Our Wisconsin growing season is too short for some vegetables to ripen or flowers to bloom if you wait to plant their seeds outdoors in May. Now is the time to start seeds of plants like tomatoes, peppers and annual flowers indoors.
Use a sterile soiless seed starting mix and a container that drains well. There are several options on stores shelves next to the seed starting mixes, or use egg or yogurt cartons or plastic cups with holes punched in the bottom.
Fill the container with seed starting mix to a ½ inch from the top and wet the mix thoroughly. Spread the seed over the mix evenly, or place one or two seeds in each compartment of a divided container. Cover the seeds lightly with more soiless mix to the depth suggested on the seed packet or use a toothpick or pencil to push the seeds to the proper depth. Press the mix firmly onto the seeds and water gently without disturbing the seeds. Use a fine spray or gently tip water off a small spoon onto the planting mix.
Cover the container with plastic. Purchased planting containers often come with clear plastic covers, but if you are using a homemade container, just slip it inside a clear plastic bag.
Place the container in a warm, bright place and keep it covered until the seeds germinate. Then remove the cover and water as needed to keep the soil moist. Turn the container once a day so the seedlings grow straight.
Seedlings first develop cotyledons, which look like leaves but are really food storage cells. Next, a set of true leaves forms. Now the seedlings should be transplanted to a larger container, either another flat with wider spacing, or individual containers filled with moist potting soil. Carefully lift the seedlings with a spoon or fork. Handle seedlings by their leaves rather than their stems – if the stem is crushed the seedling will die, but it can always grow a new leaf.
Use a pencil to make a small hole in the potting soil of the new container and place the seedling slightly deeper than it was growing in the seed flat. Gently press the soil around the roots and water well.
Transplants often droop or wilt but recover quickly if properly cared for. Keep them in good light, but not full sun, for several days and keep the soil moist.
Transplant the seedlings to the garden in mid-May. Before they go out, harden them off by placing the containers in a shady protected area for several hours each day, gradually moving them to the sun for short periods of time. Bring them indoors at night. Increase the length of time they stay in the sun each day for a couple weeks. Watch them closely to make sure they don’t dry out.
Choose a cloudy day to plant them out, or do so in the evening. Cover them with upended berry baskets, milk jugs, or floating row covers to keep them out of intense sun for a few days.