The winter solstice occurred yesterday at 7:04 AM - the shortest day of the year; last night, the longest night. It's time to start tomato seeds.
We sell organic garden seedlings at farmers' markets here on the Central coast of California. By March, many of our customers are eager to get a tomato plant into the ground. By April, they feel it is a necessity. By May, they are in a frenzy. To accommodate those who hope to beat the cool temperatures of winter, we start our first seeds on the day of the Winter Solstice. Here's how we do that:
We have a seed room - formerly, a one-car garage - that has been fixed up with shelving and hot water heat tubes running under the shelves. A circulating pump keeps hot water flowing through the tubes to maintain a temperature of 78 degrees 24 hours each day. The fluorescent lights above each shelf add warmth to the shelves above and in total we can accommodate 68 plug trays. Each tray has room for 200 seeds. That would be a total of 13,600 little seeds, each in their own plug of a sterile peat/perlite mix on a cozy little shelf. (I should mention here that that cozy little shelf is very attractive to cats so we have caged the shelves to discourage feline napping on warm plug trays!) The lights come on automatically for 14 hours each day, but the watering is done by hand and can take over an hour when the shelves are full.
At that temperature, it takes a tomato seed about three weeks to emerge and develop to a size suitable for transplanting into a three-inch pot. In the winter months, we often leave them a little longer before moving them up and out.
A tomato plant is a hardy little thing and most will survive the transplant from the plug tray into the larger container. They spend another day or two on the warm shelves and then move into the greenhouse. There they receive full sun, heated tables - also warmed by tubes of hot water - and good air circulation. The soil temperature has decreased from 78 degrees to the 50-60 degree range.
A well-established seedling will tolerate transplant into garden soil warmed to 50 degrees. It may not flourish immediately, but it will be well on its way to vigorous spring growth as soon as the soil warms to 60 degrees during the day.
So, if you have a nice protected garden area that receives at least 6 hours of daily sun, you can try transplanting cool weather tomato starts in mid-March. Beware cold snaps, drenching and prolonged rain, hail, and other spring surprises. Try covering the plants with Reemay floating row cover and keep the soil warm with black plastic mulch.
Next blog will discuss specific early tomato plants.