Robin Gale-Baker, from Sustainable Macleod tells you why you should weed. This is one of a series of articles she has written about growing techniques (see right hand sidebar). She has also written a number of articles about growing vegetables and fruit trees.
To weed or not to weed – that is the question!
Weeding is often seen as an aesthetic consideration where weeders prefer the order of a tidy garden while non-weeders prefer the unruliness of a wild garden. However, this is a minor consideration compared with less-than-happy role that weeds play in a healthy edible garden.
Weeds are, by their nature, tougher than most vegetables and easily able to not only compete with them but also to dominate. Just think of an untended veggie bed – is it the weeds or the crops that tend to dominate?
There are 5 main reasons to weed to protect your veggie garden:
- Retention of moisture in the soil.
- Retention of nutrients.
- Adequate sunlight.
- Good air circulation.
- Disease control.
Watering of edible plants is essential. Both annuals and perennials thrive when well watered. Under-watering is one of the main contributors to crop failure or poor results so sharing this precious and expensive resource with weeds is problematic.
Weeds suck the nutrients out of our soil at a high rate, competing favourably with our veggies. Do we really want to be feeding our weeds at the expense of our veggies?
How often have we uncovered a pale and unhealthy specimen that we have planted as we weeded or how often have un-thinned vegetables created the same result? Sunlight is an essential ingredient for healthy produce and space around our plants is needed to achieve this.
Weeds smother other plants by growing close to them and, by so doing, deprive them of adequate air circulation and create the perfect environment for the development of fungal diseases. We prune fruit trees for the very purpose of letting in air (and light), and preventing fungal attack but often don’t apply the same principle to our veggies.
Many weeds play host to damaging viral diseases which can be transmitted to our veggies by insects which are in turn harboured by these weeds. For example, lettuces can suffer from ‘necrotic yellow virus’ which turns them yellow and this is transmitted by aphids from the common milk thistle and sow thistle; diseases of the Solanaceae family (which includes potatoes, tomatoes, eggplants and capsicums) are transmitted by aphids from deadly nightshade weeds such as Datura (Jimson weed). Other common weeds include little mallow, mouse-ear hawkweed, common cats-ear (false dandelion) and lamb’s quarter. Be aware that these weeds may not look like they are infected when they are actually infected. Common insects which transmit viruses include aphids, greenhouse whitefly (not other whitefly species) and thrip. Common viruses spread by aphids include cucumber mosaic virus, tomato spotted wilt virus, watermelon mosaic virus, zucchini yellow mosaic virus, papaya ring-spot virus. Greenhouse whitefly affects cucumbers and beetroot, whilst thrip affects tomatoes and capsicums.
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The veggie gardener needs to deal with both annual and perennial weeds. Annual weeds produce seed which is spread predominantly by wind while perennial ones generally spread by rhizome (root). Weeds that spread through rhizomes include flat weeds like dandelion, cats-ear and hawkweed. There is an occasional weed like dock that disseminates in both ways.
It is best to remove annual weeds before they produce seed heads. This should begin in August and continue until done.
Perennial weeds generally are slower to spread and not as urgent.
A significant area in the vicinity of your veggie garden needs to be weed free, not just the beds themselves. It is important also to weed around greenhouses to reduce weed sources that insects may feed on, introducing viruses into polytunnels and greenhouses.
To summarise: weeds have their place but that is in the wild – not in suburban gardens!