February 26th, 2009 Sow Much Fun! Tips for Growing Plants From Seed
Annuals grown from seed by homeowner
If you’ve never started seeds indoors, here are some tips to help you succeed.
Sterilize! Use sterilized seed starting mix (not potting mix or garden soil), and sterilized flats and pots. If you are re-using some of last year’s flats, wash them with a bit of bleach in warm soapy water, rinse well and allow them to dry completely.
Organize! Have everything ready before you begin sowing the seeds – flats, pots, labels, marker, spray bottle of room temperature water.
Fill the containers with the seeding mix. Water with warm (not hot) water. Allow it to drain and water again if necessary. The seeding mix should be moist right to the bottom of the container.
Make up labels. Using a waterproof marker, write the name and variety of the seeds on the front of the label. Write the date you sowed the seeds on the back.
Not all seeds germinate under the same conditions. Some require light to germinate, some complete darkness, some a light covering of starting mix. Some need to be treated to a period of cold before sowing (place those is the freezer or fridge prior to sowing). The back of the seed packets will give that information. Separate the seed packets into different piles according to their germination preferences. Sow seeds with the same requirements, in the same flat.
Sow the seeds according to the instructions on the seed pack or in the seed catalogue.
Insert labels after each variety is sown.
If you are covering the seed bed with starting mix, mist with the top of the seed bed with the spray bottle. The seed bed should be moist, not wet.
If the instructions state complete darkness is required for germination, cover the flat with black plastic. Otherwise, cover with a clear plastic flat cover.
Set the flats in a warm, draft free space to germinate.
Keep the tops of the seed flats moist by misting with the spray bottle. Depending on how hot and dry your house is, you may have to mist the flats two or three times a day. Note: If you use a watering can, you run the risk of flooding the seed bed and washing away the seeds.
The minute you notice the seeds have begun to germinate, remove the sheets of plastic if used, and replace with a clear cover.
The closer the seedlings are to the light source, the better. Too far from the light, the seedlings will become spindly. Avoid placing the flats in direct sun as the seedlings, being very tender at this stage, can fry or become sunburned. Keep the flats misted.
When the seedlings have two sets of true leaves on them, fertilize them with a 10-52-10 starter fertilizer applied at half strength. (At this point you can begin using a watering can.) Fertilize once a week, until the seedlings are growing well.
When the seedlings begin to reach the top of the plastic cover, remove it.
When the seedlings have several sets of leaves on them, switch to 20-20-20 water soluble fertilizer for two applications.
After that, begin using 15-30-15 fertilizer on flowering plants and 20-20-20 on foliage plants. All fertilizer applications should be at half strength.
If you notice flower buds forming, resist the temptation to let them develop. Until the seedlings are ready to plants outdoors, you want their energy concentrated on producing strong foliage and roots, not flowers.
Good air circulation, clean containers, and sterilized seeding mix all help prevent damping off and other diseases from infecting your seedlings. As always, avoid wetting the foliage when you water.
