Seedling Update

Earlier this month I had my first seedling sprouting in a seed tray. Several people joined me in celebration (thanks, guys!) Today things are a lot busier. I have four flats that are full to mostly full. Each flat holds 72 seedling compartments and currently I have 0 to 3 seedlings in each little cup. I try to plant 2 seeds per cup in case one doesn't germinate but sometimes none sprout and sometimes I accidentally drop more seeds. And I have a few plants like thyme, oregano, and chamomile that have such tiny seeds I just sprinkled them lightly and now there are tons of little seedlings in those cups (see above, full-sized). Thinning is going to be a challenge.

Because I'd never started seedlings before, I wanted to try some different things and see what works best for me. I began by starting my seeds in three different environments:

1. Tray on heating pad, no dome
2. Tray on refrigerator, no dome
3. Tray with dome, no heat source

I quickly learned that for me option 2 was a no-go. Even though germinating seeds, by and large, don't need light, I found it too tedious to check the top-of-the-fridge tray on a timely basis. In other words, I forgot. The first seeds sprouted and get long and leggy in no time. Keeping the tray under lights works better for me.

I didn't observe any difference in sprouting time for the trays on the heating pad (no dome) and the trays under a dome (no heat source). I've decided I prefer the domed trays for starting seeds, for a couple of reasons.

1. More consistent water level
2. More free outlets

The dome creates a little miniature rain forest and the soilless starting mixture stays uniformly moist without drying out or getting soggy. This isn't the best photo - I was using a camera without manual focus and couldn't trick it into focusing on the seedlings instead of the water droplets on the dome, but it shows how nice the moisture is in the domed tray.
I need all the outlet spaces I can get for my fluorescent lights. I don't want to "waste" an outlet for a heating pad.

I arranged things thusly: I have two flats set end to end long ways, with two 48" flourescent light fixtures side by side above the pair of flats. Each fixture holds two bulbs, so there are four bulbs illuminating two trays. This seems to provide plenty of light across the surface of the flats and the seedlings don't lean much. I use regular 40 watt bulbs. I didn't worry about special spectrum grow lights because my reading indicates they don't make enough difference to justify the cost. Maybe next year I'll run my own tests on this and come to my own conclusions.

Once the seedlings are well sprouted, I move them to an undomed tray as shown in the first photograph. I do this for a couple of reasons.

1. Lower temperatures
2. Damping off disease

Most seeds germinate around 70-75F but the seedlings like slightly cooler temperatures for growing. This varies from species to species but overall this is the case, so I take sprouted seeds out from under the dome to give seedlings a slightly cooler growing environment.

Damping off disease is caused by a fungus in the soil and it likes a cool moist environment. I use a soilless seed starting mixture. I bought mine but you can make your own - I think you use Peat, Vermiculite, and something else, but Google it. I'm still paranoid, even with the soilless starting mix. My reading indicates that if I allow the "soil" to dry out (even to the point that the seedlings begin to wilt just a little) then the dryness will help deter damping off disease. I don't let my seedlings wilt; I think that will set back their development. I do let the top of the starting mix begin to dry out and then water from the bottom by putting water in the tray beneath the cups.

Once the seeds have sprouted I use half strength Miracle Gro when watering them. I'd like to try fish emulsion but Miracle Gro was readily available.