Wild violets are a common weed that can spread aggressively in lawns and gardens. While some people enjoy their delicate purple flowers in spring, others find them an unwelcome sight. Violets spread through seeds and rhizomes – horizontal underground stems. They thrive in shady, moist areas but can tolerate full sun. Getting rid of violets completely is very difficult, but there are several methods to control and reduce their spread.
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Why are wild violets considered a weed?
Here are some of the reasons why wild violets are considered a weed by many gardeners and lawn owners:
- They spread very quickly through seeds and underground rhizomes.
- Their shallow roots and low growth habit allow them to outcompete desired lawn grasses.
- Their leaves stay green all year and can take over lawns, leaving unsightly bare patches.
- Their spreading habit makes them good at crowding out and displacing other plants in flower beds and gardens.
- They are difficult to control and eradicate once established.
- Some people simply do not like the look of their purple flowers in turfgrass and consider them a weed on that basis.
So while wild violets are considered attractive spring blooms by some, their aggressive spreading and competitive nature means they are deemed undesirable weeds by many gardeners trying to maintain tidy lawns and cultivated landscapes.
How do wild violets spread so efficiently?
Wild violets have two very effective methods of spreading and colonizing new areas:
Seeds
Each violet flower produces around 50 seeds which drop to the ground when the flower dies back. These seeds have hard coats which allows them to remain dormant but viable in soil for many years. Whenever conditions are right, they will germinate and grow into new violet plants.
Rhizomes
The other method is vegetative spreading via rhizomes. Rhizomes are horizontal underground stems which grow just beneath the soil surface. Each year they extend outwards, producing roots and new shoots along their length. This allows an established violet plant to spread out in all directions and cover quite a large area over time.
So wild violets are able to propagate themselves very efficiently through both sexual reproduction from seeds and asexual reproduction from rhizomes. This helps them colonize areas very quickly.
How to control and prevent the spread of wild violets
It takes persistence and diligence to control wild violets. An integrated approach using a variety of methods is most effective. Here are some recommended techniques:
Remove flowers
Cutting or mowing flowers before they go to seed will reduce the number of new seeds added to the soil. Try to remove flowers just as their color starts to fade.
Hand dig
Small patches can be hand dug. Use a dandelion fork or similar long-handled tool to extract the entire plant along with its roots and rhizomes. Dig down about 4 inches. Dispose of the plants properly, do not compost them.
Solarization
In small areas, solarization with clear plastic sheeting can help kill violets. Cover the infested area with a sturdy plastic tarp and weigh down the edges with rocks or stakes. Leave it in place for at least 6 weeks over summer to promote heating of the soil and breakdown of plant parts.
Herbicides
Broadleaf selective herbicides containing 2,4-D, dicamba or triclopyr can be somewhat effective on violets. Products containing a combination of these active ingredients often perform better. Spray in spring or fall when nearby desirable plants are dormant. It will likely take multiple applications over more than one season to achieve control.
Vinegar
Household vinegar applied full strength to individual plants can sometimes damage their leaves, potentially weakening the plant over time. However results are mixed and most effective when treated repeatedly.
Corn gluten meal
This organic product inhibits the roots of germinating seeds when applied pre-emergently. It will not eradicate existing violet plants or kill seeds that have already germinated. But it can suppress new seedlings. Apply in early spring and reapply every 6-8 weeks where violets are sprouting.
Shade reduction
Wild violets thrive in shady areas. Pruning trees and shrubs to open up the canopy and increase sunlight penetration will discourage them over time. More sunlight also promotes thicker, more competitive turfgrass.
Aeration and overseeding
Aerating compacted soil provides better conditions for desired lawn grasses to grow. Overseeding bare patches with turfgrass seed blends further thickens up the lawn to suppress violets.
Mulch beds
Applying 2-3 inches of mulch in garden beds smothers any violets trying to establish. Organic mulches like wood chips and shredded bark also enrich the soil as they decompose.
Maintain turfgrass health
Following good cultural practices to maintain dense, vigorous lawn growth helps reduce opportunities for weeds like violets to invade. Ensure proper mowing height, irrigation, fertilization and soil pH for the grass type.
Patience and persistence
It takes consistent effort over more than one season to manage violets. Any control method must be repeated whenever regrowth occurs. Aim to deplete the seed bank in soil and gradually reduce the vigour of established plants until the infestation is at an acceptable level.
How to identify wild violets
There are a few common “wild” violet species found growing in North America. The most widespread are:
Common Blue Violet
Viola sororia
- Flowers light purple to lavender blue
- Leaves heart-shaped with scalloped edges
- Grows 3-6 inches tall
- Native species found throughout eastern and central North America
Confederate Violet
Viola sororia var. priceana
- Flowers dark violet-purple
- Leaves more triangular in shape
- Grows 6 inches to 1 foot tall
- Native violet of southeastern states
Woolly Blue Violet
Viola sororia var. missouriensis
- Flowers light blue to purple
- Leaves wide, heart-shaped, and fuzzy
- Grows 3-9 inches tall
- Found throughout central plains and prairie regions
There are also many garden-escaped ornamental violet species and hybrids that can become weedy in some areas. Violets spread by seed and rhizomes, forming dense colonies in moist shaded sites.
When is the best time to control wild violets?
Early spring and early fall are the ideal times to treat wild violets for the best results:
Spring
- Plants are young and more vulnerable
- Can remove flowers to prevent seed spread
- Herbicides are readily absorbed and translocated to roots and rhizomes as plants are growing rapidly
- Avoid flower beds where desired plants are emerging
Fall
- Plants are redirecting energy to roots, improving herbicide effectiveness
- Less risk to surrounding dormant plants
- Can combine control measures with lawn overseeding
- Avoid late fall when ground may freeze
Follow-up control measures are often needed in both spring and fall to achieve the best long-term results.
Natural control methods for wild violets
For gardeners wishing to avoid synthetic herbicides, some possible natural control options for wild violets include:
Corn gluten meal
This organic byproduct derived from corn processing inhibits germinating seeds. Spread at a rate of 20 lbs per 1000 sq ft in early spring to prevent new violets.
Vinegar
Spray full strength household vinegar directly on individual plants. The acetic acid can burn leaves. Repeat as needed.
Boiling water
Carefully pour boiling water directly on violet plants to scald them. Avoid boiling water coming into contact with desired plants.
Flame weeding
Using a propane torch to briefly pass flames over young violet seedlings and small plants may destroy them.
Solarization
Covering areas with clear plastic sheeting can heat soil and kill plants underneath.
Salt
Spreading ordinary table salt or rock salt directly on violet leaves may dehydrate and destroy plants. Avoid getting on desired plants.
Mulching
Applying 2-3 inches of mulch in beds and borders suppresses violets by blocking light.
Hand weeding
Manually digging out plants, including all roots and rhizomes, can control small patches.
Conclusion
Wild violets are tricky weeds to eliminate entirely from lawns and gardens due to their propagation by seeds and underground rhizomes. But following an integrated plan of manual removal, herbicide application, and cultural practices that favor the growth of desired plants can keep them under control. Tackling violets when they are small and vulnerable in spring and fall offers the best chance of success, especially if efforts are repeated consistently over more than one growing season.