Do Ground Cover Plants Prevent Weeds?
Yes, ground cover plants can prevent weeds by shading the soil, competing for water and nutrients, and forming a dense mat that blocks weed seedlings. However, they are not a magical solution—success depends on choosing the right plants for your site, preparing the soil well, and giving the ground covers time to fill in. Used correctly, they reduce weeding work dramatically over time.
How do ground cover plants stop weeds from growing?
Ground cover plants stop weeds in several natural ways. First, they create a thick layer of leaves and stems that blocks sunlight from reaching the soil. Most weed seeds need light to germinate, so without it, they stay dormant. Second, the roots of ground covers spread out and take up water and nutrients quickly, leaving little for weed roots. Third, some ground covers release natural chemicals that slow down weed seed growth—a process called allelopathy.
When you plant them close together, the plants also create a physical barrier. Weed seeds that blow onto the surface cannot find bare soil to root into. Over time, as the ground cover matures, the canopy becomes so thick that even persistent weeds like dandelions struggle to push through.
What are the best ground cover plants for weed prevention?
The best ground cover for weed control depends on your climate, sun exposure, and soil type. Here are some top performers that form dense mats:
- Creeping thyme – thrives in full sun, low-growing, and releases a pleasant scent. Works well between stepping stones.
- Sedum (stonecrop) – excellent for dry, sunny spots. Forms a tight mat of succulent leaves that weeds cannot penetrate.
- Vinca minor (periwinkle) – very fast-spreading in shade or partial shade. Its evergreen leaves block light year-round.
- Pachysandra – a classic choice for deep shade under trees. Forms a uniform carpet.
- Liriope (lilyturf) – good for edging and slopes. Its clumping habit fills in quickly.
- Juniper (low-growing varieties) – woody ground cover for large sunny areas. Almost impenetrable once established.
If you need to cover a large area on a budget, consider buying a premixed ground cover seeds that includes several of these species. The mix increases your chance of success in different microclimates.
How long does it take for ground covers to choke out weeds?
Patience is key. Most ground cover plants need one to three growing seasons to fully fill in and stop weeds. Fast growers like creeping Jenny or Ajuga can form a solid carpet in one season if planted close together. Slower ones like pachysandra or juniper may take two or three years.
During that establishment period, you will still need to pull weeds. The ground cover is not yet dense enough to block all light. Plan to weed regularly for the first summer. Once the plants touch each other and create a closed canopy, weed pressure drops drastically.
To speed things up, space plants closer than the recommended distance. For example, if the label says 12 inches apart, try 8 inches. More plants means faster coverage and less time for weeds to take hold.
Can ground cover plants completely eliminate weeding?
No, but they can reduce it by 80 to 90 percent once established. You will still see an occasional weed pop up, especially along edges or where the ground cover is thin. Wind-blown seeds like maple keys or thistle can land on top of the mat and sprout if there is even a tiny bit of organic matter. Also, some aggressive weeds like poison ivy or English ivy can invade a ground cover bed if left unchecked.
To keep weeding to a minimum, walk through your ground cover patch once a month and pull any invaders while they are small. Use a hand weeding tool to gently pop out weeds without disturbing the roots of your ground cover.
Think of ground cover as a weed suppressant, not a weed eliminator. In return for a little early effort, you gain years of less weeding work.
What mistakes can make ground cover plants fail against weeds?
Even the best ground cover will let weeds take over if you make these common mistakes:
- Planting in weedy soil – If you skip removing existing weeds and their roots, those weeds will grow right through the new plants.
- Not spacing correctly – Planting too far apart leaves bare soil where weeds love to germinate.
- Choosing the wrong plant for your site – A sun-loving ground cover in shade will be thin and weak, inviting weeds.
- Failing to water during establishment – Stressed plants grow slowly, giving weeds a head start.
- Over-fertilizing – Too much nitrogen feeds weeds more than ground covers.
- Ignoring mulch – A layer of organic mulch between plants helps block light and holds moisture for the first season.
Another big mistake is using an aggressive weed barrier fabric that does not break down. While it may help short-term, it can prevent the ground cover from rooting deeply and spreading naturally. If you must use fabric, choose a biodegradable landscape fabric that will decompose after a year or two.
How should you prepare soil before planting ground covers?
Good soil preparation is the single most important step for weed prevention with ground covers. Follow these steps:
- Remove all existing weeds – Pull or dig out every weed, including roots. Use a hoe or hand trowel. Do not just mow them down.
- Test the soil – Most ground covers prefer slightly acidic to neutral soil (pH 6.0 to 7.0). Add lime if too acidic, or sulfur if too alkaline.
- Loosen the soil – Till or dig to about 8 inches deep. This helps roots spread quickly.
- Add organic matter – Mix in 2 to 3 inches of compost or well-rotted manure. This improves drainage and fertility.
- Level the area – Rake smooth to avoid low spots where water pools and weeds grow.
- Water the bed well – Let it settle for a day or two before planting.
- Consider a pre-emergent – Apply a natural corn gluten meal to prevent weed seeds from germinating. Do not use chemical pre-emergents, which can harm young ground cover roots.
Once the bed is prepared, plant your ground covers and water them in. A drip irrigation system on a timer can make watering consistent and avoid washing away soil.
Simple checklist for using ground cover plants to prevent weeds
| Step | Why it matters |
|---|---|
| Remove all weeds before planting | Prevents competition from day one |
| Choose a ground cover suited to your light and soil | Healthy plants spread faster, shading weeds |
| Space plants 20% closer than label says | Quicker fill-in, less bare soil |
| Apply 2 inches of organic mulch between plants | Blocks light and retains moisture |
| Water deeply once a week for the first season | Encourages deep roots that beat weeds |
| Pull any weeds you see before they flower | Prevents new weed seeds from dropping |
| Replenish mulch each spring until cover fills in | Maintains weed barrier during transition |
Use this checklist before and after planting. It will help you avoid the biggest mistakes and get the weed-blocking carpet you want.
Do ground cover plants work on slopes or in rocky areas?
Yes, ground covers are especially effective on slopes where mowing is difficult and erosion is a problem. Their roots hold the soil in place while the foliage stops weeds. On a steep bank, plants like creeping juniper, cotoneaster, or daylilies form a living weed barrier that also reduces runoff.
In rocky areas or between flagstones, low-growing plants like Irish moss or thyme fill the cracks and prevent weed seeds from finding a home. The key is to plant them in small pockets of soil and keep the area free of weeds for the first few months.
One tip for slopes: use a burlap erosion control mat over the soil before planting. Cut holes for your ground cover. The mat will hold the soil and block weeds while the plants establish.
How do you maintain ground covers long-term to keep weeds out?
Maintenance is light after the first year, but not zero. Each spring, remove any dead leaves or debris that have collected on top of the ground cover. This prevents thatch, which can harbor weed seeds. Also, trim back any ground cover that spills onto walkways or lawns, as overgrown edges can hide weeds.
Every three to four years, consider dividing or thinning the ground cover if it becomes too thick. This improves air circulation and reduces disease. You can replant the divisions elsewhere or share them.
Keep an eye out for invasive climbing weeds like bindweed or morning glory. They can snake up through ground cover and smother it. Pull these immediately, roots and all.
If bare patches appear, fill them in with new plants or transplant from other areas. Bare soil is an open door for weeds.
Can you use ground cover plants with other weed control methods?
Absolutely. In fact, combining methods works best. Use mulch, edging, and proper spacing alongside ground cover. For example, install a metal or stone edging strip around the bed to stop grass from creeping in. Then apply a layer of mulch while the ground cover is young. Once the ground cover fills in, the mulch breaks down naturally and feeds the plants.
Another powerful combination is using a pre-emergent weed control that is safe for ground covers. Read labels carefully—corn gluten meal is a natural option that prevents weed seeds from sprouting without harming established plants.
For extra stubborn areas like a bed near a fence where birds drop weed seeds, consider putting a layer of cardboard under your mulch. It kills seeds and young weeds without chemicals. Just make sure to wet it thoroughly so it stays put. After a few months, it decomposes and becomes part of the soil.
Will ground cover plants attract pests or cause other problems?
Some ground covers can become invasive in certain climates—like English ivy or pachysandra in parts of the eastern U.S. Always check with your local extension office before planting. Also, very dense ground covers can hide slugs from predators. If you see slug damage, use an organic iron phosphate slug bait that is safe for pets and wildlife.
Thick ground covers may also create a damp microclimate at the base, which can lead to fungal issues. This is rare but more common in shade. To prevent it, do not overwater and keep the ground cover from getting too deep and matted. Occasional raking or thinning helps air circulate.
On the plus side, ground covers provide excellent habitat for beneficial insects like ground beetles, which eat weed seeds and pests. So the overall effect is positive for your garden's health.
Ground cover plants are a natural, low-work way to prevent most weeds. They take a little time to establish, but once they do, you will spend far less time weeding. Pick the right plants, prepare the soil well, and follow the simple steps above. Your garden will thank you with less work and more green.