wall (but not touching), level with the top of your tree, to get an idea of the actual temp minima in that specific spot?

For next winter, I think I'll put a max/min thermometer next to my trees, just to get a rough idea of the temperature minima the field dataloggers are detecting. Waiting until June each year, to analyse the dataloggers, is always too long to wait!  I find that our site location (N-facing slope) is often colder than the local area weather forecast's prediction, and even within the site there is significant temperature variation.

Peter Entwistle wrote:
I will definitely keep everyone updated on how the grafts get on.

Thanks Peter.

It's quite likely that I'll be giving away (for free) 3 out of the 4 remaining 'Bacon' trees that I've got growing outdoors (see attached photo).  If you're interested, please use the permies mail to let me know (don't post here on the forum).  I'm giving them away as I  want to keep only one individual of each 'variety', due to a limitation on space.

These trees are only available to UK residents (you'll need to provide your own transport), due to the complicated administration & costs involved in exporting live plant material with soil.  I'll contact anyone interested around April time (spring is the best time for transplanting), to arrange collection.

If you want further detailed information on this plant material, see entries (18) & (19) at https://imgur.com/a/FmRvs7d  
I'll be keeping 'Bacon-2' (2nd from the left in the photo), but giving away the 3 others.

Mike Guye wrote:
For next winter could you put a max/min thermometer next to the brick wall (but not touching), level with the top of your tree, to get an idea of the actual temp minima in that specific spot?

For next winter, I think I'll put a max/min thermometer next to my trees, just to get a rough idea of the temperature minima the field dataloggers are detecting. Waiting until June each year, to analyse the dataloggers, is always too long to wait!  I find that our site location (N-facing slope) is often colder than the local area weather forecast's prediction, and even within the site there is significant temperature variation.

Yes, I definitely plan to get some thermometers set up around the garden. I know from using an infrared thermometer that the area next to the wall does seem to stay a few degrees warmer on cold nights. But I would like to get some wireless thermometers that could send the data in real-time and perhaps even set it up to display on my website (but that's probably going to be way down the line though).

Mike Guye wrote:
It's quite likely that I'll be giving away (for free) 3 out of the 4 remaining 'Bacon' trees that I've got growing outdoors (see attached photo).  If you're interested, please use the permies mail to let me know (don't post here on the forum).  I'm giving them away as I  want to keep only one individual of each 'variety', due to a limitation on space.

These trees are only available to UK residents (you'll need to provide your own transport), due to the complicated administration & costs involved in exporting live plant material with soil.  I'll contact anyone interested around April time (spring is the best time for transplanting), to arrange collection.

That's very good of you to offer those, Mike. If I lived nearby I would have definitely taken you up on that offer.

Oh, I thought it was also worth mentioning here that the nursery Plants4Presents has listed some avocado trees for sale recently. They state that they are grafted, but don't provide any details about the variety. I contacted them but they basically told me that they won't be able to provide any more information until they receive the plants from their supplier. I decided to order a couple anyway as they are rarely offered for sale here. If they turn out to be grafted but not labelled, it's likely they will be a Hass or perhaps one of the other common varieties grown in the Mediterranean such as Bacon or Fuerte etc.

Peter Entwistle wrote:
But I would like to get some wireless thermometers that could send the data in real-time and perhaps even set it up to display on my website (but that's probably going to be way down the line though).

I have a DIY setup for that, using Raspberry Pi Zero W computers with thermometer chips plugged into their GPIO headers. It would require a wifi signal and some type of waterproof case, but I'd be happy to share the hardware design that I use, and the (pretty simple) python code for sending the temperature to a website, as well as the (pretty simple) PHP code on the website that receives the measurements loads them into an SQL database.

In fact, the most complicated part is the javascript code for displaying the data, which uses the Chart.js library, but that should be pretty easy to copy and tweak.

You can see the end result here with a few options for the time series, though only registered members can create custom time series:

https://www.drymifolia.org/data.php

It might be a little off-topic to discuss that here in much depth, but if there's enough interest I could start a new thread in an appropriate section on here.

Winn Sawyer wrote:
I have a DIY setup for that, using Raspberry Pi Zero W computers with thermometer chips plugged into their GPIO headers. It would require a wifi signal and some type of waterproof case, but I'd be happy to share the hardware design that I use, and the (pretty simple) python code for sending the temperature to a website, as well as the (pretty simple) PHP code on the website that receives the measurements loads them into an SQL database.

In fact, the most complicated part is the javascript code for displaying the data, which uses the Chart.js library, but that should be pretty easy to copy and tweak.

You can see the end result here with a few options for the time series, though only registered members can create custom time series:

https://www.drymifolia.org/data.php

It might be a little off-topic to discuss that here in much depth, but if there's enough interest I could start a new thread in an appropriate section on here.

That would be very interesting to see, I was considering using a Raspberry Pi, or Arduino. I am actually a software engineer, so I do like tinkering with stuff like that, although I'm not so good at the hardware side, so I would be interested to see more detail on that.
Please let me know if you start a new thread.

Peter Entwistle wrote:
That would be very interesting to see, I was considering using a Raspberry Pi, or Arduino. I am actually a software engineer, so I do like tinkering with stuff like that, although I'm not so good at the hardware side, so I would be interested to see more detail on that.
Please let me know if you start a new thread.

I started a thread here, but I didn't get very far in the tutorial before my toddler woke up and demanded my attention, so I'll have to finish it another time:

https://permies.com/t/241793/DIY-temperature-logging-raspberry-pi

Mike Guye wrote:It's quite likely that I'll be giving away (for free) 3 out of the 4 remaining 'Bacon' trees that I've got growing outdoors (see attached photo).  If you're interested, please use the permies mail to let me know (don't post here on the forum).  I'm giving them away as I  want to keep only one individual of each 'variety', due to a limitation on space.

These trees are only available to UK residents (you'll need to provide your own transport), due to the complicated administration & costs involved in exporting live plant material with soil.  I'll contact anyone interested around April time (spring is the best time for transplanting), to arrange collection.

If you want further detailed information on this plant material, see entries (18) & (19) at https://imgur.com/a/FmRvs7d  
I'll be keeping 'Bacon-2' (2nd from the left in the photo), but giving away the 3 others.

Hi Mike,
Regarding your avocado plant growing experiment I have sent you a 'purple mooseage' here on the forum as I don't have your actual e-mail address of course,
Kind regards,
Brett

Hello, I know this is an old thread. However, I wanted to add  young tree avocados die with a slight frost! I'm in south of France with lovely warm summers, but the weather is wet and cold for 4-6months.... I lost 50 trees in a slight frost! Never again.... If there is a slight frost where the trees will physically be, no matter what country. They will not last long.....

Mkl Swift wrote:Hello, I know this is an old thread. However, I wanted to add  young tree avocados die with a slight frost! I'm in south of France with lovely warm summers, but the weather is wet and cold for 4-6months.... I lost 50 trees in a slight frost! Never again.... If there is a slight frost where the trees will physically be, no matter what country. They will not last long.....

What varieties of Avocado were these? And what was temperature? Asking as I am in similar climate zone - The Netherlands.

Marco Swif wrote:Hello, I know this is an old thread. However, I wanted to add  young tree avocados die with a slight frost! I'm in south of France with lovely warm summers, but the weather is wet and cold for 4-6months.... I lost 50 trees in a slight frost! Never again.... If there is a slight frost where the trees will physically be, no matter what country. They will not last long.....

What you report is well known.  
The most difficult stage is the first three years of the tree's life: you will need to protect them from any frost for at least the first 3 winters. I have already given loads of detailed advice on this (scroll back and click on my 'imgur links'). You will need good drainage around the root system, particularly important in the cold wet winters you mention: ideally plant them on sloping land, or on a wide ridge  or mound.  My advice is if you try this experiment again, make it manageable for yourself - 50 trees sounds far too much to begin with !  Start with say 2 or 3 trees so that looking after them during the winter is manageable. Success with this will encourage you to take on more trees later on.

Mike Guye wrote:

Marco Swif wrote:Hello, I know this is an old thread. However, I wanted to add  young tree avocados die with a slight frost! I'm in south of France with lovely warm summers, but the weather is wet and cold for 4-6months.... I lost 50 trees in a slight frost! Never again.... If there is a slight frost where the trees will physically be, no matter what country. They will not last long.....

What you report is well known.  
The most difficult stage is the first three years of the tree's life: you will need to protect them from any frost for at least the first 3 winters. I have already given loads of detailed advice on this (scroll back and click on my 'imgur links'). You will need good drainage around the root system, particularly important in the cold wet winters you mention: ideally plant them on sloping land, or on a wide ridge  or mound.  My advice is if you try this experiment again, make it manageable for yourself - 50 trees sounds far too much to begin with !  Start with say 2 or 3 trees so that looking after them during the winter is manageable. Success with this will encourage you to take on more trees later on.

Hi Mike, is building a mound by incorporating big lava stones (in bottom part) and planting avocado tree/s on top of it will be a good idea? Asking as in The Netherlands everything flat and we do have heavy raining seasons.

Sergey Erlikh wrote: Hi Mike, is building a mound by incorporating big lava stones (in bottom part) and planting avocado tree/s on top of it will be a good idea? Asking as in The Netherlands everything flat and we do have heavy raining seasons.

I wouldn't plant your avocado on a heap of stones/rocks covered in soil - you need a good depth of good quality soil with a thick layer of organic matter (mulch) on the soil surface to keep in the moisture and improve the soil as it breaks down.  I think the set-up you're proposing would dry out too quickly in summer. Avocados need watering regularly during the growing season - they get quite thirsty in hot weather, e.g. I give my 2-3 year old trees (~2 metres height) around 40 litres per tree at any given watering.

If you have the space you could make your mound by simply by raking soil in from a wide area. However, this might not be possible where you are, e.g. only a very small planting bed available. You would need to make sure the mound is compacted a bit before planting.  I have the luxury that I'm on a sloping site so it's  naturally well-drained.

I planted this avocado tree in the ground in my garden earlier today. It was purchased as a 'grafted' avocado tree, but it turned out not to be grafted, unfortunately. Based on the strong scent of liquorice I get when I crush the leaves, I would guess it's a seedling of a Mexican avocado type. Of course, there's no way to know for sure which avocado it’s from. I planted it in a mound in the border in front of a brick wall in a southwest-facing position. Half of the root ball is above grade, to hopefully help prevent root rot. The soil in my garden does seem to drain pretty well, so hopefully, it will be fine. I plan to protect it in a similar way to my clementine tree over winter, which I showed in a previous post. That method worked out really well last winter, so I don't see why it wouldn't work for an avocado. I may graft some named varieties onto it in the future, as it will likely take a very long time to produce since it's just a seedling. I will post a video later in the week to show it in more detail.

I also have another avocado tree from the same source, as well as a grafted 'Fuerte' avocado that I have growing in my greenhouse, although the one I have outside has done better. I think it's been too dry, and I haven't been watering the pots enough inside the greenhouse. I'm also growing a number of seedlings from both Hass and Bacon avocados, which will be overwintered indoors. I'll do a separate post and update video on my YouTube channel about the London avocado grafts I did (now known as the 'Julienne' variety).

Haha definitely completely potty Peter but I look forward to seeing the full YouTube video. Of course as you said, if you are going to grow it inside an enclosure with some sort of supplementary heating ( that's cheating haha ) there is no reason why it cant succeed although given how quickly they can grow it's likely to be challenging in the future 😁.
I may well decide to construct a shelter around the seedling I got from Mike Guye as I'm not sure I can fit it into my summerhouse lol

I have uploaded a video as I mentioned yesterday. We'll see how it goes over the winter, but hopefully, with some protection during the cold spells, it will make it. Of course, I will continue to give updates on how it gets on.

Brett Lyons wrote:I may well decide to construct a shelter around the seedling I got from Mike Guye as I'm not sure I can fit it into my summerhouse lol

Yeah, it's definitely worth trying something like that, Brett. I'm sure it will do well as it's got to a pretty decent size 👍

This year, I've been a bit delayed in getting my UK outdoor avocado-growing blogs up-to-date. However, Hass & Fuerte have now been updated, up until August 2024 (see links below).  There may be one more update in November, focusing on growth-rates towards the end of the growing season.

'Hass' (7-year-old tree)...    https://imgur.com/a/5gflnlU

'Fuerte' (5-year-old tree)... https://imgur.com/a/0XuODou

Blogs for 'Bacon', 'Del Rio', 'Daughter', 'Joey' and 'Wilma' are in the process of being updated and will post here when done.

Mike Guye wrote:This year, I've been a bit delayed in getting my UK outdoor avocado-growing blogs up-to-date. However, Hass & Fuerte have now been updated, up until August 2024 (see links below).  There may be one more update in November, focusing on growth-rates towards the end of the growing season.

Hass (7-year-old tree)...    https://imgur.com/a/5gflnlU

Fuerte (5-year-old tree)... https://imgur.com/a/0XuODou

Blogs for Bacon, Del Rio, Daughter, Joey and Wilma are in the process of being updated and will post here when done.

Wow, the Hass seedling has really thickened up nicely now, Mike! The Fuerte is also coming along really well too. I can't wait to see how all the others are doing.
That reminds me I need to get something to log the temperatures in my garden over winter, which I can place near my avocado (unknown Mexican type) and Clementine trees. Is there anything you would recommend, Mike? I guess I'd need to cover any thermometer with a Stevenson screen to have accurate daytime temperature readings.

Peter Entwistle wrote:
... that reminds me I need to get something to log the temperatures in my garden over winter, which I can place near my avocado (unknown Mexican type) and Clementine trees. Is there anything you would recommend, Mike? I guess I'd need to cover any thermometer with a Stevenson screen to have accurate daytime temperature readings.

Around 6 months ago (scroll back), you were considering using a Raspberry Pi or Arduino set-up for monitoring temperatures. Did you try that, following Winn's guidance for the Pi? I took the easier option, buying a datalogger and thermocouples  from  https://www.omega.co.uk, but you might get cheaper if you shop elsewhere as they seem expensive.

Yes, you're right you'll need to shield your thermocouple, if you want to accurately measure daytime air temperatures too, to avoid the direct heating-up effect of the sun on the temperature-sensor itself.   I don't use any sensor-shielding, as I'm only interested in temperature minima, which always seem to occur here during the hours of darkness.  Interestingly, I can always tell when the moment of dawn arrives, when looking at the graphed temperature data, as a small but abrupt jump in temperature (a jump of ~ 0.1ºC if I recall correctly)  seems to occur the moment the first rays of the sun hit the sensor. The thermocouple cable and sensor I use is  teflon-coated so it's waterproof/weatherproof. You can use them to measure soil temperatures too, as the teflon coating is just about resistant to anything. I use 4-wire PID thermocouples, probably overkill for what I'm using them for now with the avocado work, with an accuracy of around ±0.01ºC.