Sowing Seeds Indoors

Gardeners often need to give plants a critical head start by germinating and growing seedlings in the warm indoors in early spring. Then when it warms up outdoors in late spring, we can plant out sturdy, well-established seedlings to bear fruit before cold weather sets in. Favorites like tomatoes and peppers are both plants that need a long warm growing period to set and ripen a good crop. Except in the most tropical areas, all U.S. summers are too short for them to complete their fruiting cycles before summers end if started directly in the ground, since seeds won’t germinate until frosts have ended and weather warms up.

When to sow seed indoors? Generally, the time to start your seeds is about 8 weeks before the last expected spring frost date in your area, planting the seedlings outdoors about 2 weeks after that date.

Another way to figure is to plan on setting out sturdy seedlings in the garden when night temperatures stay in the mid-50 degree range both day and night. Count back and sow seeds 6 to 8 weeks before that date normally arrives. If you don’t feel confident about timing, consult an experienced gardening friend, or ask at a good garden center.


Your planting containers should be at least three inches deep, with small holes for drainage. You can use plastic yogurt or cottage cheese containers, 3 or 4 inch plastic plant pots or half-gallon milk cartons cut lengthwise, all with drainage holes punched in the bottoms. I don’t recommend reusing egg cartons or old nursery packs as they don’t hold enough soil volume and dry out too easily. Buy and use a good quality seed starting mix, available from any good nursery or garden center.

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In a big bucket, add water slowly to the seed starting mix and combine well. You want it to be thoroughly moistened but not soggy – about the consistency of a wrung-out sponge throughout before you fill your containers. Fill each container to an inch below the top and tap it on the tabletop to settle the mix. Use a plastic or wooden marker with the variety name and sowing date and slide it into the container. With the side of a pencil or chopstick, make a seed furrow about 1/4 inch deep and carefully drop in individual seeds about an inch apart. Sift some more starting mix between your hands to fill the furrows and firm gently to be sure the seeds have good contact. Use a spray bottle to water the seeds in with a fine mist.


Germinating and growing

. Many warm weather plants like peppers and tomatoes need 80 to 85 degree conditions to start germinating. Put the containers in a warm place where they’ll get bottom heat, such as on top of the water heater or refrigerator. Keep the container moist, but not soggy. You can cover it with plastic wrap or an old piece of rigid clear plastic to conserve moisture if you like, but be sure to pull it up to check daily to be sure they aren’t drying out. Water as necessary with a very gentle spray of water. If container should get too dry, you’ll need to set it in a pan of water so it can soak up water again from below. Expect germination to take 5 to 10 days for tomatoes and 5 to 14 days for peppers. (Don’t keep your containers in the windowsill during the germination period; cold air at night will affect germination.)

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Check often! Just as soon as any baby seedlings begin to emerge above the soil level, its critical to give them light right away. Remove any covering immediately and provide a strong light source. While a south-facing windowsill is traditional, its far from ideal. I like to start my containers from the beginning under grow lights or a fluorescent shop light suspended from chains with cup hooks so I can move the lights up as the plants grow. Suspend the light just 1 or 2 inches above the seedlings and it will provide both light and warmth. (Once germinated, seedlings will grow happily at 70 – 80 degrees).


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