Cape Town - Spring has arrived, and now is time to sow “easy-to-grow” seed varieties that flower in summer.
There are two ways to sow seed this summer. The first is to sow seed directly into flower beds (otherwise known as sowing in situ).
The second way is to sow seed into seedling trays and then transplant seedlings into the garden. Germination rates have always been better if you sow seed into seedling trays, although sowing seeds directly into flower beds is far easier and more convenient.
Not all seeds can be sown directly into flower beds. On the back of a packet of seeds you can find out which grow best in seed trays, and which can be sown directly into flower beds.
Sowing seed in trays:
For growing in seed trays, sow the seeds as per instructions into trays filled with a good seedling soil mix. Use a sterile growing medium for your seeds, not ordinary garden soil.
Good seedling or potting soil mixes are available at garden centres. Alternatively, you can make your own soil mix from two parts fine compost and one part river sand, but sterilise it by pouring boiling water over the container filled with soil.
To sterilise the soil, place a plastic tray in a microwave on high for one minute, or place the soil on a sheet of aluminium foil placed on a baking sheet, cover the soil with foil and bake for half an hour in the oven at 150°C.
Very fine seed, such as petunias, phlox and lobelias, can be mixed with an equal quantity of maize meal or fine river sand to ensure a more even distribution. Use a sieve to sprinkle soil lightly over the seeds.
The general rule is to cover the seed with an amount of soil equal to twice its thickness. But some flowers – including snapdragons, impatiens, alyssum, lobelia, petunia, diascias and phlox – need light to germinate and should not be covered at all. Sprinkle seeds thinly on top of the growing medium.
Most seeds germinate at about 21°C, so place the seed trays in a warm protected spot. If the seeds require darkness to germinate, place newspaper over the seed tray until the seeds have germinated. Read the seed packet to find the germination temperature.
The key to success is to keep the soil moist at all times, watering gently by hand with a watering can with a fine sprinkler.
Putting the seed tray in a clear plastic bag and sealing it, or covering it with a sheet of glass will keep the seeds warm, and also keep the soil moist.
The biggest mistake that gardeners make is to plant seed too deep and allow seeds to dry out; the soil needs to be moist at all times. Watch out for crowding when the seedlings appear; transplant seedlings evenly across the flower bed.
Directly into the garden:
The key to in situ sowing is to prepare flower beds and choose varieties carefully. Add liberal quantities of compost, manure or other organic materials to the soil in your flower bed to improve the water holding capacity of the soil. Moisture is the key to successful seed germination.
Level the composted soil and wet it thoroughly. Then sprinkle the seeds evenly across the soil. Cover the seeds with a light (1mm thick) sprinkling of top soil or seedling soil, and then soak the bed with a gentle sprinkler.
If you’re a beginner gardener, choose varieties that can be sown directly into prepared flower beds such as zinnia, nasturtium, candytuft, alyssum, portulaca, marigold or cosmos. Seed companies have also prepared packets of mixed annuals for either sun or shade.
Take into account the height of each annual when it is fully grown – details are on the back of the packet. Plant the tallest at the back of a flower bed, those of medium height in the middle, and the shortest at the front. Many low growing annuals make attractive edging plants along the front of a border.
Colour annuals you can sow this summer with mature heights include:
Low-growing annuals (Height 15 - 30cm):
Try alyssum, aster, balsam, begonia, candytuft, dwarf cosmos, blanket flower (or gaillardia), gomphrena (or satin flowers), marigold, nasturtium, portulaca, petunia, statice, viscaria or zinnia.
Medium growing annuals (Height 40 - 60cm):
Try balsam, candytuft, clarkia, dahlia, gloriosa daisy , gomphrena, marigold, nigella, statice and zinnia.
Tall growing annuals (Height 60 -80cm):
Try aster, cosmos, gloriosa daisy, gypsophila, helichrysum, hollyhock, lavatera, marigold and zinnia.
Very tall growing annuals (Height over 80cm):
Try cleome, cosmos, helichrysum, hollyhock, larkspur and white lace flower.
If you would like to paint a picture with flowers in your garden this summer, consider a particular colour scheme.Pink, blue and white plantings are always attractive, as are yellow and blue or mauve. For sheer drama go for red and white. Or blend together red, orange and yellow to create a “sunset shades” combination.
What vegetables can be sown directly into beds this month?
Bush and climbing beans, cabbage, carrots, pepper, pumpkin, lettuce, radish, squash (patty pans) and tomatoes.
Weekend Argus