What is a weed?
A weed is a plant where you don’t want it. What might be a lovely wildflower to some people in some places, may just be a weed to others. Rosebay Willow herb (Chamerion angustifolium), for instance can be beautiful in the right place, and wild garlic (Allium ursinum) has lovely flowers and is edible (only eat leaves and flowers if harvesting from the wild), but can spread and take over. Grass is an example of a plant we grow in abundance, but can be a real nuisance if it gets into a flowerbed. I love wild poppies, but I don’t like yellow poppies growing in the lavender hedge. Ivy in the right place provides valuable habitat and food for wildlife, but you may not want it growing up vulnerable trees.
So, why do we not want weeds in our gardens?
Our plants need nutrients from the soil, water and sunlight in order to thrive. Weeds compete with our plants for these essentials. What we consider weeds tend to be plants that are very good at outcompeting other plants, very good at reproducing themselves, or spreading vegetatively and colonizing an area and sometimes, as is the case with ephemeral weeds, can flower and set seed several times in one season.
The following is a guide to some of these common weeds.
Ground elder (Aegopodium podagraria)
Being fortunate enough to live in an area where there is no Japanese Knotweed, my biggest problem weed is ground elder. It is said to have been introduced by the Romans for medicinal purposes, and it can be eaten, when the leaves are young and tender. It is high in vitamin C and also has very attractive umbelliferous (cowparsley-like) white flowers. However it spreads rapidly by white underground roots and rhizomes and quickly outcompetes other plants. Once you have it in your garden you are unlikely ever to get rid of it. You just have to keep digging it up and digging it up and digging it up again, which is particularly difficult as its roots get entangled with the roots of all your other plants including shrubs and trees that you can’t disturb. Alternatively, you can mulch over it with black plastic and leave it for at least two years, or put the area it’s in down to grass and keep mowing it.
Nettles (Urtica dioica)
There are various types of nettle. The white and red dead nettles (Lamium album and Lamium purpureum) so called because they don’t sting, are actually part of the mint family and a different family to stinging nettle. Some people welcome these in the garden as ground cover in shade – the bees certainly like them. There is also an annual stinging nettle (Urtica urens) which is smaller than the perennial version and has a less powerful sting, and a stingless nettle (Urtica galeopsifoila). But the one we worry about most is the perennial stinging nettle, which has quite pointed and jagged leaves and insignificant greenish flowers (male and female on different plants) and delivers a nasty sting if you are unlucky enough to brush up against it. It is often found particularly on rich ground. Its roots are yellow and not too difficult to dig up. If you have a space you can allow it to grow, it is valuable for wildlife supporting between 40 and 100 different species. It provides food for many caterpillars, including those of the Peacock, Red Admiral and Small Tortoiseshell butterflies. The caterpillars in turn attract birds, including sparrows. Ladybirds sometimes lay their eggs on nettles as they attract early aphids, food for ladybird larvae as well as birds, and the nettle seeds are eaten by bullfinches and siskins. The leaves also make very good compost and can be used to make a liquid plant food. The young leaves can be eaten, but from early to late summer they can accumulate gritty particles which are bad for the kidneys and urinary tract.
Field Bindweed (Convolvulus arvensis) and Hedge Bindweed (Calystegia (Convolvulus) sepium)
Both these types of bindweed can cause a problem. They spread by white underground stems (rhizomes) and roots, which are brittle so difficult to dig out without breaking, and each little bit left in the soil can grow into a new plant. Hedge bindweed is a climber, twisting its stems around other plants and competing for light as well as soil nutrients. Once it has done this it is very difficult to pull down without damaging the host plant, so it’s important to recognize its shoots in spring and keep on top of it early, or dig an area over thoroughly before planting your plants.
Herb Bennet (Geum urbanum)
This wild geum is very common around Oxfordshire, Banbury area – it likes woodlands and damp shady places. It is edible – you can steam or boil the young leaves and use the roots in replace of cloves in recipes. It is not too difficult to dig up with a hand fork, as it has fibrous roots, but do be careful not to dig up any wanted Geums with very similar leaves.
Dandelions (Taraxum officinale)
Dandelions have long tap roots, so you need to dig deep with a spade, fork or dandelion weeder and try to get all of the root out, otherwise it will regrow. It can quickly spread by seed and has very distinctive and attractive fluffy seedheads, often called ‘dandelion clocks’. If it weren’t so common, it would be sought after for its beauty. The roots can be ground to make ‘dandelion coffee’ and the young leaves can be eaten in salads.
Enchanter’s Nightshade (Circaea lutetiana)
Enchanter’s nightshade is a common, but pretty wild flower which can become a weed – I have seen it take over beds. It is difficult to get rid of as it has two methods of spreading – by white underground rhizomes, and by seed. The seeds have small hooks on which means they attach themselves to your clothes and to animal fur, and spread that way, and the roots, though not deep, break easily so are difficult to get rid of. Keep digging it up with a hand fork and try not to let it go to seed, and if you can’t get rid of it, console yourself with the thought that it is rather attractive anyway.
Speedwell (Veronica agrestis)
Speedwell seeds seem to germinate at lower temperatures than anything else in the garden. I have been known to weed out fresh seedlings in January. Although a small plant, it can spread prolifically, getting inbetween all your garden plants. The common speedwell (or ‘green field speedwell’) has very small flowers, but the less common birds-eye speedwell (Veronica persica) has slightly larger very attractive flowers, which I would welcome into the garden. Hoe common speedwell, or handweed.
Dock (Rumex spp.)
Dock has very long tap roots, so is quite difficult to dig out, and will regenerate from the first 15cm of root. It also seeds prolifically, so cut down before it sets seed and dig out, or cover with black plastic for 2 – 3 years.
Couch Grass (Elymus (Agropyron) repens)
Couch grass spreads through underground runners called rhizomes. The rhizome tips are sharp so can grow through potatoes and bulbs. Hoeing helps reduce it but you need to dig out the rhizomes and roots with a hand fork to get rid of it.
Hairy Bittercress (Cardamine hirsuta)
Hairy Bittercress is a small weed which often gets into potted plants and overwinters well on bare soil. It is not too much trouble to hoe off or hand weed and can be eaten; it has a peppery flavour and is best eaten before it flowers.
Buttercup (Ranunculus repens)
The buttercup which causes the most nuisance is creeping buttercup, which spreads by runners (or stolons) and is most common on moist ground and in lawns. It also seeds so can be very prolific, although it has relatively shallow fibrous roots so is not difficult to dig out with a hand fork.
Bramble/ Blackberry (Rubus fruticosus)
If you have space for a wild, thorny blackberry the delicious fruits can be better than cultivated ones, and if you don’t pick them yourself they will be food for birds and other wildlife. The leaves are a source of food for caterpillars and the flowers attract bees and butterflies. However, if you don’t want them, they can be difficult to get rid of, or contain, especially as the stems will grow in an arch and root themselves at the end, making a new plant and spreading, and the tough roots are difficult to dig out.
Fat Hen (Chenopodium album)
Fat hen is most commonly found on agricultural land, or allotments and vegetable gardens – it likes recently exposed ground in sunny sites. The best way to get rid of it is by handweeding or hoeing. The young leaves (which don’t smell if you rub them) and greyish-green flowerheads are edible and rich in vitamin A and C, but if it has been growing in manure, don’t eat too much of it as it may contain too much nitrogen and give you a stomach ache, and be very careful not to confuse it with the deadly poisonous henbane (Hyoscyamus niger), which has yellow purple-veined flowers, is fetid-smelling in summer and has hairs on its leaves and stems which make it feel sticky.
Goosegrass/ cleavers (Galium aparine)
Goosegrass is a fun weed if you are a child – the stems and seeds stick to your clothes and animal fur so it can spread prolifically. To keep on top of it just pull up and dispose of stems. If you want to, you can eat the young stems before they set seed and get tough – sauté them in butter or put in soups or omelettes.
Garlic Mustard/ Jack-by-the-hedge (Alliaria petiolata)
Garlic mustard is an edible biennial weed, which means it produces heart leaf in the first year and flowers and sets seed in the second year. It has a long white tap root and a strong taste of mustard and garlic. If you don’t want it, dig it out.
For more information about edible garden weeds see Alys Fowler’s wonderful book ‘The Thrifty Forager’ published by Kyle Books.