Q: I am cleaning out my garage and have realized that I have too many containers of garden chemicals – herbicides, insecticides, fertilizers, etc. How do I decide what to keep and what to get rid of?
Before sorting through a bunch of containers that may have chemical residue dripped on the outside, I recommend putting on a pair of gloves. This is not just for safety reasons. Some garden chemicals (such as malathion and some antifungals) contain sulfur compounds that have a foul odor that is difficult to wash away. Nobody wants stinky hands.
First, find a sturdy box because you don’t want to throw this stuff into the regular trash. Any leaking containers should be bagged up securely and placed in the box. Be sure to keep the label with the container since they tend to fall off. Look at expiration dates and remove anything that is past its prime. If you don’t see an expiration date, but can’t remember when or why you bought it, it should go into the box. (Contact your waste management company for information on hazardous waste disposal).
For the remaining items, evaluate each one and answer the following questions. Did it work? Did you find out that the problem you bought it for was caused by something else? Sometimes a pest can be misidentified. Sometimes a problem that you thought was caused by a fungus was caused by a malfunctioning irrigation system.
Was the problem caused by conditions that are no longer relevant? Maybe those roses were planted too close together and they became infected with a fungus. You then replanted so they had more space and better air circulation and the fungus disappeared.
Do you still have the plant that this was purchased to treat? That treatment for peach leaf curl might not be needed if you removed your only peach tree.
Has this product been shown to harm the environment or non-target wildlife? Is there a less-toxic effective solution? Many people are still using old rat poison that is very harmful to predators and scavengers.
Fertilizers are usually in dry granular form and are good indefinitely if kept dry. I like to transfer them into lidded plastic containers.
Most garden chemicals have more than one application. For instance, most fungicides are effective against multiple fungal diseases. Pesticides such as insecticidal soap or horticultural oil are used against many different pests.
If you are uncertain about the safety, effectiveness, or environmental impact of any pesticide or herbicide, go to Pesticide information – UC Statewide IPM Program
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu