Overview
Weeds are really plants in garden landscapes growing where they do not belong. Effective removal and control can minimize garden landscape maintenance. How do we effectively remove and control these undesirables?
Basic Strategies
Deep weeding and mulching are tried and true methods of control. Used improperly or alone these may become repetitive tasks that do not minimize maintenance. Avoid creating extra work by:
- Identifying problem plants,
- Categorizing them according to growth and reproductive habits,
- Knowing their growth characteristics, and
- Experimenting with sturdy new tools that make maintenance easier.
Problem Plants - Categories, Examples and Characteristics
- Annual grasses: Crabgrasses (Digitaria spp.) are prolific because they flower quickly and produce abundant seeds. Annual grass seeds also blow in from outside the bed(s).
- Perennial grasses: Quackgrasses (Elytrigia repens) leave runners (rhizomes); the smallest piece can sprout a new plant.
- Annual broadleaf plants: Common cocklebur (Xanthium strumarium), shepherd's-purse (Capsella bursa-pastoris), common lambsquarters (Chenopodium album) and common chickweed (Stellaria media) are all prolific seed producers. Their seeds also possess mechanical dispersal devices which allow them to "hitch-hike" far afield.
- Biennial broadleaf plants: Wild carrot / Queen Ann's Lace (Daucus carota) and Poison hemlock (Conium maculatum) grow two seasons before producing flowers and abundant seeds. They also possess deep tough taproots that provide staying power.
- Perennial broadleaf plants: Dandelion (Taraxacum officinale) and curly dock (Rumex crispus) flourish and grow larger each year until their superlative taproots are destroyed.
Herbicides - One Follow-Up Strategy
Herbicides are chemical substances used to destroy or inhibit plant growth. Many new herbicides are safe, effective landscape allies when used carefully and according to directions. Herbicides can:
- Inhibit seed germination,
- Prevent cell division and growth,
- Destroy cell membranes, and
- Disrupt photosynthesis.
Herbicide classification is based on application in specific parts of the plant life cycle, on which group of plants it is most effective, and how each works. These classifications strengthen reasons for knowing exactly what plants landscape gardeners want to eliminate.
- Pre-emergent herbicides: control seedlings before they emerge or appear aboveground; most effective when applied a few weeks before plant germination and emergence; will not control established weeds. Pre-emergent herbicides act on specific plant groups.
Preen® Garden Weed Preventer, a product of © Lebanon Seaboard Corporation, is one example of a pre-emergent herbicide. It prevents growth of annual weeds in flower and vegetable beds, and around trees and shrubs for up to three months.
Preen® works by creating a chemical barrier in the top 1 to 2 inches of soil. This barrier prevents cell division in developing seeds. It does not destroy existing weeds, but prevents new weeds from growing. Thorough and extensive weeding is necessary before application of Preen®.
- Post-emergent herbicides: applied after emergence of a plant from the soil; some act upon new seedlings while others only on actively growing plants. Some post-emergent herbicides work through soil applications. Most, however, are contact herbicides that kill or weaken plants upon even casual or misdirected contact. Use requires painstaking care.
Roundup®, a product of ©ScottsMiracle-Gro, is a systemic contact herbicide that active growing plants absorb. It usually kills the entire plant, including roots. It is rainproof in 10 minutes, and results start to show in about 6 hours.
Landscape Fabrics – Another Follow-Up Strategy
Landscape fabric for weed control yields successful results when utilized properly. It is not an "install once and forget" method of landscape maintenance. Landscape gardeners should:
- Carefully analyze and then prepare project sites to make landscape maintenance easier,
- Make use of itemized checklists before planting and/or mulching, and
- Be vigilant about keeping up pest control for rips and tears in fabric and weed control from viable seeds that germinate in camouflaging mulch.
Mulch - The Finishing Touch
Mulch is the finishing touch for any landscape bed or border. It fulfills many roles in landscape maintenance. However, vigilance is necessary. Mulch may suppress weed growth, but seeds will continue to sprout and grow in top layers. Any kind of mulch makes a perfect germination bed.
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