July 11, 2015

1 - Removing weeds from your garden using cultural or chemical weed management practices.

Yard and Garden July 11, 2015


Weeds!!! I have more weeds in my garden than I can remember ever having before. I guess it is because this year we had so much early rain. Can you give me any advice to make help me get rid of the weeds more easily? I prefer to not use chemicals.


Getting rid of weeds is not a realistic prospect, managing them to minimize their negative impacts can be done. In managing weeds, persistence is a critical weapon in your arsenal. Weeds quickly get out of hand if you do not deal with weeds on a regular basis, whether your approach is to use cultural or chemical weed management practices. The moisture that some of New Mexico had during May and June has resulted in earlier and more abundant growth of weeds.

Cultural weed management practices include a number of things. Irrigation methods that localize moisture will help reduce weed growth during periods between rains. Mulch can also help reduce weeds and make them easier to remove. Use of low-growing, spreading groundcover plants can serve as living mulch with the same effect. Frequent removal of weeds manually is also important.

Irrigation by drip irrigation, olla irrigation, or other means that directs water to limited areas where it most benefits desired plants conserves water and weakens weeds that try to grow elsewhere on rain water alone. Without supplemental water, weeds will grow more slowly and give you more time to remove them. It is easier to remove weeds from most soil, so whenever possible remove these weeds soon after a rain. In areas of irrigation, frequent weed management will be necessary.

In areas away from irrigation a scuffle hoe is a useful tool. A scuffle hoe is one that cuts weeds just at or just below the soil line. In the case of annual weeds this removes the weed and by minimizing soil disturbance reduces new weed seed germination. If the weeds are perennial weeds they will grow back from their roots, but frequent cutting with the scuffle hoe will weaken the weeds to the point that they grow back very slowly or not at all. Chopping the soil with a traditional hoe or digging with a shovel disturbs the soil and brings new weed seeds to the surface where they can germinate. Weed seeds buried deeply in the soil may remain alive for many years, but do not grow until they are near the surface and receive sunlight.

Mulch helps reduce weeds by reducing the light at the surface of the soil and inhibiting weed seed germination. Perennial weeds may come through the mulch, but because the mulch conserves moisture in the soil, the mulch can make it easier to pull the weeds. Some scuffle hoes can work through a layer of mulch and may be employed to remove weeds growing in mulch. The choice of organic mulch (wood chips, straw, or bark) or inorganic mulch (crusher fines, gravel, cobbles, and such) depends on the plants in the landscape and garden. Some can tolerate the heat that inorganic mulch accumulates, but others need the organic mulches that do not generate as much heat from our plentiful New Mexico summer sunshine.

Understanding which weeds you have growing in your garden and landscape is important in managing the weeds. I referred to annual and perennial weeds and mentioned some of their characteristics. The annual weeds (puncture vine/goatheads, pig weed, purslane, mustard weeds, spurge, some grasses, and many others) must grow from seeds each year. Some germinate in the fall and survive the winter, some germinate in late winter, and some do not begin growing until the soil warms in late spring. If you prevent them from forming seeds you can reduce the potential weed problems for the next year. However, since weeds seeds can persist in the soil many years before germinating, they will continue to reappear, but you can begin to reduce their presence by your persistence. Perennial weeds (silverleaf nightshade, globe mallow, bindweed, and others) grow from seeds as well, but they also are able to regrow from buds on their root systems. Pulling newly germinated perennial weeds before they can establish their perennial root system helps reduce the problem. As they regrow from established root systems, frequent removal of the tops will help diminish the food reserves in the roots and weaken the weeds over time. As they become weaker, they become easier to manage.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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