How to Prevent and Control Weeds

The most important weed management tasks are done before planting. Good site preparation includes scouting for perennial weeds and controlling them before planting. Manual or mechanical control of perennial weeds is difficult and costly once the bed is established.

There are three options for controlling perennial weeds:

Cultivation, fumigation, or systemic postemergence herbicides (Roundup-Pro or Finale). Before planting, Roundup-Pro (sold under many other trade names in the consumer market) and Finale can be used to control annual and perennial weeds, but timing of the application is critical to obtain maximum perennial weed control.

Weeds can also be controlled by cultivation or use of a herbicide, but some weeds will still need to be pulled by hand. Weeds are easier to pull after a rain or irrigation.

Weeds can only be controlled by cultivation early in the season. As annual flowers grow, the feeder roots that spread between plants are likely to be injured by cultivation. In addition, cultivation stirs the soil and uncovers weed seeds that can then germinate.

Any herbicide used in flower beds must be chosen carefully. Read the label: no one herbicide can be used safely on all annual flowers. Herbicides that are labeled for some but not all flowers include:

• Betasan
• Enide
• Surflan
• Treflan

Time and rate of application will vary with the herbicide selected. A preemergence herbicide can be used to prevent many weed seeds from germinating. Some preemergence herbicides are applied before planting, others are applied after planting but before weeds emerge.

The flower bed should be weed-free when the herbicide is applied. Only a few postemergence herbicides can be used to control grassy weeds after flowers have become established.