Q & A with GardenWise horticulturist Carolyn Jones
Q: My husband put "Weed 'n Feed" on our lawn in August. After mowing the lawn several weeks later, he put the grass clippings in the compost. Will this destroy the micro-organisms and beneficial insects in the compost? Should I dig out the compost and start again?
A: I am not a big fan of weed and feed, for a number of reasons. If the product is cast near the roots of ornamentals, they can be damaged or killed. Care must be taken to protect children and pets. Weed and feed products don't work well on small-leaf weeds, such as clover.
Maintain a Healthy Lawn
A better approach is to keep your lawn healthy and growing well. It can then out-compete the weeds, which don't appreciate being mowed regularly. Then you can hand pull large weeds, such as dandelions, or spot treat them with the appropriate herbicide. Check at your local garden center for recommendations.
Adding grass clippings that have been treated with a herbicide to the compost is not recommended. However, it isn't necessary to dismantle the compost, as a year of composting and leaching will remove most of the chemical. However, to be on the safe side, don't use that compost on your food plants.
A free and easy way to fertilize your lawn is to leave the grass clippings on the lawn to decompose. They are 90% water and 9% fertilizer! To make this work, mow often (weekly works well) so clippings are less than 2.5 cm (1 in) long. Cut when the grass is dry so the clippings don't clump. Keep mower blades sharp. If using a rotary mower, attach a mulching blade.