Starting your own tiny plants from seed is a little bit of work, but you’ll get a huge return on investment! The biggest advantage is that you’ll be able to plant the specific varieties of flowers or herbs you want, not just what you’ll find at your local nursery. Also, some crops, such as heat lovers like tomatoes and peppers, require a head start to reach maturity in certain parts of the country. So, in regions where the growing season is short, you’ll be able to get your baby plants in the ground immediately after the danger of frost is past. Knowing how to start seeds indoors is also a good excuse to get your hands in the dirt long before it’s warm enough outdoors!
Here’s what else you need to know about the process, including when to start seeds indoors, watering, light, and more. (And don't forget to check out our best backyard ideas and fresh landscaping ideas too.)
Give yourself enough time.
It can take from 3 to 15 weeks to grow a seedling big enough to move into your garden, says the University of Missouri Extension. Check with your local county coop extension service (find yours here) for the estimated last frost date in your area. To determine when you need to plant seeds indoors, read the seed package for how long it takes for a crop to mature, and count backwards from the estimated frost date.
Prepare your containers.
Seeds can be planted in any shallow container about 2 to 3 ½ inches deep with drainage holes. Plastic milk jugs with the tops cut off, paper cups, peat pots or shallow compartmented trays with plastic covers (sold in garden supply stores) all work well. If you’ve used a container before, the University of Maine Coop Extension suggests cleaning it with a solution of one part chlorine bleach to nine parts water to prevent potential disease contamination from previous plantings.
Buy a seed-starting mix.
Look for a fine-textured soil-less mixture (not a potting mix). Garden soil isn’t a good idea, because it may contain disease or weed seeds and tends to dry out too fast. Fill your containers ¾ full with the starter mix (use fresh every year!), water the mix, then gently press seeds into the surface. Read the label to see how deep to plant; typically, you cover the seed with the growing medium about 1 ½ times as deep as the seed’s diameter. Mist lightly, then cover with plastic wrap or the plastic dome lid that came with your tray.
Give the seeds enough light.
Place the containers in a warm location, about 65 to 75 degrees, for germination; avoid drafty windowsills. Once the seedlings pop up, remove the plastic or cover and move to a location with bright light. They need about 12 to 14 hours of light per day so they don’t become leggy and spindly. For best results, use a grow light set about 3" above the trays, and adjust height as the seedlings grow.
Feed your tiny plants.
Once the second set of leaves appear, water with a half-strength solution of liquid fertilizer about once a week (growing mediums have no fertilizer). Let the plants dry out a little before watering again to prevent damping-off, a common disease that causes the plants to shrivel at the base and fall over. Transplant the seedlings into larger pots in a soil-less growing mix to give them space to grow, but handle by the leaf, not the stem, to avoid bruising them, says the University of New Hampshire Extension.
Get the seeds ready to go outside.
To avoid transplant shock, acclimatize your seedlings by a process called “hardening off.” Basically, you slowly expose them to outdoor conditions to toughen them up. First, move them to a shady spot for a few days, then into sunlight for a short amount of time each day. Don’t put them out when it’s windy or colder than 45 degrees. After about a week or two, they’re fine to plant outdoors if risk of frost is past. One note of caution: Every spring is different, so it’s not a bad idea to wait a week past your area’s last average frost date to set out your new plants.
Keep a diary.
Write down what you planted and when to help you do better next year. Record the last frost date, and pay attention to what thrived and what wasn’t worth the effort for next year’s garden planning.
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