Friday, February 13, 2009

Seedlings in the House: Tomatoes and Peppers

When the weather is as nice as it has been for the past week or so, gardeners get the seed-starting “bug.” This is okay as long as adequate (10-12 hours) light is available for the seedlings, but when the only light available is the sunlight streaming through a south-facing window, it is better to wait a couple more weeks before starting those tomato and pepper babies.

When not enough light is available, the seeds will germinate, but the plants will grow to be unusually tall and scrawny. In the botanical world, such a plant is called etiolated. This condition is bad for a couple of reasons. One is that the elongated, extra-slim stem just won’t be strong enough to withstand much pressure, like a strong rain or windstorm. The plant could be knocked to the ground and damaged, possibly beyond recovery, when transplanted outside.

Another is that such a plant, having been deprived of adequate light, may also have a weaker root system than a plant that has received more light. According to my (ancient! copyright 1974) freshman Botany textbook, some substances that promote root growth, such as the vitamin thiamine, are actually formed in the leaves, and then transported to the root zone where they do their good work. A plant that has not had adequate light will have less leaf area (pathetically small leaves), so may be producing less root-growth-factors than are needed to support a healthy plant.

This is probably more than anyone wanted to know, but the point is that, unless good light is available for starting seeds of tomatoes and peppers, it is best to resist the seed-starting bug until six weeks before the last frost date, as suggested on most seed packets. In this area, that date is 15 April. That means that the earliest pepper-and-tomato starting time is 1 March. Luckily, that isn’t too long from now.

Even with the 1 March start date, the little plants will not be as sturdy as professionally grown plants available for purchase in many stores; however, they will be good enough, and setting them outside on warmer (above 60 degrees Fahrenheit) days will help. I know that lots of people transplant their tomatoes and peppers to the garden on 15 April, but the weather here is unpredictable.

We have had freak freezes past that date. To be safe, and to give peppers, especially, the warmth they grow best in, it is generally recommended that these plants not be planted outside for another week or two beyond that date. However, if the weather forecasts are all for warm and continued warm weather on 15 April, it is probably safe, for those who are impatient, to transplant to the garden.

For those who have a very bad case of the seed starting bug, a set of fluorescent lights can provide enough supplemental light that home-grown seedlings will be fine, even starting this early. I have fluorescent lights over my seedlings, and I use the lights in the early morning and in the evening when the sun isn’t shining, and on cloudy days. An example of a home-built seed starting table is here at the Simple, Green, Frugal Co-op blog.

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