By Kathy Conner Cornell
VCE Southside Master Gardener
I have many herbs, native perennials, daylilies and roses in my garden but to be perfectly honest, I have world-class weeds. It is no surprise. I am surrounded by hay fields on three sides and a cow pasture on the other. So I have what would be considered field weeds, big ones. Admittedly, it is difficult to keep up and to be honest, my friends with pristine gardens have husbands who are very involved. Well, I have to settle for a husband that does all the cooking and to me, I am getting the better end of the bargain.
Weeds disrupt native habitats and interfering with the wildlife that rely on these habitats. Weeds can stress the plants around them by robbing the nutrients, moisture and restricting airflow. Often weeds are vectors, meaning they bring disease and insect pests to desired plants. There are some that are allelopathic and produce substances that can inhibit germination or stunt growth of surrounding plants.
This Wild Lettuce, Latuca canadensis, is a native plant that becomes weedy when found in our garden beds. It is a biennial so easy to control as long as you don’t allow it to set seeds.
It is imperative that when you are weeding to know what the weed is, its life cycle, what factors influence its reproduction, and what are the weak spots. This takes some research. As the gardening guru Margaret Roach says, “We can’t successfully fight an opponent that we can’t identify”. Right now I can’t give you a great source to help you on your search. I am trying to identify a weed in my yard and did find a clue in University of Delaware publication “Weeds of the Northeast” by C. E. Phillips. It identifies the plant by leaf shape. If you search for it, the first few hits will want to sell the publication to you but the University website allows a free PDF download. Remember when you search you will get much better information using the botanical name and go to sites ending in .edu or .gov because this information is scientifically based.
The most important thing to learn about weeds is to not allow them to go to seed. That is the part that makes the problem one that you’ll be fighting for years. As my Integrated Pest Management Professor Chuck Cornell said “let ‘um go to seed one year and you’ll fight them for seven”. If you can do nothing else, cut off seed heads, better yet the flower heads and do NOT put seed heads in the compost pile. You’ll be giving them the right conditions to thrive. Remember a weed is a plant that is in the wrong place. Therefore, don’t plant invasive alien plants because they will become weeds. For example, English ivy, Hedera helix, is very aggressive and it will eventually spread in partly shaded lawn areas, grow up and out crawling up as well as choking healthy trees.
Just like herbaceous plants, weeds can be annual, biennial or perennial. Annual ones are the easier clean up. No need to worry about getting all the roots for the plant will die out anyway. Again, don’t let it go to seed. Common chickweed, Stellaria media, is a winter annual that will die out in the hot sun.
Biennials live for two years. Generally the first year they grow a basal rosette, the second year they grow tall, flower, set seed and die. Therefore, as long as you cut it back the first year and to the ground the second year, it will die out. When I first moved here I found a lot of Burdock, Arctium minor, a biennial. It gets these seed pods that we called cockleburs. Once my Mom was irritated with my Dad and what she pulled off of my sister and I when we came in from playing, she put on my Dad’s side of the bed. That story is amazing if you know my Dad, Grover. The plant does have a lot of medicinal properties but to me, it was a weed. Because of its biennial properties I was able to control it and that is a weed I haven’t seen in years. Again, I cannot express how important it is to not let it go to seed. Seeds are the only way biennials can reproduce.
The weeds that really get us are the perennials. Lots of perennials spread by rhizomes or stolons. It is imperative for control to get the entire root system. I admit I have pulled out wiregrass roots, which is Bermuda grass Cynodon dactylon, that were 20 feet long and did not reach the end. Whatever little piece is left will regrow. If it is impossible to get the entire root, you might have to consider stronger methods. Soil solarization is an option. Basically you cover the ground with plastic during the hot summer and it will kill the weeds, nematodes and the latent seeds. You will need to anchor the plastic completely around the bed using bricks, lumber or rocks. But you must have mulch, plants, or a quick growing groundcover to blanket the soil once you remove the plastic. If not, new young weeds blown in or bird delivered seeds will be happy to fill it up. Weeds just love empty spaces.
Using herbicides is not recommended on a routine basis and be sure you use the suggested personal protective equipment. Always read the label and follow the instructions, it is the law to use the product in the recommended way. I know you can’t read that tiny print but you can find any label online or use a magnifying glass. Make sure the weed is listed on the label.
There is landscape cloth out there. It was supposed to have the advantage of allowing water to move through unlike black plastic. For the most part, it is useless and the weeds will be just as happy to grow on top of the cloth.
During a recent podcast Joe Lamp’l and Margaret Roach shared that they enjoy weeding and Margaret admitted she gets into a Zen zone when she weeds. While we are all still practicing ‘social distancing’ due to COVID-19, and all county buildings are closed to the public, if you have gardening questions, you can best reach an Extension Master Gardener or Extension staff member by sending an email to firstname.lastname@example.org or email@example.com. Keep washing your hands and find your Zen moment when you weed.