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Garden Propagation Tips

Sowing Seeds
Starting plants from seeds is one of the most common -- and economical -- ways to propagate. Check out the dozens of tips in this section to help you sow seeds.

Reuse household items like egg cartons to hold seedlings.
Reuse household items like egg
cartons to hold seedlings.

  • Watch the color of ripening seed pods, which is the clue to when seed is ripe. When dry pods turn from bright green to dull green or brown and succulent fruits turn bright colors, the seeds are mature and ready to harvest.

  • To keep ripening seeds from escaping when a pod dries and splits open, slip a net made from an old nylon stocking over the seed head. Secure it to the stem with a twist tie.

  • Keep dry seeds drier by refrigerating them. This works with both seeds you've collected from dry pods in the garden and leftover packaged seeds. Keeping these seeds in low humidity will encourage a long lifetime. Put collected seeds in dry envelopes. Keep packaged seeds in their original packets as long as they are dry. Enclose them in a sealed plastic bag or glass jar and put them in the refrigerator, where the air is extra arid. Avoid putting them in the humidified produce keepers.

  • When planting, label all seeds with plant and cultivar name and date sown. Because many seedlings look alike, facing an unlabeled flat would be a nightmare. Labels help you remember such things as which little green sprouts are the zinnias and which are the marigolds.

    The cultivar name lets you tell hot peppers from sweet peppers (very important!) and red pansies from blue pansies. Since cultivar names like Hungarian Wax pepper may be too long for short plant labels, come up with code abbreviations (such as "HW pep") and note them in your propagation records for future reference. Write on wooden or plastic tags with permanent ink.

  • Make your own labels out of milk cartons or plastic jugs instead of buying them. Simply wash them out, cut them into strips about 1 inch wide and 4 to 6 inches long, and write right on them with permanent ink or wax pencil.

  • Label like the pros. When planting in a flat, organize plant tags neatly so you can remember which plants they are referring to. If planting the flat with the long side closest to you, run rows of seeds from the front to the back, starting at the left side and ending at the right side. Insert a new label in the planting row each time you start using a different seed. This technique also works for flats of cuttings.

  • Sow perennial and wildflower seeds outdoors in raised beds or spacious nursery pots (the kind you get big flowers in at the nursery) and let nature get them ready to sprout. Hardy perennials and wildflowers often have a special defense called dormancy that keeps them from sprouting prematurely during a temporary midwinter thaw (which would be damaging when the frost returned). They require a certain amount of cold -- or alternating freezing and thawing -- to indicate when winter is truly over and spring has begun. The easiest way to accommodate the cold requirement is by putting them outdoors.

  • Instead of buying pots or cell packs, recycle household containers for starting seedlings. Try some of the following:
    • Egg crates or milk cartons cut lengthwise
    • Clear plastic bakery containers with lids that provide a greenhouse-like atmosphere
    • Yogurt cups
    • Cottage cheese containers
    • Plastic foam coffee cups

Some Perennials that Don't Need Stratification
There's no need for stratification for these plants:
Wash the containers out thoroughly with soapy water, then sterilize them with a solution of 1 part bleach to 10 parts water. Poke holes in the bottom to allow excess water to drain out.

  • Give certain summer blooming perennials a brief cold chill to synchronize their germination. Provide four weeks of cold, moist conditions (a process called stratification) to perennials such as asters, goldenrod, sneezeweed, and blazingstars before encouraging them to grow.
  • To stratify perennial seeds that require a cold treatment to germinate, sow them in a community flat of moist seed-starting mix. Label, then wrap the entire flat in a plastic bag and close with a twist tie. Set the flat in the refrigerator for the time indicated on the seed packet or in a seed-sowing handbook. When the recommended stratification time is up, move the flat into warmth and bright light so the seeds can sprout and grow.

  • If starting seeds in a window, take extra care to maximize light. Use a south-facing window that will receive sun all day. It should not be blocked by a protruding roof overhang or an evergreen tree or shrub. (Without a south-facing window, it's worth considering building a light garden.)

    Hang foil reflectors behind the flat to keep seedlings from leaning toward the sun. If the seedlings are sitting on a windowsill, make a tent of foil behind them, with the shiny side facing the seedlings. This will reflect sunlight and illuminate the dark side of the seedlings. They will grow much sturdier and straighter as a result.

  • Start seeds indoors under lights rather than in a window for even, compact growth. Seedlings must have bright light from the moment they peer up out of the soil. In climates with cloudy weather or homes without south-facing windows, sun may not be reliable enough. A light garden is an ideal solution.

    Set seedlings snugly under a fluorescent shop light. You could place seedlings on a table or counter and suspend the shop light from the ceiling over them. Or you could set up three or four tiered light stands. You can adapt ordinary shelves by attaching lights to the bottoms of the shelves and growing trays below each light. Put the lights on a timer set to turn them on for 14 hours a day and off again (one less job for you). You can't beat the results!

  • Make a mini-greenhouse under lights with a clear plastic garment bag. This traps humidity near seedlings, helping to protect them from wilting. To cover nursery flats full of seedlings, bend two wire coat hangers into arches and prop them in the corners of the flat, one at each end. Work the plastic over the top of the hangers, and tuck the loose ends in below the flat.It's even easier to make a greenhouse cover for individual pots. Slide two sticks (short bamboo stakes work well) into opposite sides of the pot. Then top with the plastic and fold under the pot.
  • Start seeds or cuttings in an old aquarium or clear sweater box to keep humidity high. Aquariums or sweater boxes are more permanent alternatives to the makeshift options above. They are particularly good for cuttings that may need more overhead and rooting room than seedlings.

    To reuse these containers, wash them with soapy water, rinse, and sterilize with a solution of 1 part bleach to 10 parts water.

  • Don't transplant seedlings into a larger pot until they have one or two sets of true leaves. This allows seedlings to develop enough roots to be self-supporting even if a few roots are lost in the process. It's also a time when seedling roots are fairly straight and compact, making them easy to separate from nearby plants.How can you tell when the time is right? It's not as simple as counting the number of leaves on the stem, because the seedling usually has an extra set of leaves called cotyledons or seed leaves. They emerge first and store food that nourishes the sprouting seedlings.When you look closely, you can see that cotyledons are shaped differently from true leaves. Squash seedlings, for instance, have oval squash-seed-shaped cotyledons that are easy to spot. But the true leaves are broad and lobed.
  • To avoid burning seedling stems with the salts on your hands or breaking an irreplaceable stem, handle young seedlings by the cotyledon or seed leaf.

Learn how to propagate by taking stem cuttings on the next page.

Want more gardening tips? Try:

  • Gardening Tips: Learn helpful hints for all of your gardening needs.
  • Annuals: Plant these beauties in your garden.
  • Perennials: Choose great plants that will return year after year.
  • Gardening: Discover how to garden.