Greenhouse time is a fun time. When else on the farm can you stand around in one spot listening to music and chatting with coworkers (or coworker, rather)?
The early weeks in the greenhouse are fairly simple. We generally start most of our cool weather brassicas (kale, collards, broccoli, cauliflower, cabbage, etc.), some head lettuces, and some other cool weather crops. Somewhat intuitively, these crops don’t mind cooler temps in the greenhouse: when it’s 59° F, they germinate in 9 days; when it’s 86° F, it only takes 4. But really, what is an extra 5 days to wait? Is it worth the extra cost of propane to heat that air space? Not in my mind.
So, all is good in the greenhouse until that one day when our winter devised seeding plan kindly tells us to start our peppers. Peppers take longer than anything else in the greenhouse…about 8 weeks. Pepper seeds are easy to sow, but unlike our cool weather crops, they like heat to take root and crack through their shell. Those temps listed above for cabbages…not the same for peppers. At 59° F, they take a whoppin’ 25 days to germinate and at 86° F, only 8 days. If seed rot has ever been a problem before, it’s sure to be a problem while your seeds are waiting in a cold moist environment for 25 days!
I’ve seen and practiced many ways to heat your soil to said temps…I’ve tried the 20-row and open flats, where you seed so closely together that they all fit on a 2×6 heat mat…yep, 1500 pepper plants fitting on a 12 sq. ft. space is crazy. So when they finally do germinate, we take the time to prick each seedling (with hardly a root structure) and place them into a viable container size so they’ll grow until time to be transplanted, taking time and lots of soil and patience.
I’ve seen little racks that have plastic on the sides for a similar high density planting. Usually this too requires transplanting the plants. But, it does bring forth an important principle about light in germination. Things like lettuces and some herbs and flowers need light to germinate. Peppers prefer total darkness and don’t mind being stacked.
Last year we had a problem. Once the delicate seedlings were transplanted from their congested heat mat, we started to see damping off…yep, the dreaded fungus that can take trays and trays of plants. We had to replant them all, leaving us with a very late start on our peppers. This year I said no more to the transplanting of the baby plants.
So, our solution? We built a tower of boards and bricks and trays to house all of our peppers in their individual cells (in 128s). We covered the tower with additional greenhouse plastic to hold in excess heat and humidity and added a small ceramic heater in the bottom. Wondering if this ‘ghetto’ engineering would actually work, we put a thermometer in with the pepper trays. Sure enough! When our heater is set on 55°F, our pepper tower stays at a miraculous 85°F. Even when it’s 28°F outside, it still stays toasty in our pepper tower. As soon as these babies pop, I’ll let you know how long for germination. Last year it was around 18 days…heat mat and all, this year, I’m betting on 10 days, tops.
In other news, all brassicas are up in a healthy flush of green butterfly shaped
cotyledons. And of course we sing to these babies and stroke their delicate first leaves. I’m pretty sure they can feel our joy. Our first brassicas (Siberian kale from High Mowing Seeds) only took 4 days! I think that’s a new spring record…not bad for a 55°F greenhouse.
With shiny vermiculite and peat beneath my fingers, I wish you successful solanaceous seeding.