You know it’s spring at Harlow Farm when the greenhouses open up and we start seeding. We always start right around March 1 because, historically, it always seems to work out that we’ll be able to start transplanting in the fields in six weeks time.
First is kale and lettuce. In this round, we seed 65 98-cell trays for each variety of lettuce we grow. The seed is “pelletized;” each seed is coated with an organic clay, making it perfectly round so it will fit into the seeder. That’s because putting more than one seed in a cell doesn’t work — you end up without a head of lettuce.
Our kale is seeded using a vacuum seeder, which holds each tiny seed in just the right spot, using vacuum, to drop into a prepared tray. We seed 175 trays of 200 cells each of regular kale and another 175 trays of lacinata kale.
The seeds are planted in potting soil from Vermont Compost, a mixture of peat and compost, with a little vermiculite added for aeration. We mix the soil, along with some green sand, bone meal, and blood meal for fertilizer, in a labor-saving machine that also fills the trays. After seeding, each tray is covered with vermiculite, which helps retain moisture and prevent disease during the crucial first few days until the seeds germinate.
It’s also critical to keep the greenhouse environment at the right temerature — 60 F. during the night and 75-80 F. during the day. We strive for slow, even growth that produces a good root system.
Keeping those nighttime temps high enough is a challenge during the cold spells. But the greenhouses are heated by thermostatically controlled gas heaters, backed up by wood-pellet heaters. And just in case the heat goes off during the night, a local high school student has invented an alarm system that rings our cellphone when the greenhouse temperature drops below 40 F. Technology at work!
Seeding lettuce goes on every week through the first of August — during June, we seed twice weekly — giving us a steady supply of lettuce transplants through the season.