The rule is simple: apply pre-emergent garden weed preventers in early spring. This is true. It's also a myth. Because of it, trillions of unwanted weeds invade American garden beds every year. Early spring may be the optimal time to begin a pre-emergent weed prevention routine, but it's not the only time. Actually, it's never too late to begin.
The spring-only myth probably took root, so to speak, with lawn care advice. To prevent crabgrass, a lawn scourge and an early sprouter, it's important to apply pre-emergent crabgrass preventer in early spring. A common lawn care tip is to apply it about the time the forsythia bud up. That's true for the garden too. But these early spring sprouters are only some of the weeds gardeners face. Weeds are often more of a problem in the garden than they are in the lawn.
In turf, emerging weeds must compete with the tightly packed grass plants of the turf itself. Grass that's mowed high, and is well watered and fed, is itself a barrier against many weeds.
Garden soil, on the other hand, is naked and defenseless by comparison. Even a crowded garden is vulnerable. Garden soil harbors millions of dormant weed seeds, ready to sprout when exposed to light. They are aided and abetted in this pursuit by gardeners themselves. Every time a new plant is planted – or, worse, when weeds are aggressively pulled – the soil is turned and weed seeds come to the surface.
Different types of weeds set seeds at different times. So more seeds enter the garden every day, carried by wind, birds or animals. In spring, summer and fall, mature weeds are weed factories producing millions of seeds. A single mature lambsquarter weed can produce up to 70,000 seeds. Common purslane produces seeds from spring through frost, with a single plant capable of producing as many as 240,000 seeds! This is why each weed prevented exponentially decreases the number of future weeds that need to be pulled.
Mulch is highly effective in the war against garden weeds. It denies weed seeds the light they need to sprout. Combining mulch with a pre-emergent weed preventer such as Preen provides a one-two weed prevention punch that helps stop weed seeds in garden soil (and in the mulch itself) from rooting for three to six months, depending on the product. Corn gluten is an organic weed preventer and is often used in vegetable gardens.
Mulch and pre-emergents aren't weed killers. They're weed preventers. By stopping seeds from sprouting, they stop weeds before they start. To learn more about weeds and weed prevention, visit www.preen.com.