Luke Mitchell

gardener
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since Feb 04, 2020
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Biography
I manage a smallholding in Pembrokeshire, Wales with my partner. We have established a small coppice (mixed species, mostly hazel) and are growing edible mushrooms on hardwood logs. The majority of the land is managed as haymeadow, rich in wildflowers. We grow a large amount of food on our small, polycultural vegetable area with a focus on perennial and low-input varieties. The site is a haven for wildlife and we keep conservation in mind whenever we make changes.
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Recent posts by Luke Mitchell

Tony Wrench built his roundhouse up the road from where I live. The climate here is pretty mild, although it does get cold (for us) in the winters. I wouldn't expect to see negative numbers (-1C and below) for many days each winter though, and rarely below -6.

Straw bales are surprisingly good insulation. This thread here on Permies suggests that a single bale is around R28-R35, depending on its size and orientation. You could very easily double up on the straw bales, pegging them together with sharpened wooden stakes if you like, to achieve an R-value of 50 or more.

To add to this, the turf ("sod") layer will provide additional insulation. I don't have any figures to hand for that but it will be significant.

In terms of waterproofing, the EPDM/pond liner will want to be placed between the turf and the straw. Hopefully the reasons for this are obvious but the straw will fail very quickly if it is allowed to get wet.

The condensation issue might not be as severe as some imagine. The roof design would be described as a "warm roof", meaning that the insulation is on the inside and the cold, water impermeable layer beyond it. This means that there isn't a cold surface for the water vapour to condense on. Placing a vapour barrier between the straw and the rafters would remove any risk of water ingress but I would worry about the straw being unable to breath.

A final consideration is that Tony didn't have to consider large snow loads for his design. This will, of course, only add to the roof insulation but you should consider using larger timbers that he does to cope with the increased weight.
2 weeks ago
Hi Nancy,

I live in a big coffee-drinking household and we get through a lot. All of our spent grounds (once they have been used to make coffee) get composted straight in the heap, where they seem to do very well. We have picked up waste coffee from cafes too, as they often give away their grounds, but not so regularly.

It has been said that too much coffee in the compost will sour it (turn it acidic). I'm not sure how true that is and, certainly, it could be balanced out with some chalk/lime/wood ash (and our compost gets some the latter two).

I've also heard that slugs and snails don't like coffee grounds and will not crawl (slide?) over it if they can avoid doing so. I have tried to create rings of coffee grounds around sensitive plants but, to be honest, I've not noticed much of an effect.

A final thought is that it may be good for disguising plants for whom the pests discover by smell. Carrot root fly, for example, is famous for smelling out the carrots that it lays its larvae in and people often use a guild of aromatic plants, such as marigolds or garlic, alongside the carrots to discourage the fly. I wonder if coffee grounds in close proximity to carrots would help too?
2 months ago
This is a badge bit (BB) that is part of the PEP curriculum.  Completing this BB is part of getting the straw badge in Nest.

In this Badge Bit, you will make a broom. Broom bristles can be made from various different natural materials, such as "broom corn" (sorgum), branches (heather and birch branches are common, as are branches from the broom plant), weeds, or even fibres (like palm fibre). (More on the history of brooms can be found here and )

The bristles can be attached to the broom with various materials, from twine to string to wire.

This is a video on making a sorgum ("broom corn") broom with wire:



This one is made with branches (called a besom broom):



This one is made with palm fronds (note, it would need a handle):



This one is made from the ribs of coconut fronds (note, it would need a handle)



To complete this BB, the minimum requirements are:
   - must be made of untreated wood
   - must be sanded down to prevent splinters
   - must be oiled with a nontoxic oil (e.g. linseed oil)
   - must use natural fibers or materials on the broom head

To show you've completed this Badge Bit, you must provide proof of the following with pictures (or a video < 2 mins long):
   - before, during, and after of making a broom
   - demonstrate it meets the above stated requirements
3 months ago
I tried taking a load of cuttings in autumn last year but none of them took. I plunged them into the end of one of our vegetable beds and by the spring they had all succumbed to the frost. I would suggest trying to keep them somewhere sheltered and hopefully you'll have a better result.
3 months ago
Ulla, your squash look amazing as usual! I love the crooknecks.

I've not taken a serious venture into growing grains yet. There is a tradition of growing oats in my part of the world and I would like to try that at some point. I don't have the equipment that would make it viable at the moment though - I'd either need to shade off some of the grass for a year, till the soil to create a seedbed or, better, do both. I imagine (and hope) that I wouldn't need to till the soil each year and I can probably work out a rotation with legumes (broad beans!) to keep the soil healthy. That's a project for another year though.

Your sorghum looks great. Well done on getting such a good harvest.

As usual, the squash we are harvesting are taking over the house. Any flat surface has one on at the moment! I've attached a photo of our staircase for comedy value.
4 months ago
I keep forgetting to snap photographs when we are harvesting. We've pulled a load more beets, I'll have to remember this week when we are putting together the veg. boxes.

In the mean time, our French ('kidney') beans and some of the borlotti beans have started to dry on the plants and need harvesting. I've taken in about half of the ripe beans so far and they are drying in the kitchen. Some of the beans I'll save for seed, for next year. Most of them will be eaten over the winter.

I podded enough beans to fill a large pyrex mixing bowl, a little over 1kg. There are plenty more and I'd expect to yield somewhere closer to 2.5kg that I will dry and put away for storage. Over the summer we have eaten a lot of immature beans and their pods too. I'm hoping, next year, to grow about 5x as much as I really enjoy growing legumes.

We grow most of our beans as '2 sisters'. That is, we grow the beans up hazel poles, initially with lettuces or other short crops beneath them. Once the short crops have been harvested, the beans have climbed the poles and we can transplant our squash plants. The squash then cover the ground beneath the beans, protecting the soil and shading out most of the weeds.

One of our beds is true '3 sisters', with sweetcorn planted amongst the squash and beans. The corn has done pretty badly this year - it's slow and several of our plants were eaten early on - but the guild seems to work nicely, even in wet West Wales.

Kidney/French beans harvested: 1kg (3300kcals)

And that is species #11! Just a few more beets to go...
4 months ago
Hi Mark,

As someone who uses wood as one component of home heating, I feel rather threatened each time I read one of those "attack pieces" online. There are many reasons that I burn wood (in-cycle carbon; collected and processed by myself from our woodland; not dependent upon fossil fuels or other unknowns, beyond my sphere of influence) and I would hate for the emissions debate, which seems to be flaring up, to deprive me of that option.

I confess that I haven't got an air quality meter and so much of what I am about to type is mere conjecture, however, I do feel that using a decent quality stove (or RMH!) that is well-maintained and burning dry fuel has a pretty insignificant effect on indoor air quality.

I've lived in properties with open fires and the soot that gets everywhere is pretty good evidence that the air is full of carbon particulates. The only problem I see with my stove is the ash, which can escape during cleaning, and the soot generated when sweeping the chimney. I use a vacuum cleaner when both cleaning and sweeping to try and minimise these concerns.

I have also heard that opening the door to a sealed wood stove will suck some of the flue gasses into the living area. I've definitely seen a curl of smoke escape if I've opened the door too quickly. By gently cracking the door open and opening it slowly, after a moment of hesitation, I've found this to be avoidable.

With RMH, there often isn't a door to open and I don't feel this would be a concern. If the fuel is fed into an open fuel box then the draw into the flue pipe should be continuous - taking the particulates with it. The same should be true for open fires but I think the large, open area detracts from its ability to draw cleanly - most open fires I have known will puff smoke back into the living area when the wind blows hard outside, and often sporadically until the flue has warmed sufficiently when the fire is first lit.

This leads me to mention, again, proper maintenance and burning practices. If the flue/chimney is well swept (avoiding restriction of air flow), the fire is kept hot enough to full combust the fuel, the air vents open enough to allow the fuel to be fully burnt AND the fuel is of good quality to begin with, I feel that the in-house emissions would be much lower than the reported figures.

Maybe I should look for an air quality indicator and run some experiments...

I hope someone with more experience than me can chime in on RMHs.
4 months ago
I can't believe I haven't been posting our beets! They are a great, calorie-dense root and we have been growing them all season for our veg boxes.

This week we have over 3kg of beets. There has probably been the same every week for the past two months.

Beetroot harvested: 3kg (1290 kcals)

I'll add a few more photos when I remember and that should be species 11 in the bag...
4 months ago
Of course. The panels are here.

The specs are posted in "STC" (standard test conditions) and "NOCT" (nominal operating cell temperature). I used "STC".

ParameterValue
Vmpp31.42v
Impp13.05A
Voc37.4v
Isc13.84A
V temp coeff-0.265%/°C
I temp coeff+0.05%/°C


Plugging those values in again, I get 128.7v @ -30°C. I think I must have accidentally used a "NOCT" value for one or more parameters previously, which would explain the difference of 8v in my two numbers.

If you think I'm doing something wrong, please do let me know!
4 months ago

Mark Miner wrote: Going back to your question about crimping, it depends on how often you might do this. I have a $50 crimper from Amazon/China that has a rotary die at the tip, and can do from like 8awg to 0awg (but I have popped one at the high gauges, so really it tops out at 2awg or 4awg, and I use my hydraulic one above that).

I don't know how game you are to solder, but filling your crimped terminal will guarantee no relaxation over time, especially on battery terminals. Your heat gun may allow you to do this without new tooling, depending on how toasty it gets.



Cheers Mark! Exactly the answers I was looking for. It sounds like I might need to buy or borrow a hydraulic crimper for the lugs on the battery wires. I'll try and get something for the smaller stuff and I guess Amazon might be a good place to start looking, as much as I'd rather avoid it.

As for soldering the crimped terminal, that's a great shout and not something I would have thought of. It's a pretty entry-level heat gun but I think I can borrow a big soldering iron or a blow torch from a friend.

Thanks
4 months ago