Seedlings and Light
Answered by: Inge Poot
Question from: No Name Given
Posted on: October 16, 2002

I’m rather confused on how to introduce plants to the amount of sun they like and hope you can help me.

I read that seedlings should be kept moist and in the sun. Wouldn’t the sun dry them out rather quickly and kill them? Or do you put the plant in dappled shade until it’s larger and doesn’t need to be kept moist, or is it some other method? Also, how quickly should they be introduced to their own sunlight needs?

There are various stages in seedling care that may need different strategies.

Seeds vary a great deal in their requirement for light or lack of light to initiate germination. Our seed packets tell you if the seed bed has to be exposed to light or has to be kept in the dark. If we don’t mention it it means it does not matter. Depending on your conditions you will have to find a way to keep the seed bed/flat damp, or the seeds will die often before you see any evidence of germination. A saucer under a pot of seeds refilled with water soon after it is taken all up by the soil is one way. Frequent misting with a fine mist nozzle is an option if you are around most of the time and have the time to do it. If you plant the seeds out of doors during the hot summer, it may mean having a mister going over the seed bed for some hours during the hottest part of the day. However, out of doors the sun is usually strong enough that providing dappled shade with a light covering of evergreen bows, will provide enough light to let seeds that require light to germinate come up well, but it cuts the wind enough over the seed bed that it dries out much slower. Placing a seed flat near the edge of a tree’s canopy also provides the dappled shade you suggested and should work well.

Once the seeds have germinated it is better to gradually cut back on the water to encourage the roots to grow deeper and therefore become more drought tolerant. Also damp off organisms have less of a chance if the soil is drier.

If you have started the seeds indoors, you will have to accustom the seedlings to stronger light gradually, but increase the light as soon as possible to prevent the seedlings from producing thin weak growth that will be very difficult if not impossible to harden off. Since a large percentage of herbs will need full sun to do their best, such seedlings should be shifted to an unobstructed south window as soon as they germinate and then to the out of doors as soon as possible, if that is what you plan to do with them. Out of doors start them in shade and take two weeks to gradually move them into full sun and after a week in full sun you can transplant them into their permanent spots in the garden. In general, during all this moving, water enough to keep the roots moist but not permanently soggy. Water especially carefully after transplanting. If the sun is very strong a bit of shading with evergreen bows or even newspaper is well advised. Remove the shading once the plants start growing again – usually after a week.

Applying a mulch around the plants as soon as they are large enough to make that feasable will cut your later watering chores by a great deal.

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