The Q&A Archives: no success from seeds

Question: I have tried for 2 yrs to grow plants from seeds. Each year the seeds have sprouted, but the seedlings will not survive. I have used the recommended seedling mixture from my local nursery. When the plants emerge, I put them into a shady outside location for a couple of weeks. Then I put them into what should be their native environment for this area. At this point they seem to start growing. With a good rain they will fall down and may come back up. Then I see no more plants. I do not understand this.

Will you give me some advice?

Answer: Seed starting doesn't have to be complicated, but you'll need to devote some time and care to your seedlings before you can expect them to grow well. Here are some basic seed starting guidelines:

Some seeds require light to germinate, but most don't, so a warm, dark place, like the top of the refrigerator, will suit them quite well. Once they've germinated, your seedlings will need 14-16 hours of bright light each day. Regular fluorescent shop lights suspended 2" - 4" above the plants will provide adequate light.

You'll need the following equipment and materials to get started:

Seeds - flower or vegetable.
Growing medium - commercial seed starting mixes are light, loose, and sterile.
Seed flats and small pots.
Plastic wrap.
Watering can with sprinkling nozzle.
Heating cables - or warm place to leave flats until seeds have germinated.
Fluorescent shop lights or gro-lights.
Liquid fertilizer - a dilute solution of houseplantfertilizer will work.

Dump the potting soil into a large container. Mix in enough water to make the soil moist, but not soggy; if water drips out when you squeeze a handful, the soil is too wet. Add more potting soil, or wait until some of the water evaporates.

Place the moistened soil in the trays, filling them about two-thirds full. Plant seeds at the proper depth, usually 2-3 times the width of the seed. If seeds are planted too deeply, they'll run out of stored energy before the sprouts reach the top of the soil. If not planted deeply enough, the roots will push the seedlings out of the soil.

You can scatter the seeds on top of the soil, or you can carve furrows into the soil and plant seeds one at a time. Lightly cover seeds with moistened potting soil, label the trays with date and variety, and cover with plastic wrap.

Put the tray in a warm place such as on top of the refrigerator or near a water heater. If you have a heat-proof table or bench and some heating cables, you can lay the cables on the surface and put the trays directly on top of them.

When most of the seeds have sprouted, usually within 7-14 days, remove the plastic from the trays. If you leave it on too long you'll create a perfect environment for damping-off, a fungal disease that spreads rapidly and wipes out seedlings.

After the seeds have sprouted move the trays under a source of bright light. The light should be suspended 2" - 4" above the tops of the seedlings and should be left on 14 - 16 hours each day. Turn the lights off at night so the plants can rest. Water when the soil looks dry on top, but before it starts to pull away from the edges of the trays. Make the soil moist, but not soggy.

When the first set of leaves appear, it's time to thin. Save only the most vigorous, upright plants. Cull the weak and whimpy plants by snipping off their stems with scissors. If you pull the plants you'll disturb the roots of their neighbors.

Continue to monitor the light and moisture needs of your seedlings. Once the first set of "true" leaves appears, you can apply fertilizer to your new plants. Begin with half-strength liquid fertilizer, applied once a week. As the seedlings get bigger, you can increase the dose to full-strength, once a week.

When plants have developed two sets of leaves, they should be transplanted to individual pots. Prepare pots by filling two-thirds full with moistened potting soil, and making a hole in the center with your finger. Prick plants out of the trays with a plastic fork, carefully untangle the roots, and place each one in its own 4" pot. Water carefully so you don't dislodge the plants, and then return the pots to their source of artificial light.

Six to eight weeks after germination, your seedlings will be vigorous and lush. When the weather warms outside, harden them off in the following manner:
Set the seedling containers outdoors in a sheltered spot for a few hours each afternoon. Gradually increase the time they spend outdoors during the day, but bring them in at night. After about a week, they should be spending 24 hours a day outside. They then need to make the transition to direct sunlight. Begin by giving them morning sun for a few days. Then move them to afternoon sun for a few days. By the end of a week, they should be sufficiently hardened off to be planted in the garden.

Pick an overcast day or place them in their new homes late in the afternoon so they have a chance to adjust. They'll be stressed and may even wilt, but they should recover by the next day. Water them as you place them in their garden spots to make sure there are no air pockets left in the soil. Then step back and enjoy your new garden.

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