Welcome interlopers
Every year mustard plants pop up in my back lawn, their dark burgundy leaves obvious against the fresh spring green of the grass. These are an ongoing legacy from a vegetable garden that once occupied this sunny spot.
I pull them up to give to the chooks or add the leaves to salad. If they take root in a garden bed, I’ll leave the plants to grow as they are handsome with flowers that attract pollinators and beneficial insects.
Plants that come up by themselves in the garden are known as volunteers (or weeds if they are unwanted!). They grow from seed from a previous crop. Not only are volunteers free, these self-sown plants often grow well. One of the pluses of volunteer crops is that they are often adapted to local microclimates and soils. Saving seeds from successful volunteers and re-sowing them can nurture and preserve these climate-adapted plants.
OTHER FREEBIES
Along with the mustard I also reap harvests from volunteer cherry tomato, Cape gooseberry, potato (lots and lots of potato), rocket, lettuce and parsley. I’ve also had delicious fruit from a volunteer nectarine tree that has “planted” itself against the back fence.
Pumpkins regularly sprout from seeds discarded in compost heaps. The warmth and rich nutrients in compost seem to encourage good germination and growth. Many people swear their volunteer pumpkins are the best they’ve eaten.
Last year I had a forest of self-sown brussels sprout plants. Some didn’t form good sprouts but produced a massive crop of shoots, which were delicious eaten as a green vegie. These brussels sprouts hybridised with other brassica plants that were growing in the vegie plot – perhaps broccoli – so it will be interesting to see what comes up this year.
One perplexing volunteer that appears in gardens is the kangaroo apple, an edible native. It is usually spread by birds and forms a tall shrub with small purple flowers that resemble potato flowers and elliptical fruit that ripens to orange.
RUN TO SEED
Of course volunteers don’t appear unless part of the crop is allowed to flower and form mature seed so it is important to leave some plants to keep the volunteers coming.
Allowing plants go to seed can bring interesting results but to enjoy crops that are the same as the parent plant, concentrate on growing open pollinated plants rather than hybrids and keeping plants that are likely to hybridise (such as brassicas) apart. The progeny from F1 hybrids usually reverts to one of the original parent plants, which may not be the best producers.
Volunteers are usually good to have, but they don’t always grow where the vegetable gardener wants them. They may pop up in the middle of a flowerbed or in a lawn like my mustard.
If the volunteer is in the right spot, leave it to grow, but if it has popped up where it’s going to be a nuisance, transplant it to a better site.
Also consider moving volunteers that are growing where the same crops grew before as the next generation may harbour disease.
Potatoes are found as volunteers as it is easy to leave small tubers behind after harvest or spread them via compost. These volunteers can help spread disease as they are not grown from seed but from the original tuber.
This is what happened in the 1840s in Ireland when potato crops were devastated by the fungal disease potato blight. With little genetic difference between crops that were simply regrown year after year from tubers left in the ground, potato blight was able to build up and the resulting crop losses were devastating.