Johnny's Selected Seeds has a nice overview article about the pros and cons of several different seed-starting methods. This post is mainly a review of that article.

I started the thread to invite people to share their favorite indoor seed-starting methods, resources, tips and gotchas. (*)



http://www.johnnyseeds.com/t-s...

- "traditional" 1020 trays and plug flats
- 20-row seed flats then potting up quickly
- biodegradable pots like "Cowpots"
- soil blocks - air pruning of roots! (with video)

(Johnny didn't mention starting seeds on paper towels or coffee filters, in plastic bags or other humidity enclosures, as suggested by Dr. Deno. Then pot them up one or more times before transplanting outdoors. I use coffee filters cut to fit the bottoms of stacking, nestable glass bowls. I use up a lot of space, but it let's me inspect them all very easily.)

Johnny didn't even mention what I think of as the "traditional" way to start seeds indoors, namely broadcasting seed thinly over a seed flat, then "pricking out" the seedlings and potting them up as soon as any true leaves appear. Or at least before the roots get too tangled.

I started to like this seed-flat method when I realized that I could use the big inserts from an 1801 tray (18 cells, 3"x3") or 2401 tray (24 cells, 2"x3") as mini-seed-flats to start 18 or 24 different varieties in one 1020 tray. Then, DUHH, it sank in that I could use a simple 4" square pot as a seed flat if I filled it shallowly.

I still get queasy when I untangle tiny naked baby roots, but they seem able to survive it.

I liked their suggestion for starting lettuce in 200-cell flats, but they start 2-4 seeds in each cell! Then they cut all but one.

They start tomatoes and peppers in 20-row flats, then pot up to rigid 50-cell square plug trays. I would have thought those were pretty small for tomato seedlings! Maybe I keep them in pots too long, but I've carried trays of tomato seedlings back indoors at night, for as many as tyhree weeks.

Johnny's uses a bleach substitute for sanitizing plastic trays ("Oxidate", with Hydrogen Peroxide and Peroxyacetic Acid) . I guess I should consider using peroxide instead of chlorine bleach. Actually, after I clean trays outdoors with a sprayer and scrubbing, I often run them through part of a dishwasher cycle.

(*)

I think of there being four main ways of starting seeds:

1. Direct sow in the final spot outdoors (maybe with floating row cover or polyfilm)
2. Sow outdoors in a cold frame / seed bed, then transplant
3. Sow outdoors in a jug, then transplant (winter-sowing)
- - 3.a - - classic potting-soil-WS with drain holes and vent holes to let air and a little rain in
- - 3.b - - Jonna-style WS with sealed containers and coarse vermiculite.
4. start indoors, (maybe pot up), then harden off then plant out

Another is Johnna's method of starting seeds in vermiculite. I had good results with that on echinacea last year, but failed miserably with begonias. They sprouted buy stayed so tiny for so long that they just sort of fizzled out and croaked.

Karen

Good point, Karen. Her website has to be rebuilt, so I can't link to it.

As I recall, she had a variation on winter-sowing where she used very coarse vermiculite (nothing else mixed with it), dampened it, sowed seeds, and then sealed it tight with no air holes or drain holes.

I forget whether she kept the WS containers indoors, outdoors under cover, or outdoors and exposed.

My last two photos are just a thin layer of medium vermiculite over a random bark-peat mix. It as the first time i winter-sowed and was really just learning. The only ones that worked were penstemon, that sprouted and grew so slowly that I almost threw them away, thinking they were algae growing on the vermiculite or Perlite.

Then I had a similar problem to yours. The Penstemon grew so slowly that they were still around 1/2 inch tall many months later, and they dried out in a temporary cold frame. I don't think that was any effect of the vermiculite layer, just Penstemon growing slowly as they tend to do.

But that reminds me of another popular seed-starting method: Deno's paper-towel-and-baggie method. I'll go bk and add that.

@Jonna, are we describing your technique correctly?

Yes, I was going to link to Jonna's website too, found it to be down.

Your description of her technique is right- dampened vermiculite in a plastic tupperware-type container with a snap-on lid, no holes top or bottom. The lid stays on the whole time. She uses this technique both indoors and for wintersowing I believe.

Karen

The paper towel method is really useful for seeds of questionable viability. And I always start my morning glory seeds that way. For some reason I get much better germination rates than putting them directly into pots.

I think that Jonna said she found coarse vermiculite in a builders' supply store. They sometimes use it for insulation.

I buy my vermiculite at a hydroponics store.

Karen