Our gardens will always have unwanted plants that alter the aesthetic as single specimens or that choke out desired plants. A weed could be an annual that won’t spread far or it could be an aggressive colonizer, which is why it’s important to identify weeds quickly.
Here are six reasons why you might have too many weeds, like this dandelion, and what you can do to prevent them.
A thickly planted garden leaves little room for weeds to establish.
Not enough plants. When you walk in a forest, woodland or natural lakeside environment, do you see different layers with lots of vegetation, or a few of the same plant dotted in the landscape? Likely, it’s the former. Nature desires rich layers and no fertile space left unfilled.
Let’s use more plants in our gardens. Ground-layer plants and matrix planting fill in the low gaps so that weed seedlings can’t get a foothold. Midlayer plants like taller grasses and thick flowering perennials shade the soil. Shrubs and trees of various sizes round out the design. Not only will these layers, working together, compete well against weeds, but they also will present a lush, attractive garden all year.
Using less wood mulch decreases ideal habitat for weed growth.
Too much mulch. Mulch can help regulate soil temperatures and compete with weeds, but mulch also tends to keep plants at a permanent establishment phase.
Plants love to touch and communicate, their roots and leaves sharing vital information and resources — not to mention working in concert to battle weeds. A swath of mulch is actually an inviting open space for weed invasion, because there’s nothing nature wants to do more than fill in the gaps.
Setting plants close together removes spaces for weeds to dig in.
Plants spaced too far apart. Throw away the plant tag that comes in the pot, and instead do online and book research. How does your newly acquired plant grow? Does it send out runners, self-sow, or is it a clumper? How fast does it grow? What size do others see it reaching — especially local folks with the same soil and climate?
It may just be that your plants need to be spaced closer together to prevent weeds from popping up. When I install new gardens, I often use plugs of something like shortbeak sedge (Carex brevior) as a ground cover matrix. At a minimum, I’ll space these plugs 12 inches apart, but 8 to 10 inches would be even better. They’ll fill in faster. I even do this spacing strategy with potted perennials, putting in milkweed, aster, nodding onion or Joe Pye weed at half the distance recommended.
Pulled weeds that leave ideal pockets for weed seeds. What happens when you yank a weed out of the soil? A lot of soil gets pulled up as well, creating a hole. This is essentially leaving lush conditions for a weed seed to germinate. If you’re fighting an annual weed, consider cutting down the plant so that it can’t flower and set seed. You won’t be disturbing the soil and creating a space for invasion. This method often works only for annual weeds that haven’t yet flowered. For perennial weeds, you’ll need to consider deep digging.
If gardens are matched to local climate and site conditions, the way this native garden in Los Angeles is, extra resources that weeds love won’t be needed.
Too much water and fertilizer. If you’ve chosen plants suited to your site conditions, you won’t need extra watering or fertilizer — the TLC that weeds absolutely love. There’s no need to overstimulate your beds if your garden plants are already thriving. Tilling can also stimulate weed growth, as it brings up buried weed seeds and helps create conditions conducive to germination.
Landscape cloth. This barrier fabric doesn’t always work to prevent weed establishment. Many weeds have tough roots that punch through it or grow laterally to find a gap. Wind blows in soil particles and creates a thin layer above the fabric for germination no matter the mulch depth. The weed barrier also prevents nutrients, oxygen and water from cycling between the soil and the world above — plant roots need to breathe too. Finally, landscape cloth is just a pain in the neck when you want to add new plants.