Garden Talk: Expert tips to keep your seedlings healthy and robust before transplanting

Hopefully, your garden seedling transplants are already sticking out of the ground. Now you need to give them a few things that will help them grow tough and ready for the wicked world of your real garden.

There is no substitute for real sunshine. The light spectrum of the sun on a partly cloudy day is still better than the full light from a grow lamp in your basement. So if we have some sunshine every day and temperatures in the 50s, your plants should spend the day outside. Plants are tender and can be shredded by Michigan’s March and April winds. Hopefully you have a warm corner in an inside corner on the south side of your home.

Rebecca Finneran, senior horticulture instructor at Michigan State University, says we need to be sure we have good air movement around our potted seedlings. Finneran warns that rot is the biggest threat to indoor seedlings. At the same time, she advises us not to let the tiny seedlings dry out. Once the plants have a nice, distinctive stem, I like to water just the soil around the stem. I don’t get the plant wet, which can cause fungus, disease, and rot.

The sign of a healthy Michigan transplant is a shorter, sturdier plant, not a leggy, limp plant. Strong sunshine is the first step in keeping plants shorter. The temperatures at which plants are grown make a big difference in terms of hardiness. Finneran would like us to keep the plants a little cooler. She recommends keeping the plants somewhere with temperatures below 70 degrees.

The scatter of the temperatures should be small. Find a spot in your home with consistent temperatures in the 60’s.

We need to gradually “harden” our grafts to prepare them for eventual strong, hot sunshine. Finneran says we should remember to always harden our grafts. She builds a mini greenhouse by spreading a clear plastic painter’s cloth over some patio furniture and setting the plants outside for one to four hours (gradually) for their “daily spa treatment.” When our temperatures rise above 50, the plastic tent underneath gets too hot. When it gets warm outside, lift the sides of the plastic to vent and let in some cooler air.

Remember that we can continue to fertilize our grafts following last week’s advice.

So check here the weather forecast every morning around 9am. I usually point this out when it’s going to be a sunny day. These are rare in Michigan during the winter, but will become more common in April and even more so in May. If you can keep your plants alive until the end of April, you will have an easier time getting them to grow in May.

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