Post category: Weeds
Vegetable area and flower beds or borders
Cultivated areas, such as the vegetable area and flower beds, should first be made weed-free by removing perennial weeds while digging, or by using Resolva or Roundup in early summer, if the ground has been neglected.
Early digging in the vegetable area buries weeds before seed formation. Cultivated soil may be kept free of weeds before the vegetables or flowers are sown or planted, by hoeing, or spraying with Weedol, when the weeds are still small. Where vegetables or flowers have been sown or planted, only hoeing and hand-weeding may be used.
Established shrub borders, rose beds and fruit plantations
New planting should be treated as above, for a year or two. After that, hoeing and Weedol may be used to dispose of annual weeds. Tumbleweed, Roundup or Brushwood Killer may be used to carefully ‘spot-treat’ perennial weeds.
Paths, driveways, patios
Where there are no plants that might be damaged, chemical weed killers and preventers are ideal. It is often difficult to hoe or handweed in these situations because weeds have their roots between slabs or cracks in concrete. Specially formulated mixtures of weed-killing and weed-preventing chemicals are sold for use on these areas.
These are used as a single dose solution to both existing weeds and germinating weed seeds and are applied in spring or early summer, such as Pathclear.
Moss and algae can be killed on paths, walls or tarmac by spraying with Mosgo or mosskillers. Sweeping paths and drives to prevent debris building up helps to prevent moss and algae. If tree seedlings, brambles or briars need to be killed, use Brushwood Killer. Asulox will kill bracken.
Chemical weedkillers work by destroying the foliage, or by poisoning the weed plant’s internal system. Weedol, Gramoxone and Basta destroy the foliage, the green top of the plant. If the weeds sprayed are annuals without storage roots, they die. Perennial weeds survive Weedol, Gramoxone and Basta in the same way as they survive hoeing.
Deep-rooted japanese knotweed is difficult to kill without chemicals .
Tumbleweed, Roundup and Brushwood Killer work by poisoning the weed’s internal system, which means they have the ability to kill perennial weeds. These chemicals are taken in by the foliage and then passed right down into the storage root system. This makes them more effective than digging for the disposal of perennial weeds.
These translocated weedkillers are very specific though in the way they work, and in what they kill. Roundup kills both grasses and broadleaved weeds. It needs six hours without rain, after application. Brushwood Killer kills broadleaved weeds only and growth must be active. Repeat applications may be necessary. Read the instructions carefully.
There are several chemicals that may be used to stop weed seeds from germinating. These are called residual weedkillers and are used in combination with the contact weedkillers to control weeds on paved areas.
The application of a layer of material free from weeds or weed seeds is very effective in preventing weeds. Weed seeds germinate but die because they lack adequate light. Loose mulches, such as compost, manure, bark, grass clippings, peat or gravel must be thick enough to block out light.
These only work when applied to weed-free soil, and in the case of manure and compost must be well-rotted and weed-free themselves. Organic mulches have to be topped up every couple of years, because they break down, themselves providing excellent rooting conditions for blown-in weeds.
Gravel must be kept free of fallen leaves, for the same reason. Thick black polythene is an excellent mulch, and may even be used to kill existing weeds, but it tends to split and break up after a few years. A combination of polythene and gravel is long-lasting, the gravel shielding the polythene from the sun. But weed seeds can begin to grow in the gravel.
Weed-preventing fabrics are better than polythene for this purpose because they allow water to pass through to the soil beneath. Plant debris, that would build up and provide rooting material for weeds, is more likely to rot down and pass through to the soil beneath.
Old carpet, or thick layers of newspaper or cardboard, can be used as light-excluding mulches to achieve weed control. These do not last very long but can be very effective while they last.
Pulling up weeds by hand from among garden plants is the oldest and surest way of separating out the unwanted. Weeding by hand is very effective, but slow, and suitable only in close to plants where hoeing might cause damage. An old kitchen knife is a useful aid to hand-weeding.
Shake the soil off the roots of weeds after pulling them up and collect them in a heap or a weeding bucket as the work is carried out. This approach prevents the weeds rooting again, as many weeds are capable of doing.
Hoeing is a quick, effective, safe and cheap way of controlling weeds, with little or no damage to crop plants. Hoeing must be done while the weeds are small. The ideal stage is when they have one or two ‘true’ leaves, and are just a couple of centimetres high. The hoe separates the top from the root, and the weed seedling dies.
Hoeing too early might only move the seedlings about, because the root may not be deep enough to be caught by the hoe. Hoeing at the right stage will kill perennial weed seedlings before they get a chance to develop their storage root survival system. Hoe on a warm, bree day, so that the weeds dry out before they get a chance to root again.
Perennial weeds that have developed their storage roots will not be controlled by hoeing – they simply grow new leaves. Instead, they must be dug out. Use a fork or spade, and make sure to get the entire storage root system. Leave the lifted weeds on a hard surface to die.
A weed is a plant in the wrong place – grass is okay in a lawn, but not in the flower bed alongside. Weeds compete with garden plants for space, light, water and nutrients.
Young seedlings of fat hen weed
Annual weeds are wild plants with a remarkable ability to produce seed quickly and in large quantities. They grow fast, reach flowering size in a matter of weeks and shed seed – each new generation spanning as little as eight or ten weeks.
Under natural conditions, the annual weeds exploit temporary disturbance of the soil and in the garden, they are weeds of cultivated ground, taking advantage of the soil being broken up for crop plants.
It is essential to prevent them getting big enough to produce seed. They have no other means of survival or spread, so the cycle is easily broken. There is a reservoir of weed seed in the soil, which is added to each season.
If seed production is prevented, the reservoir declines as the weed seeds get older and lose their ability to germinate. There is a lot of truth in the saying – ‘one year’s seeding is seven years weeding’. Common annual weeds include groundsel, shepherd’s purse, chickweed, annual meadow grass and speedwell.
The perennial weeds are persistent weeds that, once established, spread until they take over the available ground space. They survive over winter by dying back to a network of thick, fleshy storage roots, or a tight rosette of leaves. Each year the storage root network becomes more extensive, and this is the main method by which these weeds spread.
Broadleaved dock – a troublesome weed
They may be controlled by removing the root system completely, or by killing it with weedkiller. Removal is difficult, since even small pieces of root may be enough for the weed to regenerate. Ground made free of perennial weeds is reasonably easy to keep clear.
Hoeing will prevent establishment from seed, and if the root ball of every new plant is checked for the presence of perennial weed roots, there is no way they can get in.
Perennial weeds infest both cultivated and uncultivated ground. They prefer less actively cultivated ground, such as a shrub border, where their root systems will not be disrupted so much.
Only a few, such as bindweed and scutch, are vigorous enough to tolerate continuous disturbance. Other common perennial weeds include nettles, docks, bishop weed, creeping thistle and dandelion. Many lawn weeds are perennials too, principally within lawn areas but also occur in flower beds, especially dandelion, clover, buttercup and daisies.
Living plants act in the same way as mulches to prevent weeds – by blocking access to light. Any low-growing, spreading plant, either woody or herbaceous, can be used, some being better than others. A few weeds will always appear through gaps – especially in the early years. On occasion, the ground cover itself may become a nuisance.
Lots of plants – no room for weeds
Commonly used ground cover plants include hardy geranium, St John’s wort, vinca, ivy, ajuga, lamium, acaena and bergenia. But any plant that spreads to cover the ground with foliage can be considered as ground cover and this means most perennial flowers and shrubs.
The principle is to cover the soil with desirable plants to deny weeds the space, moisture, light and nutrients they need. If garden plants are well planted and cared for until they are established, they will compete strongly with weeds, and greatly reduce the effort of weeding.