What vegetable seeds can I NOT start off in a seed tray/plugs?

Evening all,

Got lots of different veg seeds today and I read on the packet that the lettuce seeds must be sown outdoors (which I assume means direct sowing). I remember though buying little lettuce plants in plugs so I was wondering..

what vegetable seeds can I not start off in the polytunnel (in trays, plugs etc) to transplant later?

Or more specifically can I start off carrots, beetroot, radish in seed trays/plugs?

Thanks

Samuel

Sweetcorn does not like root disturbance, or anything which wants to put down a long tap root like carrots etc. You can get round this a bit by using extra long pots or tubes. Some plants don't like a check to their growth, so if you started them in the polytunnel then moved them outside, even if you didn't disturb their roots, they would sulk because they felt cold. Hence the need for careful "hardening off".

Others will have more examples, I don't know much!

Actually, corn can be transplanted, the North Koreans do that as a general practice to get a start on the growing season. And carrots too, but you have to gently tease them out of the starter pot with a toothpick and get it transplanted when it is only about an inch tall, while the root is still fairly short.

The general rule is that root crops are best started out in the field and not transplanted, but beets (beetroot to you UKers) are another exception to that rule, as long as they are still small. Beans are another general category that is best sown in the field.

I find that the larger the starter pot, the easier it is to have success with transplants. Rather than start a dozen plants in an egg carton, each one to its own well, start them together in a 6" diameter pot, where they may have 4"-8" of soil to put roots down into. In my experience, there is more stress on the seedling to be in some cramped thimble for the first couple of weeks than to be separated later from its siblings and set out into the garden.

I would like to also throw out the question about the soil blocks (pot-less) methods and if things that are normally tempermental to transplant can be sucessfully transplanted when propigated in soil blocks instead of actual pots?

Beans
I'm not transplanting 5000 beans. This is a job for the Earthway Seeder.

Peas
Quick to germinate, sends out a long root in just a couple of days. The value per plant is low, may not be worth your time to transplant. I've got 2 cultivars I'll be growing this year. The one I want was only available in limited quantity. I'll be treating these like gold and starting them in tall pots (20 oz Solo cups). For the bulk seeds, I've used the Earthway to great success. I've also tossed the seed as grain and walked away. When they sprout I go back through and plant branches or bamboo for them to climb.

Squash
Most are quick to germinate and grow to considerable size rapidly. The large leaves can be cut on the inside edge of the pipe (see below). Your call.

Corn
As with peas, the roots outgrow the pot in just a few days. With a pot several inches tall, it can be done.

Tomato
I find starting them in small pots is the way to go, but the roots have to keep growing. I follow the rule: stunt the roots, stunt the plants. Pot up a couple times if need be, or start them in at least a 20 oz container.

Carrots
I see carrots as a low value crop not worth the labor cost to transplant. I'll be trying out soil blocks for the first time. In blocks, transplanting might work well: the spacing is so close I can set the blocks in contact with each other right on top of the bed.

Radish
I grow them now and then but I don't eat more than a handful. If I have a space to fill, I might poke in a few seeds.

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Starting in Cells
I've used 1020 trays with 72 cells. Handy things to start a pile of seeds in a small space. Most plants will grow roots out the drain hole within a week of sprouting. Transplanting when the plants fill the depth of the sell means a small plant. Potting them up takes time, but it's a good job for rainy days and evenings. I find these cells to be terribly fragile and went looking for alternatives...

PVC Pipe
Controversial due to claims of outgassing. Most pots are smaller at the bottom than they are at the top, but roots want to grow wide as well as deep. The pipe is straight, giving the roots a little extra room. The smooth interior makes transplanting a breeze: dig a hole, set in the pipe, back fill, tap the side, lift. Larger leaves need to be protected from being cut on the inside edge. These last a long time-I have some I cut 10 years ago that are holding up just fine. I've tried 1" pipe as a replacement for the 1020/72 cells, cut to 2" long, but still encounter the fast growing root obstacle. An advantage is the ability to select the length of the pipe. I've used 6" tall sections of 3" PVC with excellent results. Another advantage is being able to tilt the pipe to see if the roots are reaching the bottom. Long lasting and durable, but can be expensive and they don't stack.

Plastic Cups
Cheap, more durable than the 1020 cells. I use them for my coffee, keep them for growing transplants. Anything that saves me doing dishes gets my approval. I cut small pieces from the bottom corner for water drainage and absorption. Can be reused several times before cracking/breaking. 15 fit in a 1020 tray, 9/sqft. Can get heavy so I use 2 trays together for added strength. I put them in 5 gallon buckets to move to transplanting. Start the seeds in 72s, repot into the cups. I've sold many transplants in these. If I use a plant label and stick one in a group of cups, the customers take the plant with the label. A sharpie will write on the cups clearly. With constant sunlight, these last maybe a year. A distinct advantage for me is the depth of the roots and size of the leaves. The plants go into the ground with some drought tolerance due to their size-big roots. Also, larger plants will hold up better to cutworms-a menace around here.

Azalea Pots
Commercial plant pots work fine. I want something with more depth and cheaper so I use the cups. For plant sales, this is professional route.

Pricking Out
Start a group of seeds in a single container and prick out the seedlings as they show up. LAWDY this is tedious, I'd rather staple pastrami to my face. I'll use this for tiny seeds such as Oregano. With my eyesight I can't even see the seeds.

Peat Pots
Too expensive for a single use in my view. For selling transplants these can be appealing, but I fin that if they get too wet they can split, sag, and fall apart. Transplanting is dig a hole, set in the pot, backfill, move on to the next one. Nothing to carry back to the greenhouse.

Soil Blocks
Yup, I'll be trying this over the next few weeks, if I get the time. Being I may be too cheap to cough up the money for a soil block maker, I'll probably make one out of that PVC pipe I've got. Lots of sweet talk about them, no plastic pot to throw away.

Glass
No, I would bleed to death.

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Trays

1020
Not particularly expensive. Used to be found for a buck each in places. A case of 100 will run you $70 plus way too much in shipping because of the size. Tend to crack if lifted with too much weight. Double them up for more strength-put the cracked one on the inside. Will last for several years if not cracked. Will not hold up to being stepped on by a bull.

Cafeteria Trays
Carlisle makes a fast food tray, 12" x 16" that is excellent. You've probably usxed something like this at a buffet or fast food joint. 12 of those Solo cups will fit, about 16 pounds dripping wet, not too much weight to break them. Just enough lip to water to last a couple days. They hold up very well to sunlight and are easy to clean. Stackable. Less than 3 bucks each brand new with shipping. Can sometimes be found in used restaurant equipment stores. Also handy under the coffee machine, in the spice cabinet, on top of the dryer, breakfast in bed, feeding someone with the flu, in the workshop, and for hosting a BBQ. These get my vote.

Baking Pans
Coated steel baking pans rust heavily in seconds. Save yourself the trouble and throw your money in the trash can right now. Aluminum sheet pans, 17" x 26" are out there and will hold up without rust. Can be expensive, don't fit standard greenhouse shelves, can be HEAVY when loaded, and can pit after several years. Lots of dialog about aluminum and health issues. Stainless steel is available but is cost prohibitive for a working Joe like me.

Disposable Baking Pans
These will be aluminum (in the UK: Aluminium). Lightweight, can't pick up the whole tray when loaded with plants of any size without bending the tray all to hell. At least you can reshape it. Try putting them on a board.

Wood
I've made em. A shallow box with a plywood bottom. Can be done cheaply with scrap lumber. Put the water to them the plywood blisters, the lumber gets moldy, screws and nails rust. Use them for a while, then put them in the RMH.

Samuel Morton wrote:I read on the packet that the lettuce seeds must be sown outdoors

Round here, it's very common to start lettuce in pots/polytunnels.
Others have covered the main direct-sowing candidates.
While just about anything can be transplanted if you really want to, I always direct-sow legumes, root crops and cucurbits.

John Elliott wrote:

Actually, corn can be transplanted,

Check, this is the only way we get corn in the NW - corn sown to early when its too cold or wet rots in the field. Beware of mice even when starting in the greenhouse though

John Elliott wrote: And carrots too, but you have to gently tease them out of the starter pot with a toothpick and get it transplanted when it is only about an inch tall, while the root is still fairly short.

That sounds like way lots of trouble. I have always sown carrots and radishes into the field. Carrot seeds are tiny.

John Elliott wrote: The general rule is that root crops are best started out in the field and not transplanted, but beets (beetroot to you UKers) are another exception to that rule, as long as they are still small.

I've never seen a reason to transplant beets - I'm sure you can transplant beet or carrots if you need to though

John Elliott wrote: Beans are another general category that is best sown in the field.

I've done both - it depend how many bean you're putting in. Its a big seed.

John Elliott wrote: I find that the larger the starter pot, the easier it is to have success with transplants. Rather than start a dozen plants in an egg carton, each one to its own well, start them together in a 6" diameter pot, where they may have 4"-8" of soil to put roots down into. In my experience, there is more stress on the seedling to be in some cramped thimble for the first couple of weeks than to be separated later from its siblings and set out into the garden.

Now that John mentions it I kinda like the idea of growing into egg cartons. Poke a few holes, transplant when wet... I may toy with that one.

I offer a different perspective on starter pots. I think a larger pot = better roots = less chance of you plant dying - BUT you need to make sure the roots have colonized most of whatever container you are using before you transplant it or your in for a crumbly mess. I have plenty of luck with high success rates out of small plugged trays. It depend on your crop and conditions of course

One thing you can always do is cut the bottom out of your pot (if you're transplanting something large that you don't want to shock) set it on bare ground - wait for a couple weeks then remove the rest of the pot and hill up around it with mulch or compost.

As for lettuce Samuel, I've never met a lettuce that couldn't be started early and then transplanted out. They might be out there - but I've never seen 'um. You can direct so it too if you like of course. I've done that with mix. But I always transplanted head lettuce. Also tricky to transplant are squashes, cucurbits, and peas. Though due to climate I have always started squashes and cucurbits inside. Never peas though.

Jen Shrock wrote:I would like to also throw out the question about the soil blocks (pot-less) methods and if things that are normally tempermental to transplant can be sucessfully transplanted when propigated in soil blocks instead of actual pots?

I've used soil blocks at a couple places. If you can get your soil mix down (not to muddy not to crumbly) and get all your seedlings growing at the same pace (they REALLY need to be totally grown out before transplanting) and get it to work for your scale (I will NEVER use a 4x soil block hand punch at a time again - I'd rather eat fist fulls dirt) Then they work great.

Seriously. If you can make a tray full at a time easily and consistently and which will work for the volume and scale you're going for soil blocks can work just as well as anything else.

Home gardeners are a lucrative side market to the industrial horticultural industry. We are sold the same products at grossly inflated prices.

We fumble around “pricking out” and transplanting our seedlings, imitating machinery in a terribly inefficient manner. at best disturbing however usually damaging their tender tissues above and below the soil. “hold the leaf not the stem”, the industry provides us with informative advice to minimise the unnecessary damage and make their products viable. When transplanting the final time into the garden or greenhouse we are encouraged upon removal of the plastic pot to tease out and break the roots to encourage and allow the roots to regrow in the directions and manner evolution and species survival dictated.  

Transplant shock is real to all plants and deadly to a few. And rarely is the question asked is this the best way.

Plastic pots, modules and trays are developed to interface with automatic pot filling machines, automatic seeders and robotic transplanters for reduce labour on large operations, plastic pots require sterilisation between sowings and cause unnatural tangling of the roots and transplant shock when planting out.

If not added to landfill, stacks of plastic become a perfect habitat for slugs, snails and overwintering pathogens to grow and multiply often leaving the home grower to reach for yet another poison or cure. For those growing without the aid of machines and sterilisation plants, these biodegradable and thin-walled Coco Coir Pots are a far better option.

100% biodegradable and designed to be planted with the plant in a prepared hole in the garden where the roots will grow freely through the wall in the direction nature intended. Seedlings also benefit from the nutrient boost and the addition of organic matter from the decomposing coir pot. No mess, no fuss, less work and most importantly no transplant shock or growth check.

Unlike peat pots, Coco Coir Pots are 100% sustainable. They are not as susceptible to mould and will resist turning into a soggy mess before planting time which are attributes of the paper pulp variety.