The Q&A Archives: Straggly Seedlings

Question: I read in one of your other answers that too little light and too much heat can cause tall, thin, straggly seedlings. I place my grow lights very close to the containers when the seeds are first started and them move them up every so often.
I keep my seedlings in the basement. I'm wondering: can the seedlings be getting too much heat from the lights? How often should I move the lights up? I start the seedlings with a heat pad but remove it as soon as there are little "green growies". Should I eliminate the heat pad altogether? Can you give me any other advice?

Answer: Because indoor lights aren't nearly as bright as sunlight, the guideline is to keep the lights 4-6 inches from the top of the plants, adjusting that as they grow. In other words, maintain the same distance as the plants grow, moving the lights up as necessary. You didn't mention how long you leave the lights on. They should be on 16 hours a day and turned off at night. Putting them on a timer is helpful to maintain a schedule. Heat pads are good to help germination, but once the seedlings are up and growing you can turn it off.

If you start your seedlings in a sterile soilless mix, they will need to be very lightly fertilized to provide nutrients. Start fertilizing after they have developed a set of true leaves. Use a diluted formula about once a week. After they are transplanted to a real soil mixture, increase the time between fertilizing to about two weeks.

Seedlings won?t thrive if crowded, as they require both air circulation and light. When thinning crowded seedlings, snip the extras with scissors at the base of the plant rather than yanking them out. This helps prevent disturbance to developing root systems. I hope this info helps!

« Click to go to the homepage

» Ask a question of your own

Q&A Library Searching Tips

  • When singular and plural spellings differ, as in peony and peonies, try both.
  • Search terms are not case sensitive.

Today's site banner is by ge1836 and is called "Sempervivum Henry Carrevon"