Sid Mullis: Controlling wild onion and wild garlic is tough

Don't prune hydrangeas yet

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Wild onions or garlic are some of the hardest-to-control weeds in the Augusta area for the average homeowner. Just about everyone calls the weed onions, but in almost all cases it is garlic.

Volunteers unload hydrangeas in preparation for the 2009 Hydrangeas Galore Plant Sale and Garden Tour. Hydrangeas should be pruned in the spring, not winter.  FILE
FILE
Volunteers unload hydrangeas in preparation for the 2009 Hydrangeas Galore Plant Sale and Garden Tour. Hydrangeas should be pruned in the spring, not winter.

Both wild garlic (Allium vineale) and wild onion (Allium canadense) are closely related and difficult to distinguish. Both plants are in the liliaceae plant family and are closely related to ornamentals such as day lilies and monkey grass. This family has many unique characteristics that make the use of selective herbicides possible.

Although many people don’t see them, these plants produce flowers at the end of a specialized leaf called a scape. At the top of this leaf, the plant produces a cluster of flowers, and once pollinated, these flowers can produce seed. Wild garlic flowers can produce bulblets (mini-plants) instead of seed. This characteristic is seen in mid-winter, when you can see a cluster of tiny plants where the flowers once existed.

Whether the flower cluster develops into seeds or bulblets, this structure will eventually shatter and release the seeds or bulblets. Of the two plants, wild garlic appears to be more invasive, appearing as a weed problem in agronomic crops in addition to in the garden and in turfgrass.

Wild garlic was introduced from Europe, and wild onion is native to North America. Both plants are edible but have a pronounced onion/garlic flavor.

The distinguishable characteristics are as follows: wild onion’s bulb has a reticulated (netlike) membrane or covering. The leaves occur from the base of the plant and tend to be flat. There is one bulb and no offset bulblets. Wild garlic’s leaves are hollow and tend to be formed higher on the stem (not where the stem comes out of the ground). It has offset bulblets.

Hand-weeding these plants can be difficult because they generally break off at the soil surface. Furthermore, garlic produces many underground bulblets that are difficult to remove if the plant is dug out. If your garden has loose friable soil, it might be possible to pull the plant up after a good rain. A thick layer of mulch can help prevent the emergence of these plants in the garden.

If you resort to herbicides, there are a few good options. One option is to use a nonselective herbicide such as glyphosate (Roundup and others). This herbicide can be used as a post-directed spray in mulched beds or natural areas, making sure to keep the spray off desirable plants. You cannot use it on the lawn.

Selective herbicides for lawns include imazaquin (Image) and 2, 4-D (Weed-B-Gon, Weed Control for Southern Lawns, Weedstop, etc.). These herbicides can be used safely over most turfgrasses. The herbicides appear to control both wild onion and wild garlic. Make sure to read and understand all herbicide labels before using them. It will normally take more than one application to kill the weeds.

Don’t prune
hydrangeas yet

Many people wind up pruning back their hydrangeas (Hydrangea macrophylla) during the winter after the leaves are gone. This is a mistake because they set their flower buds in the fall.

There is a rule of thumb we go by on when to prune flowering trees and shrubs. If they are a spring flowering plant (blooming before approximately May 1), prune them after they finish blooming because they set their flower buds the previous summer or fall. Examples are dogwoods, azaleas, forsythia and quince.

If they are summer flowering plants (or bloom after May 1), prune during the dormant winter months because they sets flower buds on the new wood. Examples are crape myrtles, altheas and roses.

Hydrangeas are an exception to this rule, because they flower after the first of May and are summer-flowering. The spring flower pruning rule applies to them. Hydrangeas produce flower buds in the fall, so pruning during the winter or spring will remove potential flowers.

After the main flush of blooms is over and the flower heads begin to fade, cut back the larger branches. This encourages new growth that produces next year’s flowers.

Hydrangeas will carry a few blooms all summer, so cut them back when the main flush is over (normally sometime in June).

Try to have all your pruning finished no later than late July or the first of August.

REACH SID MULLIS, THE DIRECTOR OF THE UNIVERSITY OF GEORGIA EXTENSION SERVICE OFFICE FOR RICHMOND COUNTY, AT (706)
821-2349 OR SMULLIS@UGA.EDU.


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