The Basics of Starting Seeds

In keeping with the reminder I got that I should back up a little bit, and present my ideas more coherently for those who haven't encountered them before, I thought I would add a post about why someone might want to start seeds, and how to do it, to supplement the posts on winter sowing and the sowing of perennials from seeds.

New gardeners generally start out by buying their seedling, and depending on where you are getting them, this can be a problem. The destructive wave of Late Blight that hit the tomato crop across the eastern half of the US was derived from seedlings purchased at big-box garden centers. Because the spores are windborne, it spread all over the country, killing tomatoes indiscriminately among those who grew their own and those who purchased. Moreover, if you are concerned about chemical use in agriculture, many of the seedlings you will buy at garden centers will be heavily sprayed.

That's not to say that people shouldn't buy plants and seedlings - I'd be a bit of a hypocrite to say so, since I sell plants and seedlings. If you are starting up with gardening and don't want to begin with seeds for plants that need an early start or don't have time or space to start seeds, buying from someone who grows them locally is a good idea. But a packet of 20 tomato seeds from, say, Pinetree Gardens can cost under $2, whereas you'll generally pay 4-6 for just six plants. Moreover, you are limited by what's available - my local garden center offers 3 kinds of hot peppers - my own seed collection includes 30.

The first things people are likely to start from seed are common annual heat-loving vegetables. In most climates in the US, either because it is too cold early, or because it is too hot at summer's peak, it is necessary to start tomatoes, peppers and eggplants from seed indoors to get a reliable crop. And in some places, you'll want your tomatoes earlier, even if they could germinate from direct sowing. In my climate, I can get only small varieties of tomato to mature from direct sowing, and peppers and eggplant never get there at all. Many other vegetables do better if they are started indoors and transplanted, rather than direct seeded, and some cool season vegetables will produce a lot earlier if started from seed - broccoli, cabbage and brussels sprouts are generally started from seed as well.

Those are the most commonly started seeds, but there are literally hundreds of other things you could start from seed - many herbs (especially basil) and flowers, as well as the perennial I mentioned in the two other posts. If you are a beginner, though, I would keep it simple. You can get very complex with timing and succession sowing, but let's focus on the basics.

The most common garden vegetables started early from seed indoors are:

Tomatoes, Peppers, Eggplant, Basil, Parsley, Onions, Broccoli, Cabbage, Brussels Sprouts.

Plants usually sown directly into the garden:

Peas, beans, beets, carrots, dill, cilantro, melons, squash, cucumbers, spinach, parsnips, asian greens, mustard

Some plants, like lettuce can either be given a head start or planted out directly. A few, like melons and okra can be started indoors to give them a head start in cold climates, but should be planted into newspaper pots or other decomposable mediums, because they don't like having their roots disturbed and suffer from transplant shock if you try and put them in a regular flat.

To start plants indoors, you need containers - these can be recycled from egg cartons, yogurt containers, etc... or you can acquire flats specifically for this purpose. I like plastic egg cartons, personally. Make sure, however, that you cut drainage holes in any container.

You can purchase a seed starting medium at a garden center, or you can start seeds in sifted compost if you've got it. Garden soil itself isn't a great medium - it is too heavy. But light soil mixed 1-1 with compost will do. The conventional advice is that if you use soil or compost, you should bake it at 250 degrees to kill bacteria that might infect your plants. My own observation is twofold. First of all, baking compost or soil stinks to high heaven. The second is that it doesn't seem to be necessary, at least for me - several studies have suggested plants actually germinate and grow better in compost, and I've had less damping off in 1-1 compost and soil mixes than with purchased potting mixes, but YMMV.

Fill your containers with soil, and insert seeds. In general, good seed companies will include instructions on the package, but you might also want a reference book for the specific conditions that will ensure best germination. I like Nancy Bubel's _The New Seed Starter's Handbook_ and Suzanne Ashworth's marvellous _Seed to Seed_. These are useful for reminding us when, say, a seed needs some light to germinate, or what temperatures it germinates best at.

If you keep a cool house, finding a way to germinate heat lovers like peppers and eggplant is challenging - with temps in the 50s and low 60s, they can take more than a month to germinate. Some people use heat mats that provide consistent bottom heat, but these are expensive and energy intensive - I also know people who use the top of their fridge, the top of the dryer, back of the woodstove. Cool season plants like broccoli and cabbage don't need the warmest spots, so put them over by the window.

Keep the soil evenly moist and the environment as humid as possible - purchased flats usually come with a plastic dome, or you can put the plants in a plastic bag until germination, or just leave them in an area where you also keep a bowl of water to evaporate. Don't forget to check them regularly though, or your seedlings may end up leggy and stretched out as they reach desperately for light.

Once they do, a sunny windowsill will do great for your seedlings - if the light isn't good, it can help to put old foil on a piece of cardboard or a mirror behind your seedlings for reflective purposes. Keep them evenly moist, but not too wet - a little fuzzy-white mold doesn't matter much, but probably indicates too much moisture. Water from the bottom, not the top, or with a mister to avoid disturbing seedlings. Other people use flourescent lights - if you do this, you'll want one warm and one cool light spectrum bulb.

After the first week or so, you can fertilize lightly with kelp or fish fertilizer or compost tea. Nearly everything you can use that isn't Miracle-gro stinks a little - and Miracle-Gro stinks, but in another sense. Honestly, the least stinky and best option I've found is diluted human urine - dilute 1-10 and use to water seedlings. At that dilution, it doesn't smell, provides a balanced fertilizer and doesn't help deplete the oceans. I know that instinctively sounds weird to people, but urine is an excellent fertilizer, and unlike human feces, is not a major disease vector, unless you have tularemia, in which case you've got bigger problems than what to feed your seedlings. If you stop fertilizing with urine for two weeks before you harvest any plants, there's not even the most distant gross-out factor. But if you prefer pureed Menhaden, you can get that too - even though that seems more troubling than pee to me.

The major problem people have with seedlings comes from damping off disease, which is caused by lack of good air circulation and too much moisture. It is a fungus, and it is pretty easy to control - open a window now and again, or run a fan, and don't overwater. You can also water occasionally with dilute chamomile tea. But if you keep the soil from being soggy, you shouldn't have a major problem.

Keep your seedlings happy with food, water and sun, and then when you are ready to plant out, comes one of the most critical and neglected pieces - hardening off. If you take your plants out of your sunny window and bring them out on the first warm, sunny day and stick them in the ground, I promise I can tell you what will happen. A large portion of them will turn whitish, and drop dead. This is because of transplant shock, caused by going from an incredibly protected environment to a very unprotected one. So you need to harden off your seedlings.

What does that mean? Well, it means they should go outside gradually. Put them out one afternoon, late in the day, on an overcast, not too windy day. Leave them out for only a couple of hours, and then bring them back in. The next day leave them out a little longer, and give them some direct sun - but only a little. At the first sign of whitening of the leaves, bring them back in. After a week of gradual transitioning, they can live outside.

When to plant out depends on the plant - cold lovers like broccoli and cabbage can go out as soon as the weather is settled into spring and it is dry enough to plant. Tomatoes should wait until after your last frost date. Real heat lovers, like peppers, should probably go in a week or two later, when the nights are consistently warm.

That's about all there is to it - honestly, I can't imagine life without seeds to start - what would I do in February if I couldn't get arm-deep in the compost?


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This was a very useful and informative post. I've had seeds started for my brassicas for a while, and have wondered about that fuzzy white mold, and why they look so leggy! ha.

and congrats about your book going into a second printing. i just bought it a couple of weeks ago, and am planning to dive into it this weekend.

I usually start squash & cukes indoors, too. Our mean growing season is 163 days but the variance is high. This coming weekend we're starting our tomatos & chilis.

By darwinsdog (not verified) on 18 Feb 2010 #permalink

I started my cukes and some carrots inside this year since the cukes transplanted really well last year. I'm starting more seeds tomorrow, my kids and I love it! The next 5 day temps are showing a turn towards Spring!!!

If you include earthworm castings in your seed-starting mix, you won't need to fertilize. This is what I do, and I get high compliments on the health of my seedlings. I use a mix of 4 parts compost, 4 parts garden soil (mine is a silt loam), and 1 part earthworm castings from my worm bin. I never add any other fertilizer to any of my seedlings.

Years ago I read in Organic Gardening that a thin layer of compost on top of seed-starting flats will help protect against damping-off. I do this and have almost no damping-off. Plant the seeds into this layer.

Last year I found what seems to be a pretty good way to use the heat mat: I wait till the end of February (about 6-8 weeks before my last frost) to start any seeds needing use of bottom heat from the mat. As soon as the seedlings are up, I put the flat into a cold frame (a bottomless box with a clear top that in my case sits on an asphalt pad) - by that time it's about mid-March and the cold frame is a hospitable environment. Then I can turn the heat mat off. The seedlings need a good deal less heat to grow than the seeds did to germinate; the cold frame is sufficiently warm most days. If it's going to drop below freezing (at night or on a cloudy day), I bring the frost-sensitive seedlings back into the basement under lights. This minimizes use of heat and light and gives me better-quality seedlings that are already hardened off.

Sharon, what seeds do you have started? I (NE Pa) have only onions so far.
All the best & winter well!

I've had good luck starting seeds in stump dirt. I have a few old, hollow trees in my woods, and each year enough of the insides decay down that I can gather a five gallon bucket or two. It's soft and fluffy and absolutely perfect (and free!)

I live considerably further south than you (in Virginia), but I've found that most things that people start indoors will do just as well when started in a cold frame. I've even gotten to the point where I start tomatoes in a cold frame rather than indoors --- the ones started indoors are much bigger at the time I'd set them out, but the transplant shock slows them down so that the cold frame ones catch up and do the same. So much less work too!

You forgot one really important thing. We haven't grown veggies (no space) but we love morning glories and have tried year after year with mixed success. They have very hard seed coats and take forever to germinate. In our very first year, we learned a really important lesson. When the weather warms up and you start to take the little darlings out to sit in the sun, you MUST cover the seedlings with a screen or else you will just feed the birds.

Here in western Oregon, even though we have a pretty mild climate, I have begun planting more things as starts rather than direct sowing. We have little critters here called Symphylans that can gobble little seedlings, and its damp so damping off of direct seeded plants can be a problem. This year I'm going to try spinach and beets as starts - plants I always used to direct sow. For Oregon gardeners, I have a few seeding resources - a local seeding calendar and a couple of good local seed companies listed here:

Tomatoes, peppers, and eggplantsâdeadly nightshades, ick.

Damping off has always been a problem for me. Thanx for the suggestions, I'll give it a go again. I'm going to try mixing some worm casings in, as I've got two nice worm bins going.

I'd love to see a post on how you organize and store your seeds, and how much you have in storage! My seeds are catalogued now, and I can't determine the effect of freezing and unfreezing the seeds to store them. I could just put everything I don't use in one bin, but then I'd have to pull the whole thing out each year... Or I could store what I estimate is a year's set of seeds? I wish this knowledge wasn't lost to so many of us that we have to try and reinvent the wheel all the time!!!

By Christina (not verified) on 20 Feb 2010 #permalink