Tips, tricks to starting seeds indoors before transplanting
Are there any tricks to starting plants indoors before transferring them to the garden?
The first thing to starting your own seed indoors is to seed it at the proper time. Over and over I see people get anxious and start it too early, which often leads to problems down the road.
Most seeds will take about six weeks to germinate and grow to a proper transplanting size. So, decide when you’d like to plant them outdoors and count back about six weeks to set your seeding date.
Next, start with clean and sterile pots or packs. Seedlings are susceptible to several fungi that can kill those tender little guys off and can be introduced into your seeding through contaminated pots.
Although 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 thoroughly with clean water.
What most people do is start with new pots and trays because you know they are clean.
You then want to fill the clean pots with a potting mix specifically made to grow seedlings, not just potting soil and certainly not garden soil. You want to use a seedling mix because it is specially 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 sometimes leads to trouble with 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 the seeds are in, start watering. The trick to watering is to balance the water needs of the seedling so it doesn’t dry out without giving the plant too much water to it rots. It’s a tricky balance sometimes but using the seedling mix makes it easier. You’ll probably have to give the seedlings a light watering once or twice a day.
Put the pots in a warm spot. The warmer it is, the faster and more consistently the seeds will germinate. One thing I like to do is to cover the seedlings with a “humidity dome.” This is a clear plastic dome that holds humidity (so they don’t dry out as quickly) and warmth in.
Your seedlings won’t need a ton of light when first planted, 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 because they don’t get enough light.
Depending on a big window often doesn’t provide the levels of light plants require for good, stocky growth. You usually have to hang some grow lights right over the seedlings to give them the light they need.
I’ll emphasize again that the lights have to be right down on the plants. Depending on the bulb, an overhead fixture won’t work because the brightness of a light source decreases by a factor of the square of the distance. That means 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 right there.
You also need an actual grow light. These provide a complete spectrum of light wavelengths the plant needs. Plants need both red and blue light. Incandescent bulbs provide red but little blue while fluorescents give blue but little red. Without a grow light you’ll still get long, spindly growth even if the light is down close to the plants.
As the seedlings grow, they may need to be transplanted into bigger pots. At that point you can use a good quality potting soil.
There you go. It’s a bit involved, but that’s how we do it in our greenhouses.