Taxonomy and Botany of Wild Violets
The plants that we are talking about in this article are called "common" or "wild" violets. Sounds simple, doesn't it? But, actually, this seemingly simple name covers a great variety of plants. Plant taxonomy lists Viola sororia (you will also see the name Viola papilionacea) as one of these plants.
Since Viola sororia is the kind most likely to be found growing as a lawn weed, it will be used as an example in this article.
Just remember that other types do exist. See "Types of Violas" below for more species information. To jump right to control information, scroll down to "How to Get Rid of Violets" below.
Characteristics of This Common Lawn Weed
Wild violets are best known for their namesake violet-blue flowers, although the blossoms do occur in other colors, such as white. Markings of a different color are often present, adding further beauty to this classic flower. A patch of purple violets growing on a lawn can be a truly gorgeous sight.
The foliage is more or less heart-shaped but may also taper to a fine point. The surface of the leaves is waxy. The plants commonly grow to be about 4-6 inches high, although, depending on type and conditions, they may grow taller than that.
They have a fibrous root system.
Various types of butterfly caterpillars treat the leaves as a food source, making wild violets valued by gardeners looking for plants that attract butterflies.
Where They Grow (Native Origin, Preferred Sun and Soil Conditions)
Viola sororia is native to eastern North America, according to Peter Del Tredici, in his very useful book for identifying weeds in the city (Wild Urban Plants of the Northeast, page 292).
These flowers grow in planting zones 3-9.
The plants prefer partial sun to partial shade. If you were growing them as a landscaping plant, the recommended soil would be moist to average. These conditions will promote an optimal display. But as anyone who has tried to get rid of them knows, these wildflowers do not need much help to survive. In fact, they may well survive a drought better than your lawn grass will.
Uses in Landscaping, Cuisine, Medicine
Because wild violets have pretty flowers, which bloom early and often, not everyone regards them as a type of weed, even when the landscaping area that they have chosen to call home is the lawn. Many homeowners choose to let these wildflowers grow as they will (and may even enjoy their presence). This can be because they:
- Want to avoid herbicide use.
- Do not wish to put any more effort into weed control than is necessary.
- Crave a more natural landscape design.
Moreover, they are edible weeds, as both the flowers and the leaves can be eaten. Young leaves are best for eating. The taste reminds one of nuts.
They also have medicinal qualities. According to Henriette's Herbal, "The salicylic acid found in all parts...is an active disinfectant and tissue solvent and can be applied externally to soften hard skin, corns and warts."
Do not confuse wild violets (Viola sororia, etc.) with African violets (Saintpaulia spp.). The latter, which are popular houseplants, are inedible. Furthermore, they are not even true violets; they were so named simply through floral resemblance. Their botanical name refers not directly to the Saint Paul of the Bible but to Baron von Saint Paul, a plant collector who was responsible for introducing them into Europe from Africa.
How to Get Rid of Violets
Now to the subject many of you have been waiting for: wild violet control. It is difficult to control them. Even if you keep them from going to seed, the fact is that some types can spread via stolons or rhizomes.
When trying to get rid of violets growing in a flower bed, some people spray Roundup (glyphosate) on them. But this assumes that the weeds are not growing right near other plants (since the Roundup chemical spray is non-selective) and that you are not an organic gardener.
More and more gardeners are getting away from using Roundup, viewing it as unsafe. Another option is to dig them up. Understand, however, that new plants will spring up from the tiniest bit of root left behind in the soil. That means two things if you have lots of these weeds in your flower bed:
- Lots of holes.
- You will probably have to repeat your control efforts, as you are bound to miss something.
As big a problem as that sounds like, trying to kill them when they are growing in the lawn is even worse. For one thing, all of the holes would leave your lawn looking like a moonscape. Moreover, you can't use mulch as an ally when trying to control violets that have become lawn weeds (whereas applying mulch is a smart preventive measure in a flower bed).
Unfortunately, that means that, if you are committed to killing violets in your lawn, you may well have to resort to using an herbicide. Products that contain triclopyr are recommended (unless your lawn is made up of bermudagrass). One such herbicide that is readily available at home-improvement stores is Weed-B-Gon Chickweed, Clover & Oxalis killer. Expect to have to follow up with repeat sprayings.
The optimal time to spray with the triclopyr is autumn. That is when plant foods are most active in traveling down to the root system, as the plant prepares for winter. Send triclopyr along for the ride, and you will be able to cause some damage. Very likely, this one application of herbicide will not kill the violets outright, however, so you might want to follow up next year in spring and then again in fall (as needed).
Because of the waxy coating on the violet leaves, some advise mixing a surfactant into the herbicide before spraying. "Surfactant" may sound like a fancy word, but just think of it as something that aids your herbicide so that it will work better. A surfactant helps out by reducing surface tension. Again, that may sound fancy, but all you really need to know is that a surfactant will help your herbicide to cut through the surface of the leaf and reach down to the area where it can do the most damage.
There are commercial surfactants you can buy, such as Spreader Sticker. But as GardenLine host Randy Lemmon explains, you can save money by mixing in dish soap, instead. "The normal dose is about a tablespoon per gallon of spray," says Lemmon.
Types of Violas
It is often difficult for the non-expert to identify the various wild violets beyond any shadow of a doubt. Part of the problem in identification lies in the fact that the plant in front of you at any given time may well be a natural hybrid plant.
Here are some examples of wild violet (Viola) species:
- V. odorata.
- V. blanda.
- V. canadensis.
- V. rotundifolia.
But it does not end there. Some violas are landscape plants with which you are probably quite familiar (even if you call them by a different name):
- Johnny-jump-ups (V. tricolor).
- Pansies (V. x wittrockiana).