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Garden Q&A: How to reduce weeds in the vegetable garden

Q: I tend to get weed outbreaks in my vegetable beds. What are my options for limiting such invasions in the future?

A: Sometimes I find hand-weeding therapeutic, but yeah, it can make your muscles sore and test your patience. As with many of gardening’s challenges, prevention is key.

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First, keep the soil covered as continuously as possible. Just like the veggie seeds we sow, weed germination needs good soil contact. Deny them that, and few will successfully colonize the bed after they blow in. In-season, soil between developing crops can be covered with either inorganic or organic mulch. (Sustainable options include biodegradable weed-barrier paper, straw, wood chip mulch, etc.)

You could also try a “mulch” of live ground covers, either decorative or edible. While any plants growing close to your crops can compete with them for moisture and nutrients, the benefits they provide of adding habitat for natural enemies, attracting pollinators, and protecting soil health may outweigh any detriment, especially if they save you time maintaining the garden.

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You can also use cover crops while a bed is fallow. There are several candidates, and choices depend on when you’d need to sow them and what additional benefits you’d like them to provide – nitrogen fixing, pollinator resources, ease of removal, etc. You can learn more about options on our Cover Crops page.

Although a bit of soil disturbance is inevitable when planting and removing crops, minimize any other disturbance because this brings buried weed seeds to the surface where they can germinate.

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The second priority is to prevent any weeds you cannot promptly remove from going to seed. If you spot a flower stalk or developing seed head, cut it off. Perennial weeds can regenerate from established roots, so when your time is limited, focus on their removal over any annual weeds, which will die on their own within a year of appearing.

Herbicides should be a last resort since they can have unintended consequences for the environment or can injure desirable plants. There are other approaches, however, which we discuss in detail on our page Manage Weeds Without Chemicals. Its focus is ornamental gardening, but many of the techniques can also be adapted to edible plantings.

Q: How can I tell if a deciduous shrub is dormant or dead?

A: It’s a bit early for most deciduous shrubs to be leafing-out just yet, so odds are they’re fine if they were healthy last autumn. If you don’t want to wait for new growth to appear, which will make dieback more obvious, an easy way to check is the “scratch test.”

Cambium is the living layer that lies just underneath the bark. Specialized tissues supply buds, flowers, and foliage with water and nutrients, or carry sugars produced in the leaves to various other growth points or to storage areas in the plant. You can think of cambium somewhat like a plant’s circulatory system, and in fact it’s similarly referred to as a plant’s vascular system. This means that the death of cambium will result in the dieback of all of the growth it fed above or beyond that point. Similarly, root loss (such as from infection, injury, or oxygen deprivation) can cause the death of cambium in branches, resulting in dieback. Where cambium remains alive compared to where it died can help you determine what the primary cause was or where to look for ongoing damage.

Living cambium is what the scratch test looks for. You are wounding a plant slightly to perform this check, but healthy plants won’t be unduly stressed. Nick or lightly peel off the bark in a quarter- to half-inch long strip along the length of the stem. Green, moist cambium is alive; dry, brown or gray cambium is dead. White tissue can be difficult to judge, since it sometimes means you cut too deeply into the wood layer below. Start on the youngest upper growth and if you find dieback, keep sampling your way down to lower, older wood until you find living cambium. This shows you what dead growth can be removed. Worst case, shrubs that had all of their branches die might resprout from their roots, but usually such thoroughly damaged plants just need to be replaced.

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University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.


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