Growing from seed is intensely satisfying. As well as the pleasure of nurturing from tiny seed to sturdy plant, it’s a cheap way to fill the garden with blooms. Vandra Costello shares her guide to getting started.
Annual plants are those which grow, flower, and set seed and die all in one year. They are synonymous with summer – think of cornflowers, sweet peas, love-in-a-mist, and sunflowers. If you start your planting in spring, you will have armfuls by summer.
What you will need:
• Seed trays – the ones with compartments are the best. Cardboard ones are even better as they can be planted straight into the garden. For sweet peas, use the centres of old toilet rolls
• Seed compost
• Horticultural sand or vermiculite (optional).
The other vital components for successful germination are warmth, fresh air and moisture. The next obvious step is to select which seeds you want to grow. Remember to think about colour, height and flowering times when planning. The seed packet will be marked as “perennial”, “annual” or “half-hardy annual”. When you want plants that will flower this year, it is the latter two categories you need to buy.
For many seeds – true annuals – the warmth of the sun on the earth as the days grow longer is enough to spur on germination. To sow these, you simply need to weed the area where you want the plants to grow, then rake the soil to break it down until it has a fine and even surface. Then you simply broadcast the seed. The problem with this method, especially for new gardeners, is that you may then not know what is a weedling and what is a seedling once growth starts, so you may like to sow in seed trays, which you can leave outdoors. Others, the “half-hardy” annuals, need an extra boost of heat by being grown indoors until all danger of frost has passed, when they can be transferred out of doors. You do not need a greenhouse, fancy heated pads or any special kit – a sunny windowsill will do, or a space on any surface near a window.
Some seeds need a bit of special treatment before sowing. For example, sweet peas have a very hard shell and need to be soaked for a few hours or overnight before planting. The seed packet will provide instructions.
Fill your seed trays with seed compost. The reason we use seed compost is that ordinary compost is too rich for young plants. Water the compost before you start sowing. How you sow depends on the size of the seed. If the seeds are large, like peas, beans or sunflowers, pop one seed firmly into the soil of each module or pot. For tiny fine seeds like opium poppies or snapdragon, you will need to sprinkle them very carefully on the top of the soil, trying not to get too many in one spot. I usually cover fine seeds like this with a dusting of horticultural sand or vermiculite to hold them in place.
If you are like me, you will then check on the seed trays non-stop, looking for signs of germination. This is where patience is required. Some seeds will start incredibly quickly, while others may take a few weeks.
When germination starts you will notice that the seedlings all have little leaves; these may be oval or rounded but these first leaves are called cotyledons – they are not the plant’s first true leaves. You will notice that once the tiny plant begins to grow, new leaves, which look more like the adult plant’s leaves, will develop. When this happens, you can start to thin out the seedlings. When you have sown a fine seed, you may get too many plants growing in close proximity. They will fight for space and nutrients and crowd each other out, so you need to take out the spindliest plants and throw them away, leaving a few healthy-looking seedlings.
When these have grown a bit and put on a few more leaves, you can transfer them to larger individual pots; this is called “potting on”. With half-hardy annuals, you then have to do what is called “hardening off”. This means getting the plant accustomed to life outdoors by putting the plants outside during the day and taking them in at night for a week or so before planting outdoors in early June. Remember to look after the plants during the summer by regular watering, feeding and deadheading to ensure they keep flowering all summer long.
Annuals to grow
• Cosmos
• Nicotiana (tobacco plant)
• Tagetes (French marigold)
• Zinnia
• Amaranthus
• Nigella
• Verbena x hybrida
• California poppy
• Shirley poppy
• sweet pea
• sunflower
• cornflower
• snapdragon
This feature originally appeared in the spring/summer 2024 issue of IMAGE Interiors. Have you thought about becoming a subscriber? Find out more, and sign up here.
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