For the purpose of the Hort Newsletter a weed is defined as a plant growing somewhere it is not wanted. For many gardeners, weeds are the downfall. Weeds create competition for nutrients and water. They can also restrict growth of desired plants by competing for space. The frustration with weeds leads some gardeners to turn to chemicals or give up on a garden plot altogether. Understanding weeds may be helpful in your gardening efforts.
Just like our garden plants, weeds can be annuals, perennials or biennials. Annual weeds, including henbit and spurge, germinate each year and complete their life cycle in one growing season. Perennial weeds such as, clover and bindweed, live at least two years and often reproduce by seed with the help of wind, water, animals and other means of dispersal. We all know a child, or perhaps you were the child, who loves blowing dandelion heads and making wishes as the wind disperses the seeds. Perennial weeds can sometimes spread by cuttings of roots or other vegetative plant parts as well. This capability can make managing these weeds a challenge.
Preventing weeds is the best management strategy. This includes using practices such as keeping the soil covered with a cover crop or mulch to prevent germination. Using drip irrigation to direct water to the desired plants rather than watering the entire garden area can also prevent weeds from germinating. Other prevention strategies include minimizing tillage. Deep tilling the garden damages the soil structure and brings weed seeds to the surface where conditions for germination are right. Occultation is the use of black tarps over the ground to kill weeds with the help of the sun. Depending on the persistence of the weeds this can take a couple weeks to months for successful eradication.
Weeds that have already established in a garden are often most effectively and safely removed by hand pulling. Though there are a couple of herbicides home gardeners can use there are consequences of using this method, including risk of damaging vegetable crops due to overspray. Cultivating the top one to two inches of soil can remove annual and young perennial weeds. If done on a regular basis this can effectively control their growth.
It is beneficial to knock out weeds before they are able to develop seeds to prevent reproduction. A single dandelion seed head has been reported to produce 150 to 200 seeds. (Something to remember next time you see the neighborhood child gathering stems in their yard!)
Integrated Pest Management (IPM) includes controlling weeds in the landscape. Using a variety of practices listed above will give the most effective management.
