I grow flowers from seed in my greenhouse for three reasons.
- I feel a strong urge to grow things in late winter when it is fairly impossible to grow anything of significance outside.
- I will succumb to fewer impulses buys of flats of flowers if I know I have my own to take care of at home.
- I can often keep better track of my flowers if I plant seedlings into the garden beds, instead of just seeds.
Cosmos are a particularly gratifying flower to grow from seed because they sprout easily and quickly, the seedlings are not touchy, they get relatively large and vigorous within a matter of days, and they are not picky about transplanting. Not only that, but they do well in my southern Idaho garden, flowering all summer. Their deceptively wispy looking foliage handles the summer heat well, and, if they are in a place that will get enough water in the spring, they will likely reseed.
I put my cosmos seeds in pots on March 23 this year. To begin with, I used Happy Frog potting soil that I bought at D&B Supply, got it the regular morning-oatmeal-moist, then filled 3 inch pots. The cosmos seed are long and skinny, so all I do is poke them straight down into the soil, like I figure they do to themselves outside. Then, I moisten the soil with a misting spray one more time, to make it all settle into contact nicely with the seed. (click on any photo to enlarge)
This year, I covered my seeds (waiting to sprout in soil in pots in trays) with plastic wrap. I have often done it with 10 gallon clear waste basket liners, but I ran out of those last year and plastic wrap was available. The advantages to the plastic wrap are that I can see sprouts right away, it lays flat on top of the tray so the trays fits under the greenhouse lights (which I was using for warming this year, along with a space heater), and it can be cut exactly to size for the tray (I cut it long enough to make contact under the bottom of the trap, so that it will stay put). The disadvantages are that if you don’t see the sprouts right away, they have no place to grow and can get too moist and stuck to the layer of plastic; and it is harder to take off and on should you need to add moisture before the seeds sprout.
When my cosmos seedlings were about one inch tall, I decided, once again, that I couldn’t just thin out all the extra ones in each pot. The soil was almost all the way dry, but the plants were not at all droopy, so I went ahead with dividing them before watering. Most of the pots had 2 -3 sprouts. I chose the 2 that were the most well spaced and the largest, then thinned out the others.
Next, I carefully placed my fingers over the top of the soil, my fingers spaced around the stems to avoid harming the remaining seedlings. This made it so I could turn the pot upside down and let the fairly firm contents slip out of the pot to sit in my hand. Most of the time, the soil all stayed together, but if it didn’t, it was just a minor inconvenience.
The main thing is to NEVER hold the seedling by the stem. When the seedlings are this large, I usually begin trying to see if the soil will break into a clump such that I can just pick up the whole little root ball. Sometimes, I go ahead and hold the seedling by a leaf to help support it. If the soil falls away, it is easy enough to dangle the root into the pot where it will continue to grow.
Most of my cosmos soil clumps divided in two so that I was able to set them inside the same kind of pot (I did reuse the original ones right away, too). Then, it was just a matter of filling the other half of the pot with moistened potting soil, slightly tamping it down, and watering a bit again.
Two weeks later, they are all 2 – 3 inches tall. None of them even looked stressed out about being transplanted. I have been hardening them off, too, and now they are up to spending about 5 hours out in the April sunshine every afternoon. I may still plant some cosmos seeds directly into the garden, because there is always one more thing I want to plant. None of the seedlings have flowered yet (when do those commercial nurseries start their seeds that they are flowering when I see them in early April at the stores!?), so if you want to see what the variety I am growing looks like, you will have to go to the website of the company that I bought the seed from: Antiquity Cosmos
If you want to read about other fun flowers I have started from seed, just type “fun flowers” in the search bar, or click on this link: