Ways to get a head start on planting for warm season
Are there any tricks to starting plants indoors before transferring them to the garden?
The first thing is to time starting your seedlings properly. It’s a common mistake for people to start too early.
I know we’re sick of this cold winter weather and we’re all anxious to get started on spring, but if you start too early, your plants will be leggy, soft and succulent, unable to support themselves and you end up buying transplants from the greenhouse this spring anyway.
To determine your approximate start date, choose a date you plan to move the seedlings outside (early May for warm season crops such as tomatoes and peppers and mid-March for cool season crops such as lettuce and broccoli) and then count back five or six weeks. That’s your date to plant the seeds.
The first trick to growing your own seedlings indoors is to start with clean and sterile pots or packs. Seedlings are prone to several fungi that can kill them off and the fungi can be introduced into your seeding through contaminated pots. Even though the plants that were growing in those pots last year didn’t appear to get one of these diseases, that doesn’t mean that the disease isn’t present.
You can reuse old pots by washing them in soap and warm water and then disinfecting them with a dunk in a 10 percent bleach and water solution and then rinsing with clean water. Many people start with new pots and trays because they’re clean.
You then want to fill the clean pots with a potting mix specifically made to grow seedlings. Use a seedling mix because it is formulated to provide maximum water holding capacity (so the seedlings don’t dry out) while maintaining excellent drainage and aeration (so the seedlings don’t rot). This is a delicate balance and using a regular potting soil can lead to one problem or the other.
Once the pots are filled (press the seedling mix down gently so it doesn’t settle so much), you’re ready to seed. Most seeds we plant are pretty small and they can’t be buried too deeply or they won’t germinate. The rule of thumb is to bury the seed no deeper than three times its diameter.
When they’re in, start watering. The trick to watering is to balance the need of the seedling for enough water so it doesn’t dry out without giving the plant too much water so it rots. It’s a tricky balance sometimes but using the seedling mix will make it easier. You’ll probably have to give the seedlings a light watering (using room temperature water helps) once or twice a day.
Put the pots in a warm spot. The warmer it is the faster and more consistently they’ll germinate. They don’t generally need any light at this point, but once they emerge from the soil, bright light is essential.
Many people are disappointed when they grow their own seedlings because they get long and leggy. Seedlings usually do this when they don’t get enough light. Depending on a big window the right light often doesn’t provide the levels required for good stocky growth.
The surest way is to hang some grow lights right over the seedlings to give them the light they need. These provide a complete spectrum of light wavelengths the plant needs, both red and blue light. Incandescent bulbs provide red but little blue while fluorescents give blue but little red.
I’ll emphasize again that the lights have to be right down on the plants. Depending on the bulb, in an overhead fixture won’t work.
The brightness of a light source decreases by a factor of the square of the distance. What that fancy talk means is that a light twice as far away will only provide one fourth the light. A light that’s three times as far away will only yield one ninth the light. The light needs to be close.
As the seedlings grow, they may need to be transplanted into bigger pots. At this point, you can use a good quality potting soil to grow them in. And there you go. A bit involved, but that’s how we do it in our greenhouses.