Q: I am prone to weed outbreaks in my vegetable beds. What options do I have to limit such invasions in the future?
A: I sometimes find hand weeding therapeutic, but yes, it can sore your muscles and test your patience. As with many gardening challenges, prevention is key.
First, keep the soil covered as continuously as possible. Just like the vegetable seeds we sow, weed germination needs good soil contact. Deny them that, and few will successfully colonize the bed after blowing into it. In season, the soil between developing plants can be covered with either inorganic or organic mulch. (Sustainable options include biodegradable weed barrier paper, straw, wood chip mulch, etc.)
You can also try a “mulch” of live ground cover, either decorative or edible. While any plants growing near your crops can compete with them for moisture and nutrients, the benefits they offer in providing habitat for natural enemies, attracting pollinators, and protecting soil health can outweigh any downsides, especially when they will save you time tending to the garden.
You can also use cover crops while a bed is idle. There are several candidates and the choice depends on when you need to sow them and what additional benefits you want them to provide – nitrogen fixation, pollinator resources, ease of removal, etc. You can learn more about options on our cover crops page.
Although a little soil disturbance is inevitable when planting and removing crops, minimize any other disturbance as this will bring buried weed seeds to the surface where they can germinate.
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The second priority is to prevent weeds that you cannot remove immediately from getting to seed. If you spot a flower stalk or a developing seed head, cut it off. Perennial weeds can regenerate from established roots. So if your time is limited, focus on removing them and not on annual weeds that will die off on their own within a year of emerging.
Herbicides should be the last resort as they can have unintended consequences on the environment or damage desirable crops. However, there are other approaches, which we discuss in detail on our chemical-free weed control page. The focus is on ornamental gardening, but many of the techniques can be adapted for edible plantings as well.
Q: How can I tell if a deciduous shrub is dormant or dead?
A: It’s still a bit early for most deciduous trees to sprout leaves, so chances are they were healthy last fall. If you don’t want to wait for new growth to appear, which makes dieback more obvious, the “scratch test” is an easy way to check.
The cambium is the living layer that lies just below the bark. Specialized tissues supply water and nutrients to buds, flowers, and leaves, or transport the sugars produced in the leaves to various other growth points or storage areas in the plant. You can think of the cambium as the circulatory system of a plant, and in fact it is similarly referred to as the vascular system of a plant. This means that the death of cambium will result in the death of all growth that has nurtured it above or beyond that point. Similarly, root loss (e.g., from infection, injury, or lack of oxygen) can cause cambium dieback in branches, leading to dieback. Where cambium remains alive compared to where it died can help you determine what was the root cause or where to look for ongoing damage.
Living cambium is what the scratch test is looking for. You will injure a plant slightly to perform this test, but healthy plants will not be unduly stressed. Slice or peel the bark lightly in 1/4 to 1/2 inch strips running the length of the stem. Green moist cambium alive; dry, brown, or gray cambium is dead. White tissue can be difficult to assess, as it sometimes means you’re cutting too deeply into the underlying layer of wood. Start with the youngest upper growth and if you find dieback, try down to the lower, older wood until you find living cambium. This will show you which dead growth can be removed. In the worst case, shrubs whose branches have all died could grow back from their roots, but usually such thoroughly damaged plants just need to be replaced.
The University of Maryland Extension Home and Garden Information Center provides free garden and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.