Low-Input Seed Starting

Gleanings Farm Pix April 2010 030.JPG

The first thing you need to remember is to think ahead, and bring in the compost before three feet of snow and ice lands on top of it. That was my big discovery two years ago, and like so many big discoveries was a. unpleasant and b. completely obvious - in retrospect. Living in a linear society, it can be difficult to get cyclical.

You see, I knew you could start seeds in lightly sifted compost - in fact, I'd seen Rodale Institute tests that showed that some varieties seeds did best in finished compost. So, the year before, I'd gone out in February, dug up some compost, let it defrost, and then sifted it through an old screen and used it, with lovely results. All those living organic bacteria made a very happy arrangement, and the seeds I started that way did far better than those I did in organic potting mix.

Because that winter was an extremely mild one, it didn't occur to me that normally, getting compost out of the pile in February in upstate NY was going to be trouble. If I'd thought about it for 2 seconds, I would have realized I had to do it in October, but I didn't, and thus, the trouble. Every year since, I've taken 10 minutes to shovel and not regretted it!

Which is all just a reminder of how seed starting, as most of us do it, is a heavily energy intensive process. It can involve lights, heating mats, plastic containers, lots of purchased seed starting mixes and various liquid substances that make your house smell vaguely of rotting fish for a week after you use them. All of these substances have to be transported to you. How do you get along without all those things, either if you have to or if you want to? How do you use less of them, at least?

Well, the first thing you'd do is rethink how much you need to start inside. I do a lot of transplanting, from preference - I enjoy it, and I think it saves me time on weeding later and works better with my mulching techniques. But there's no reason why I have to do so much. There are a few crops that need an advance start, but even a few cherry tomatoes will self seed and make a late crop. Now I want tomatoes earlier than that, and different varieties, but I could make do, and start fewer inside. Some crops I get a head start on, like broccoli, could easily be entirely direct seeded. Many perennial crops can be seeded in the late summer, when it is warm, and held over the winter, then planted out the second year, which takes advantage of natural warmth to help germinate seeds. So if I needed to reduce my inputs, the first place to begin would be with reducing the number of advanced starts and rethinking some timing issues.

The next strategy I'd probably use is starting things a little later - my house is quite cool in February, and since space by the stove is always limited, I'd probably need to cut down on the things that simply don't germinate well without some bottom heat in cold temps - peppers, eggplant and basil being some of the biggies. But a smaller number of these could be germinated by the stove, and waiting until late March would mean later harvests (late August, September), but would require less supplemental heating. In March, the windowsills are warmer, because there's more sun and the outdoor temps are higher - not high, mind you, but higher.

Another alternative would be a hotbed. This is a coldframe with a thick layer ( a foot or so) of uncomposted horse or pig manure, covered with a layer of soil, and a cover on top and insulators on the side. The manure, decomposing, heats the soil and creates a great environmental for little seedlings, using wholly natural processes.

In a perfect world, I'll have a greenhouse, and if you are going to use plastic for anything, 10 mil plastic for season extension is probably a better use of time and resources than a thousand little plastic trays and pots. There are a lot of inexpensive greenhouse models out there that can extend a season a little ways - enough to make it viable for those of us in cold climates to do a lot more with less.

What about those plastic flats? Can I get rid of those? Well, they really aren't hard even for a klutz like me to knock together with scrap wood, and we aren't going to run out of old food cans and yogurt pots for a long, long time - ask your neighbors to save them.. With some holes in the bottom, they make find pots for seed starting. Same with old plastic containers. I don't think we'll see a shortage for some time. Milk carton bottoms work well, so do a host of other creative solutions.

What about seed starting material? Well, you can plant things in straight, *finished* (that is, no longer heating up) compost, but that does use your compost apace, and you do have to plan ahead in cold places. Now the next part is controversial. If you use soil, the conventional wisdom is that you are supposed to sterilize it by baking the soil at 250 degrees. That's supposed to spare you damping off disease. My own feeling is that this is stinky, unpleasant, a waste of energy and kinda nuts. That is, I think killing all the good soil bacteria so that you can get rid of a single bad bacteria is a bad idea.

If you use light dirt (you can mix some sand or compost in to lighten it up - I find 1-1 compost and dirt to be nice, I don't bake it, I dig it in the fall (remember, cold weather people have to plan ahead), and bring it in. I mix in the compost, and let it sit. I've never had any more problems with damping off disease using real dirt than I have with potting mix - damping off tends to be a problem when I overwater, not linked to the soil I use.

Two other great options - a soil block maker and a newspaper pot maker. The former uses a compost-sand-dirt mix to start seeds without any framing, the latter uses old newspapers to make biodegradable pots to transplant directly into soil.

What about light? Well, windowsills are still a good idea, particularly if you make a reflector from tinfoil and cardboard and put it behind the plants to maximize light access. But if you haven't sunny windows, you'll have to use hotbeds and cold frames - that is, plants will have to go straight from germination outside, in a protected way. An easy cold frame is an old window and some hay bales, but you can get more complicated and build some structures. I've also seen (but not tried) pop up greenhouses, that can be set over a row in the garden. The big problem with starting out in the cold isn't the cold, but the heat, I find - a bright sunny day can fry your seedlings even when it is quite cold. So either keep a close eye on the temps and open them up a little, or acquire an automatic opener - these are powered by temperature changes and don't need any energy, but they are pricey.

How about fertilizing? Compost and manure teas will do it - they do get a little ripe smelling in the house, but no worse than fish emulsion or most kelp-fish mixes. And if you use compost as a large portion of your seed medium, you won't need much fertilizer, another plus. Or use diluted urine - dilute your own pee 1 part urine to 7 parts water, and use that to fertilize. It is a great natural fertilizer, and very low risk - just stop using it a week before harvest.

Thomas Jefferson reportedly planted juniper seeds in a bed by feeding the seeds to his chickens and confining them where he wanted the seeds to grow. Despite the cold, they did rather well, encased in chicken manure. So there's always that, too - mimicking nature works rather well.

Seed starting doesn't have to be expensive and use a lot of plastic and purchased inputs - it can be simple, cheap, recycled and environmentally friendly, just like the rest of your garden.


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Yesterday, I spent a long time filling seed flats and pressing seeds into dirt - and then I took them outside and set them to germinate. The temps were hovering right around freezing, and there was light snow coming down - the perfect conditions for growing things. Or at least, for winter sowing…

LOL Sharon! Having just yesterday written a loong screed on how I currently do seed starting, this was a whack on the side of the head! Duh... thanks... I think...

I'm raising 300 starts for a fund-raiser and I love my paper pots. You can make them using a small tomato paste can for a form and then twisting the bottoms and stapling the top flap.

By Betsy Robertson (not verified) on 09 Feb 2011 #permalink

That little thing you mention about bringing in compost (and soil too) before it freezes ... I found out the same thing, the same way, some years back. Haven't made that mistake since. It's so much more fun to make new mistakes. ;-)

Similarly to you, I am also limiting what I start early to those crops that seem to do best that way. In my case, lower Midwest springs are short and summer kicks in early, so I prefer to plant cabbage, lettuce, bok choy, kale, and other large leafy crops as transplants so they spend more time growing to size in the temps they prefer. However, as fall crops lettuce and kale do better direct-seeded no earlier than late August. Only bok choy does well as a transplant in the fall, in my experience. Our summer heat is too long and brutal to start and keep transplants of cool-weather crops going, except for bok choy. I haven't had success with fall cabbage yet but will try again with an early cabbage, direct-seeded, this year.

I transplant seedlings of peppers, eggplants, tomatoes, and basil so they can produce food in July, after the leafy crops are done but before direct-seeded summer crops of beans kick in. They take the place of the leafy crops in our diet.

I've found that the 6-packs of cells can last several years if I am careful with getting transplants out of them so I don't split them, or split them more than they already are. A fellow gardener trash-picks these and gives me some. Even those with splits can often be re-used a few times before they really fall apart. I have bought six sheets of 6-packs for future use, but I'm holding on to them and won't use them till I don't have enough of the trash-picked ones any more. (I'll generally start the seeds in wood flats but prick-out the seedlings to 6-packs or 2 inch by 2 inch pots once they get big enough to tangle together in the flat.)

This year I'm going to try to use the heat mat less to reduce electrical consumption. We had our south-facing front porch glassed in last year. I think that by March it will be warm enough to start tomatoes, peppers, and eggplants on the porch with no or minimal use of the heat mat, and no need for lights. I start all the cool-weather crops in a cold frame with re-used windows. Since I'm home most of the time, I don't find it hard to vent the frame, which I do by sliding the windows up or down. The seedlings grow so much better in a cold frame versus in the basement under lights that it's worth it to closely monitor the frame for the right temperature.

I know that less imput is better but if you must use electric lights I recommend buying T5 flourescent tubes which give you considerably more lumens for the same wattage as the old 1 inch diameter tubes. 5000 vs. 2900 and 1/5th the mercury, for 54w each

If you put your plants trays in a main/living room the ambient lights from 2 T5 tubes means you don't need to turn on other lamps from dark until bed, and just have 1 one during the day to suplement the natural light.

In my case we have smart meters and I find it cheaper to run lights from 7pm, at night until morning but I still plan on building a hot frame or small green house for the era when power may not be available.

i've always used the plastic egg cartons (ask friends and family to save them) for winter seed starting. i find that the paper pots (and cardboard egg cartons and anything else absorptive) lose too much water and also seem to lower the soil temperature; i use those for seed starting later in the year on the porch, where its warm and there is rainwater, but not for winter.
last year i finally had real, live, leaf mould, from 6 years of raking and piling leaves. it is the absolute best thing for seed starting ever. thank goodness i already had some sifted in a bucket, because it is all frozen this year. what a winter.
thanks for another wonderful post, and happy almost-spring everyone!

Thanks so much for this, Sharon. I appreciated the more detailed description of what goes into your seed-raising mix. Luckily, we don't have to worry about compost freezing here, but I haven't yet generated enough for much seed raising mix, so have been using a mixture of bought pottig mix (made from rotted pine bark here), light sandy soil and river sand, sieved to get rid of the lumps and choking fines.

I have discovered that toilet rolls, despite their appealing shape make poor seedling containers. My theory is that they absorb both water and nutrients from the soil mix. But generally, I have problems with my seedlings growing leggy and not thriving, even with plenty of light. I probably should fertilize them more, but I often end up chucking them, and buying healthy looking seedlings from the local hardware shop.

I do prefer putting in seedlings to direct seeding where I can, because it makes early weeding easier.

By southernrata (not verified) on 09 Feb 2011 #permalink

*looks out at compost pile buried in snow*

Now you tell me...

All good information and methods for most purposes, IMO. However, for my money, in the case of tomato plants, which are especially susceptible to a number of diseases (early blight, late blight, Verticillium wilt, Septoria, etc.), using a starting mix containing garden soil or dirt (or even possibly compost if it hasn't naturally reached critical heat levels) is risking an early infection in your tomato seedlings. Also, it is recommended that recycled pots/six-packs should be sterilized with a weak bleach solution before re-using for tomato growing.

Mark N., up to this point at least I haven't had any more difficulties with tomato seedlings grown in a compost:garden soil:earthworm casting mix than with any other seedlings grown in such a mix. I've grown seedlings this way for close to 15 years. I don't know if that would be true for everyone; it may depend on fine details of my soil and methods. We haven't had any outbreaks of early blight in St. Louis, so that may help matters for me. But if nothing else, people could at least try homemade mix versus purchased mix and see if it works for them. Like Sharon, I find that for me the more critical issue is not overwatering the seedlings.

Also, I agree that the usual recommendation is to sterilize re-used pots and six-packs with a weak bleach solution. I've never done this in my 15 plus years of gardening. Once my seedlings get big enough to prick out into a six-pack, they seem to be strong enough to withstand potential infection. It might be different if someone were starting seeds in the six-pack, but I start them in flats.

As a chemist, I actually seem to be less prone to using bleach than most people. Bleach-making is a very energy intensive process, plus producing and transporting the chlorine that goes into bleach synthesis is quite hazardous. It's not that we don't use any bleach, we just try to minimize it and avoid its use when not necessary. So far, it hasn't been necessary for sterilizing pots.

Claire, you are obviously doing well with your methods, so perhaps my tomato plant advice is overkill for you. There is more than one way to sterilize pots, too. Hope you continue to have good success.

My experience matches Claire's - I actually did sterilize my containers at first, and ran a couple of years of comparative trials and haven't found any losses, so I gave it up. I certainly would do so if I had disease issues, but I don't think it is worth doing in anticipation of potential disease issues that won't last. Late blight is the only tomato disease that I worry about, and since that persists only in plant material, not on containers, that's not a major concern for me, but different gardeners in different environments have different issues.


Ooh that's a great tip Betsy Robertson, thanks. I had got round to admiring my friends' pot-maker but not yet found a way to make my own and I hope to start a lot in pots this year. (I want to try growing a little amaranth and quinoa here at ~52.4 N.)

Thanks for this very timely post Sharon Astyk!

The university botanical garden I worked with as part of my undergrad honours project used 1:1:1 humus (organic-matter rich dirt): coir : sand for seed compost.

The coir is coconut fibre waste & is imported (in the UK) but I have been wondering what else would have a similar effect - broken straw? shredded matured tree bark? (fresh Shredded bark would be phytotoxic like unfinished compost).

@Alice Y. Thanks for the thanks. Also, I've found that if you wrap a couple layers of duct tape around the can it evens out the ridge at the top of the can making it easier to remove the pot.

By Betsy Robertson (not verified) on 11 Feb 2011 #permalink