Self-seeders You'll Never Have to Sow Again

27 August 2015, written by Ann Marie Hendry

It happens every year – I take my eye off my rocket or my lettuce for a few days, and before I know it they’re spewing out bouquets of bright yellow flowers and the leaves have become unpalatable. It seems that some plants are simply programmed to reproduce themselves on schedule, no matter what I do to try to improve their growing conditions.

Self-seeding plants are in fact an essential element of self-sustaining permaculture gardens, so I’ve decided to take a leaf out of the permaculturists’ book. Instead of despairing at another bolted crop, I now look on the bright side and think of it as nature helpfully simplifying my sowing schedule.

Lettuce starting to send up a flower stalk

How to Manage Self-seeding Plants

When an annual or biennial plant flowers, or ‘bolts’, it’s the beginning of the end for that plant but the beginning of the beginning for its offspring. When the flowers have passed, allow the seeds to ripen on the plant. The seedheads will become dry and brittle, and when the time is right the plant will shower its seed onto the soil. No seed collecting (or purchasing) required!

If you’d prefer the seedlings to grow elsewhere next year, simply cut off the seedheads and shake them where you want them to grow. Rub the dry seedheads between your hands or crush them underfoot, then lightly rake them into the soil and give them some water, using a watering can fitted with a fine rose to avoid washing the seeds away. Once the seedlings have emerged, treat them to a mulch of compost or other organic matter to help suppress weeds and retain moisture. Water them as you would any other seedlings. Thin them as they emerge until they’re at the spacing you need.

Alternatively you can wait until the seedlings have developed their first true leaves (the first adult leaves that follow on from the initial 'seed' leaves) in spring and then transplant them, retaining a plug of moist soil around their roots to minimise root disturbance. This method makes it easy to arrange the transplants into orderly rows or blocks without unnecessary gaps, which improves access for hoeing between plants and avoids overcrowding.

Make sure you know what the seedlings look like so that you don’t accidentally hoe them off along with the weeds. We’ve all done it!

Plants That Reliably Self-seed

Plenty of common edibles are excellent self-seeders – rocket, Oriental leaves such as mustard, lettuce and radishes all readily self-seed. Herbs such as chamomile, coriander and dill will flower and self-seed easily. In warm climates you may have success with self-seeded tomatoes and tomatillos, which can even resprout from the composted fruits – but if your tomatoes suffered from early or late blights do remove the ‘volunteer’ plants to avoid transferring the disease onto the next crop.

Biennial crops such as carrots, parsnips, parsley and kale will grow leaves (and roots) in their first year. If left unharvested they’ll flower in the second year, providing a much-needed source of early pollen and nectar for insects before they give up their seed.

Don’t forget flowers either – annuals such as cornflowers (bachelor’s buttons), calendula, nasturtiums and poached egg plant, together with biennials such as foxgloves, honesty and teasel are all robust self-seeders that are loved by wildlife too.

F1 hybrid varieties are unlikely to come true from seed. You’ll get best results with open-pollinated (sometimes called heirloom) varieties, which produce seedlings of the same variety. However if you’re growing more than one variety of the same plant you might find you get an interesting cross between the two, for better or worse!

Weedy Self-seeders

Plants that sow themselves can be a great help, but there are a few you need to keep a watchful eye on to prevent them from taking over your whole garden. For instance chives, garlic chives and borage all shed plenty of seeds, so seedlings will pop up reliably – too reliably! Feel free to let them flower to feed the insects, but to prevent them from self-seeding be sure to clip off the spent flowers or seedheads before the seeds ripen.

Be ruthless. If any self-sown plant outgrows its allotted space, remove it as a weed.

Allowing plants to self-seed saves me a packet on packets of seed, while freeing up valuable greenhouse space at spring sowing time too. The air is abuzz with hoverflies and other pollinators in my vegetable garden, who certainly appreciate all that extra pollen and nectar. All this, and I get to enjoy more gorgeous flowers in my garden for no extra effort!

What are your favourite self-seeding crops or flowers? Drop us a comment below and tell us. Don’t forget to let us know where in the world you are too.