Fall has barely started, but spring weeds are already growing. Now through spring is the best time to kill them. Cheat, foxtail, heron’s bill, groundsel, bitter cress, cleavers and many others can most easily be killed in the months before they start blooming. The earlier you get to them, the easier it is.
Heron's Bill, starting to bloom in the spring. It takes a lot of mulch to smother it at this point.
You can kill them three ways: by smothering with mulch, preferably leaves; by pulling them out; or by cutting them below the crown, the point from which roots and leaves grow.
Smothering with mulch saves you the most work in the long run, in the places where you can mulch. Leaves, when spread 2” or more deep, can stop weeds that haven’t even started yet and those too small or too crowded to be worth individual attention. Tiny seedlings can grow through a few layers of light fluffy weeds, but more than that can make them run out of food before they find the light. Blocking sunlight on soil can stop seeds that need sun on soil from sprouting at all. And leaves make a lousy seed bed for seeds that fall on top of them because they dry out quickly.
Leaves covered with pine needles, which hold them in place.
But not all leaves are created equal. Some are eaten by worms before fall is even over, some by spring, some stick around until midsummer, and some have to lie around decomposing for a year before even crazy snake worms will touch them. (If you have no soil life because fine bark has killed it all, it may take a year or more for even soft leaves to go away, but that’s a subject for another column.)
Fallen red maple leaves stopping groundsel and other weeds
Hard leaves, like oak, sycamore, sweet gum and magnolia, tend to be stiff and fluffy and take a few more layers to stop weeds from growing through. Many medium and soft leaves lie flat and can stop weeds from sprouting with only a single layer, but will be gone before summer weed seeds start flying. A mix of hard and soft leaves 2 inches or more deep will stop most small seeds and plants from growing, and feed and soften the soil to easily pull the ones that get through. 2 inches of leaves in the fall is enough to keep flowers and shrubs fed and happy, with loose, easy-to-weed soil that is protected from rain and sun.
A foot or more of leaves will grow big vegetables as they decompose. For small seeds, spread an inch of compost on top and plant on it. Large seeds and starts can be planted into the leaves without compost, allowing the leaves to stop weeds from sprouting on top.
Cheat, blooming en masse, at the point when the roots are shrinking and it is again fairly easy to pull.
Annual grasses, large and small, are most easily pulled from 3 to 6 inches tall. The longer they grow, the more roots they hold the soil with and the harder they are to pull. Annuals cheat and foxtail are a lighter green and have a softer texture than perennial grasses, are often fuzzy, and grow in clumps, without runner roots. As they send up seed stalks in the spring, they use up their roots and are more easily pulled, but time is then short to pull them all.
Most taproots are more easily pulled when the ground is wet, but some in rocky or very hard soil, or with soft stems, won’t pull and must be cut under the crowns. This will stop most annual weeds and many perennials, but some perennial taproots, like dandelion, dock, and creeping oxalis, need the soil to be loosened with a tool and pulled eventually. Some, like oriental poppies, can grow back from a root tip deep in the soil and take several years to get rid of completely.
Rycke Brown, Natural Gardener 541-955-9040 firstname.lastname@example.org