Problems and Benefits of Garden Weeds
Problems and Benefits of Garden Weeds
After identifying the weeds in your garden, you need to decide when and why they are a problem — or indeed whether they are a problem at all. Not all weeds are bad all of the time, and it makes sense to concentrate your efforts where they are most needed.
Weeds have an adverse effect on garden plants when they start to compete for water, nutrients and light. This can stunt plant growth and cause loss of yield in fruit and vegetables. Slow-growing, slender-leaved crops such as onions are more susceptible to competition than vigorous crops with broad leaves, so give them priority when weeding.
Competition is not the only problem, for weeds can also harbour pests and diseases. Some shelter insect pests at times when there are no other hosts. For example, greenhouse whitefly can overwinter on chickweed, ready to infect What is Crop Rotation?). Several virus diseases are also carried by weeds; one of the most troublesome is mosaic virus (see Garden Pests and Diseases of Cucurbits), which can affect groundsel and chickweed.and next year, so ensure that you remove this weed from the greenhouse and sheltered places nearby. Similarly, weeds in the brassica family such as shepherd’s purse can carry clubroot disease. Remove them promptly from the or they will reduce the value of (see
The presence of any weeds may also encourage fungal diseases by restricting the airflow round crops.
Another problem with weeds among fruit and vegetables is that they can cause difficulties in harvesting the crops. Something like a small annual nettle can make picking low-growing crops likeslow and uncomfortable. Weed seedlings mixed with cut-and-comeagain salads are not always easy to spot after they have been picked; whereas chickweed and bittercress are edible, groundsel and foxglove are poisonous.
Finally, weeds can look unsightly. In formal gardens, any weeds in beds, borders, paths, and even the vegetable plot are out of place.
In most gardens, however, weeds can have a place. If they are not threatening to compete with your plants or causing other problems, you do not have to get rid of them. Although you are not likely to tolerate any among your bedding plants, for example, there is no reason why they are not welcome along a hedge or next to the compost heap.
All weeds add diversity to the garden and some are positively beneficial, providing food for useful insects and even making attractive plants. A few are edible, adding flavour and interest to dishes in a similar way to garden. At the very least, when you do remove them, they make good compost material. Weeds can also help prevent erosion because their roots penetrate the soil strata and knit the layers together.
Weeds that encourage wildlife
Weeds of the Labiatae family such as red dead nettle (Lamium purpureum z 4) and ground ivy (Glechoma hederacea z 3) are good bee plants and small patches can look attractive among fruit bushes or along a hedge bottom. Bees also love theof clover (Trifolium spp. Z 3-7), and this plant has the added advantage that the bacteria associated with its roots add nitrogen to the soil so it actually feeds your lawn or fruit bushes. Hoverflies are attracted to
Umbellifers such as cow parsley (Anthriscus sylvestris z 7). Cow parsley can be left to flower in patches of long grass, along with, for example. Cut the grass down in mid-summer.
Ivy (Hedera helix z 5) is one of the best plants for wildlife. It provides dense cover and nectar, pollen and berries late in the season when other food is scarce. It can be left to climb up an old tree stump. The common nettle (Urtica dioica z 3) is valuable as a nursery plant for aphids, hence boosting the ladybird population (see Organic Gardening – Benefits of Garden Insects). Nettles also make a good liquid feed (see Liquid Feeds for Garden Plants). A nettle patch in the sun may attract red admiral and small tortoiseshell butterflies to lay their eggs.
Delicate annuals such as field poppies (Papaver rhoeas z 5), fumitory (Fumaria muralis z 5) and wild pansies (Viola tricolor z 4) can be very attractive. Leave a few seedlings in an informal border or vegetable plot. Ivy-leaved toadflax (Cymbalaria muralis z 3) grows in wall crevices, with drapes of small green leaves and pretty yellow and purple flowers. Leave it to colonize some areas of wall — it does no harm and is easy to pull out if necessary.
The leaves of the biennial weed garlic mustard (Alliaria petiolata z 3) add a mild garlic flavour to salads — leave a patch to reseed — and the leaves of short-lived annuals like chickweed (Stellaria media z 3), shepherd’s purse (Capsella bursa-pastoris z 7) and hairy bittercress (Cardamine hirsuta z 3) can also be used in salads. Young nettle leaves can be used in soup.