Plan to Think Spring
Growing seeds indoors ahead of planting time can result in earlier produce and posies
By Deborah Jeanne Sergeant
Flex your green thumb early if you want to get a jump on planting this spring. Starting seeds indoors can begin before you may think. But don’t start stirring the potting soil too soon.
“The inclination is to start too early,” said Marci Muller, horticulture team leader with Monroe County Cooperative Extension. “Especially if you’re growing not in a greenhouse setting and maybe not with a lot of extra light, they will get ‘leggy.’”
This means that plants will grow long stems but may not leaf out and bear as much flowers or produce as they should. At cooperative extension’s test plots, Muller and her associates start numerous seeds early, as the Northeast’s growing season is so short.
The very earliest are cold-tolerant plants by early February, such as parsley, leeks and onions (although Muller has concluded that onions grown for sets result in a better product.
Toward the end of February or beginning of March, she plants things like broccoli, cabbage, cauliflower, collard greens, collard greens. Later in the same month, it’s time to start eggplants and peppers. By early April, start warm weather loving plants such as tomatoes and basil.
“One thing people may not be aware of with seeds initially is they don’t need to be in a particularly warm setting,” Muller said. “If you can give them some bottom heat, the room can be on the cool site. They make mats you can set your flats on to get them to germinate. Once you have growth on the top, they can be in a warm room with lots of light.”
Usually, south-facing windows offer the most sunlight.
As to how deep to plant seeds, follow the directions on the seed packets. Muller said that as a general rule, the larger the seed, the deeper it must go into the soil. Using a seed starter mix means that the seeds will have readily available nutrients. Muller doesn’t fertilize plants until they’re a few inches tall, and then only light fertilization if needed.
“Avoid a high nitrogen fertilizer,” she said. “Nitrogen pushes growth and you don’t want to push it while it’s growing inside.”
She said that most people growing use a seedling tray and sow plenty of seeds since most of the time, growers don’t receive 100% germination.
“You want seeds moist, but not sitting in water,” she added. “Keep soil damp by misting daily rather than pouring water in. Once the plants come up, especially if you transplant them into a larger container, water them once to twice a week.”
Rotating the containers can help the plants grow straighter and with ‑ stems. Muller also said that using a fan on low can help prevent fungal growth and strengthen the stems.
After plants are established, they can be transplanted into a larger pot. Determining this relies on evaluating if the root structure is large enough to hold the plant upright and if the top is large enough to support growth.
Samantha Dattilo, a business partner at Stem in Rochester, advised starting seeds indoors soon enough so that they will reach maturity outdoors before frost, but not so soon they cannot be easily transplanted when ready—a determination she calls “seed math.”
“When you’re going to transplant outside, acclimate them first,” she said.
This involves taking plants outdoors for a few hours daily and gradually increasing their time outside. The soil temperature matters. Check out your soil temperature at National Weather Service’s site www.weather.gov/ncrfc/LMI_SoilTemperatureDepthMaps.