Archive for August, 2009

Weedy Lawns

Saturday, August 29th, 2009


Coming Back to Weeds

It has been one of the coolest, wettest summers on record and the weeds are loving it! By the end of July, we all had clover and dandelions all over our lawns. This month, crabgrass is making a comeback along with sedge and plantains.

Before chemical weed control and fertilization, clover was considered desirable because it fixes nitrogen in the soil (which is good for grass) and generally has a symbiotic relationship with grass. In fact, folks used to buy grass seed mixes with clover seed mixed in on purpose (gasp). Unless it’s a particularly wet year, clover won’t outrun your grass and even then, if you let the grass get tall in the heat of summer, that will allow the grass to keep the clover to at bay.

Crab grass is easily controlled with proper watering. Crab grass likes light daily water, fescues and Kentucky blue grass like heavy water every three days. Control the water and you master the crab grass. Plantains prefer compacted soil that is alkaline, aerate your soil and mind your PH and there will be minimal plantain which used to be used in salad by the way. Dandelions, also once used in salad like, acid soil and lots of moisture, and again can be controlled with proper ph and water management.

Let’s say for the sake of argument that all this soil management is a big pain in the neck and you want to apply a chemical weed control to just wipe out all these plants because we like our lawns to be outdoor carpets. To be clear, I am not a big fan of a lawn that is more “weed” than grass myself, but I do think people can be a little extreme about having perfect lawns.

So you want to wipe out the weeds chemically. The bad news is that all herbacides only work well in dry weather. If the weeds are fat with water and happy, they don’t absorb the herbicide and it is far less effective. Most of us will think that the herbicide just needs to be a little stronger to work. This is a HUGE mistake. The label is the law and if you are applying the herbicide at a rate stronger than recommended, you are not only breaking the law but risking the herbicide running off into long island sound, hanging around in your soil, and poisoning the local fauna.

You will need to apply your herbicide several times AT THE RECOMMENDED APPLIED RATE to get rid of the weeds in a summer like this one. In wet weather, spray the weeds every week to ten days preferably NOT before precipitation is expected and not immediately after it rains. Give the weeds time to get thirsty so they absorb the herbicide, but don’t wait too long because if it rains immediately after your application it will all wash away and you will need to start all over again as well as risk interrupting the natural cycles of the ecosystem.

Remember that herbacides will also kill your soil culture. They will wipe out all the good microbes and fungi that help plants digest nutrients from the soil. Once you are “weed free”, if you want to minimize your ecological impact, get your soil tested, amend the ph, aerate, add composted materials  to the soil, spray with compost tea, and overseed three or four times a year. Maybe go after those weeds by hand so they don’t get away from you again (a stitch in time will save nine and all that). Start using proper watering and cutting practices so you don’t get in a weedy bind again.