When fighting weeds, only persistence pays off

May. 25, 2013 @ 09:08 PM


No landscape is complete without flowerbeds. Whether you prefer annuals, perennials or a mixture, I can guarantee you of one thing: you will have weeds! While there is no quick and easy solution to weed management, there are several strategies that will help.

If at all possible, start with a clean bed. If your beds were neglected over the winter, that will mean spending some time pulling weeds by hand.

Next, you may want to apply a pre-emergent herbicide. These are usually granular products that are sprinkled on the ground around the plants. Most will need to be watered in (with irrigation or rainfall) shortly after application. They are safe to use on a variety of flowers, but check the list on the product label to be sure.

Note that these pre-emergent herbicides control only a few weed species, so you won’t eliminate all weed problems. Also note that these products work by killing weeds as they germinate, i.e. they have no effect on weeds already growing

Once the pre-emergent herbicide has been applied (or even if you skip that step), it is wise to put down a two or three inch layer of mulch. If you are adding to an existing layer of mulch, add just enough to bring the total depth up to three inches. Again, this will help to prevent weeds from growing.

Note that none of the practices mentioned so far will control weeds that spread by vegetative means (e.g. tubers, bulbs or underground stems). A great example is bermudagrass (a.k.a. wiregrass), which can invade underground from nearby areas.

Another example is nutsedge, which has an underground tuber that can send a shoot through a thick layer of mulch. I’ve even seen it poke through the plastic bed covers used by commercial strawberry growers!

So how do you control those weeds that evade methods mentioned above? In the case of grass weeds such as crabgrass and bermudagrass, you may be able to use a spray containing fluazifop or sethoxydim (take your reading glasses to the store, you have to read the fine print!).  As above, check the product label to make sure it’s safe to use on the flower species in your garden.

However, in the case of nutsedge or broadleaf weeds, such as clover and henbit and dandelions, any spray that will kill the weeds will also kill your flowers. That leaves handweeding and “directed-sprays” as your only options.

A “directed-spray,” as the name implies, is the application of a liquid herbicide in such a way that it contacts only the weed foliage. You can use a product containing diquat, glyphosate, glufosinate or even the herbicidal soaps. Any of these will kill your pretty flowers as quickly as the weeds. A trigger style spray bottle set to a coarse spray makes it easier to target the weeds. You can also try shielding your flowers with a sheet of cardboard, or even cutting the bottom out of a two-liter soda bottle, placing it over a weed, and spraying through the top.

The most important thing to remember is to be persistent. Spending five minutes each week weeding each bed will help you stay ahead of the game. Oh, and read the instructions on the product label.

Seriously, read the instructions.