Planting

10 top tips for growing your plants from seed

Although it obviously does take more time, propagating plants from seed isn’t difficult if you choose the right varieties.

Seed Image

There is also a wider range of plant seeds available these days than seedlings. And better still many can be gathered from your own plants or those of friends and neighbours. Our 10-step guide will get you started.

1. Easy plants to sow

Large seeds such as sweet peas, nasturtium, dietes and sunflowers are easy to handle and not super-fussy about their growing conditions. Plants that self-seed easily such as alyssum, lobelia, euphorbia and Californian poppies are also a good bet.

2. Best seeds for collecting yourself
It’s possible to collect seed from all kinds of plants. Among the least trouble to propagate and harvest are cornflowers, daylilies, dietes, flax, libertia, marigold, nasturtium, nigella, rengarenga and
sweet peas.

3. When to gather seed

The best time to gather seed is when they are ripe at the end of the flowering season. Harvest seed on a dry and sunny day, choosing seedpods that have turned brown and can be easily split open or flower heads that are starting to dry and lose their colour.

4. How to collect seed

Choose healthy plants and cut pods or seed heads with clean and sharp garden scissors. Use a large paper bag to collect pods and seeds then separate them into smaller paper bags or envelopes labelled with the flower name and date. Store in a cool, dry and dark place, ideally in an airtight glass jar. Do the same with any foil packets of bought seed that you have left over.

5. How to germinate

Soil temperature is a key factor in seed germination with most flowers needing 20°C but some, like Iceland poppy and alyssum, germinating at lower temperatures. Most seeds don’t need light to germinate but there are a few that do so do your research before sowing. Moisture and air in the potting mix is also essential.

6. Best soil mix

You can use garden soil or standard potting mix to germinate seeds but your chances of success are not as great as they would be using a mix designed specifically for that purpose, containing the right balance of water retaining, aeration and drainage materials as well as nutrients. To make your own seed-raising mix combine two parts potting compost (commercial types are best as they shouldn’t contain the weed seeds or fungus that homemade compost often does) with one part fibrous material like coconut coir (pre-soaked), one part course sand or vermiculite and a little (less than a quarter part) of worm castings or sieved animal manure.

7.  Direct sow
Many seeds can be sown directly where you want the plant to grow, in fact some prefer it as they don’t like being transplanted. Good options for direct sowing include alyssum, aster, calendula, linaria, lupin, marigold, sweet peas, poppies, larkspur and wildflowers.

8. Sowing in pots and trays
Sowing seed in trays is a good way to protect tiny seedlings from weather, snails and other pests. You can also keep pots inside in winter until temperatures are warm enough for seedlings to survive outside and move them around to give them more sunlight. There are many products such as peat moss pellets
now on the market that make it easy to transplant seedlings.

9. Seed care regimen
Make sure seeds are not sown too thickly or too deeply, and that the smaller they are the more shallow the depth. Sometimes mixing fine seed with sand can help ensure they’re not sown too thickly. Seed mix must be kept damp (not wet) until seedlings emerge. Then water thoroughly with a fine, gentle spray every few days, ideally in the morning, making sure the mix never gets too dry. Cover with plastic or glass in winter for extra warmth but remove once seedlings come up. Gradually move into sunlight as they mature but don’t leave covered trays in direct sunlight or you’ll cook seedlings. Protect them from snails and other pests. Remember all plants have different germination rates, some only a few days, others can be over four weeks.

10. Transplanting out 
Once seedlings have at least two sets of leaves and are about 7-10cm high, you can plant them out into bigger pots or the garden. Moving seedlings outside to ‘harden off’ for a week first is a good idea. Prepare the area for planting, removing weeds and big clods and fertilise. Water seedlings well the night before. Make a hole deep enough for the depth of the root ball and twice the width of the plant. When removing from pots or trays hold seedlings by the leaves and cut through soil in between each one. After planting water well and sprinkle snail bait. If you’ve planted them in a sunny spot you may need to place shade cloth over seedlings for a week or so.

MORE TIPS
When sowing seed directly into ground hoe soil about two weeks beforehand to make it nice and crumbly. This also encourages any weeds in the soil to germinate so they can be removed before your seedlings pop up.

Words by: Carol Bucknell
Illustratrion by: Shani Luckman

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