14 Weed-Suppressing Perennials: How to Plant These Ground-Covering Champions for a Low-Maintenance Garden

Intro for Weed-Suppressing Perennials

Battling persistent weeds can feel like a never-ending garden chore. Strategic planting of the right perennials offers a smart, sustainable solution that reduces weeding time while enhancing your landscape’s beauty. Weed-suppressing perennials work by creating dense ground coverage that blocks sunlight from reaching weed seeds, effectively preventing their germination. These hardworking plants establish strong root systems that outcompete weeds for nutrients and water. Beyond their practical benefits, these perennials add texture, color, and seasonal interest to your garden while requiring minimal maintenance once established. Most thrive in temperate regions across USDA zones 4-9, making them versatile choices for various garden settings.

When to plant Weed-Suppressing Perennials

The ideal planting time for weed-suppressing perennials depends on your climate and the specific varieties chosen. In general, early spring and early fall provide optimal planting conditions in temperate regions. Spring planting (after the last frost when soil temperatures reach 10-15°C/50-60°F) gives plants time to establish before summer heat. Fall planting (6-8 weeks before the first frost) allows root development while temperatures are mild and rainfall is typically more reliable. Avoid planting during extreme temperature periods—either summer heat or winter freezes—as newly planted perennials will struggle to establish under stress conditions.

Best time to plant Weed-Suppressing Perennials

For cool-climate regions (USDA zones 3-6), plant between mid-April and early June or from late August through September. Warm-climate gardeners (zones 7-10) should aim for February to April or September through early November. Container-grown perennials can be transplanted throughout the growing season if you provide adequate water, though they’ll establish more easily during cooler periods. Bare-root perennials should be planted during their dormant season, typically late fall through early spring depending on your region. For maximum weed-suppressing effectiveness, plant when weeds are under control, giving your perennials a competitive advantage from the start.

Best Weed-Suppressing Perennial varieties to grow

• Lamium maculatum (Dead Nettle) – Forms a dense, quick-spreading mat with attractive silver-variegated foliage and delicate flowers, thriving in shade where many weeds attempt to establish.

• Geranium macrorrhizum (Bigroot Geranium) – Features aromatic foliage that naturally repels pests, spreads vigorously via rhizomes, and tolerates dry shade conditions.

• Nepeta × faassenii (Catmint) – Drought-tolerant with silvery foliage and lavender-blue flowers that attract pollinators while creating a dense weed barrier.

• Alchemilla mollis (Lady’s Mantle) – Forms lush mounds of scalloped leaves that collect morning dew in spectacular fashion while creating a tight ground cover.

• Stachys byzantina (Lamb’s Ears) – Features velvety silver foliage that creates a thick mat, tolerates poor soil, and discourages foot traffic with its soft but dense growth.

• Ajuga reptans (Bugleweed) – Rapidly spreading ground cover with glossy evergreen foliage and blue flower spikes, excellent for shady areas.

• Sedum (Stonecrop) – Low-growing varieties form tight carpets of succulent foliage that thrive in poor soil and full sun where many weeds struggle.

• Epimedium (Barrenwort) – Elegant shade-lover with heart-shaped leaves that creates a weed-resistant carpet under trees and shrubs.

How to plant Weed-Suppressing Perennials

Materials needed:
– Selected perennial plants
– Garden fork or tiller
– Compost or organic matter
– Mulch (bark chips, straw, or leaf mold)
– Garden trowel or spade
– Watering can or hose with spray attachment
– Landscape fabric (optional for severe weed problems)

Step-by-step planting:
1. Clear the planting area thoroughly of existing weeds, including their roots. For persistent weeds, consider laying landscape fabric with cutouts for your perennials.

2. Work the soil to a depth of 20-30 cm (8-12 inches), incorporating 5-7 cm (2-3 inches) of compost to improve drainage and fertility.

3. Arrange plants while still in their containers to visualize spacing. Position more aggressive spreaders where they have room to expand without overwhelming companions.

4. Dig planting holes twice as wide as the root ball but at the same depth. The crown of the plant should sit at soil level.

5. Gently remove plants from containers, loosen bound roots, and place in prepared holes.

6. Backfill with soil, firming gently around the roots to eliminate air pockets without compacting too heavily.

7. Water thoroughly, applying enough to saturate the root zone completely.

8. Apply a 5-7 cm (2-3 inch) layer of mulch around plants, keeping it from touching stems to prevent rot.

9. Space plants according to their mature spread, typically 30-45 cm (12-18 inches) for most varieties, but closer for faster weed suppression.

10. For maximum weed control, plant in a staggered or triangular pattern rather than in rows to create more comprehensive ground coverage.

How to grow Weed-Suppressing Perennials

Most weed-suppressing perennials prefer full sun to partial shade, with at least 4-6 hours of direct sunlight daily. Shade-tolerant varieties like Lamium, Ajuga, and Epimedium are exceptions, thriving in woodland settings. Water newly planted perennials regularly during their first season, providing about 2.5 cm (1 inch) weekly when rainfall is insufficient. Once established, most varieties become drought-tolerant, requiring supplemental water only during extended dry periods.

Fertilize sparingly in early spring with a balanced, slow-release organic fertilizer. Over-fertilization promotes leggy growth and can benefit weeds as much as your desired plants. Refresh mulch annually in spring before weed seeds germinate, maintaining a 5-7 cm (2-3 inch) layer.

For container growing, choose compact varieties like Sedum, small Nepeta cultivars, or Thymus. Use containers at least 30 cm (12 inches) deep with excellent drainage. Container-grown plants will need more frequent watering and winter protection in cold climates.

Encourage dense growth by trimming flowering stems after bloom, which often stimulates fresh foliage production. Some varieties, like Nepeta, benefit from a mid-season cutback to rejuvenate foliage and potentially trigger a second flowering.

Caring for Weed-Suppressing Perennials

Maintain vigilance during the establishment phase, removing any weeds that appear before they can set seed. Most weed-suppressing perennials require division every 3-5 years to maintain vigor and prevent center die-out. Spring or fall is ideal for this task, which also provides new plants to expand your weed-resistant coverage.

Common pests include slugs and snails, particularly on Hosta and Ajuga. Control them with iron phosphate baits or diatomaceous earth barriers. Powdery mildew may affect perennials in humid conditions with poor air circulation. Prevent by spacing plants appropriately and treat with neem oil or a baking soda spray (1 tablespoon in 1 gallon of water with a few drops of dish soap).

Crown rot can develop in overly wet conditions. Ensure good drainage and avoid overhead watering late in the day. Some aggressive spreaders like Ajuga and Lamium may need containment to prevent them from overtaking desirable plants. Install physical barriers or regularly trim edges to maintain boundaries.

Harvest flowering stems for arrangements just as blooms begin to open. Deadhead spent flowers to encourage reblooming in varieties like Geranium and Nepeta. Most weed-suppressing perennials don’t require winter protection in their hardiness zones, but a light mulch can protect crowns in marginal areas.

Understanding bolting in Weed-Suppressing Perennials

Bolting refers to the premature production of flowering stems, typically in response to stress conditions. While true bolting primarily affects vegetable crops, some perennials can exhibit similar stress responses. Heat stress during summer can cause certain perennials like Nepeta and Geranium to slow growth and reduce flowering. Unlike vegetables, this isn’t true bolting but rather a summer dormancy period.

To prevent stress-induced dormancy, provide afternoon shade in hot climates and maintain consistent soil moisture. Cutting back leggy growth mid-season often stimulates fresh foliage production and can trigger a second bloom cycle in fall as temperatures moderate. Some perennials, particularly those with spreading habits, may produce fewer flowers when overcrowded. Division every few years maintains plant vigor and flowering performance.

If summer dormancy occurs, avoid the temptation to fertilize heavily, which can stress plants further. Instead, provide moderate water and wait for cooler temperatures to trigger renewed growth. Unlike bolting vegetables, perennials will typically recover from summer stress without permanent damage to their ornamental value.

Why does Weed-Suppressing Perennial growth thin out?

• Age and overcrowding – Many perennials develop bare centers after 3-5 years as growth focuses on the outer edges; divide plants to rejuvenate.

• Insufficient light – Even shade-tolerant varieties need some light; thin overhanging tree branches if ground cover is becoming sparse.

• Nutrient depletion – Years of growth in the same location can exhaust soil nutrients; top-dress with compost annually.

• Pest or disease damage – Voles, slugs, or fungal diseases can create bare patches; identify and address specific issues promptly.

• Aggressive competition – Tree roots or neighboring plants may outcompete ground covers; create root barriers or choose more competitive varieties.

Companion planting for Weed-Suppressing Perennials

Spring-flowering bulbs (daffodils, tulips, crocus) pair beautifully with ground-covering perennials, which hide the bulbs’ fading foliage after bloom while maintaining weed suppression. Ornamental grasses create striking textural contrast with low-growing perennials and offer winter interest when many ground covers are dormant. Shrub roses benefit from underplanting with weed-suppressing perennials like Nepeta or Geranium, which hide their often bare lower stems while deterring weeds.

Avoid planting weed-suppressing perennials near delicate or slow-growing perennials that might be overwhelmed by more aggressive spreaders. Keep them away from vegetable gardens unless using contained varieties, as some can become invasive in cultivated soil. Some perennials, particularly those with dense mats like Ajuga, can compete with shallow-rooted trees and shrubs for water and nutrients, so maintain a small clear zone around woody plant trunks.

Seasonal calendar

Early Spring (March-April): Cut back previous year’s growth before new growth emerges; divide overcrowded clumps; apply slow-release fertilizer; plant new perennials after last frost.

Late Spring (May): Apply mulch to suppress emerging weeds; water during dry spells; deadhead early bloomers to encourage rebloom.

Summer (June-August): Water during drought periods; cut back spent flowers; trim back leggy growth on early bloomers to encourage fresh foliage.

Early Fall (September-October): Plant new perennials to establish before winter; divide spring-blooming perennials; reduce watering as temperatures cool.

Late Fall (November): Apply light winter mulch in cold regions after ground freezes; leave seed heads for winter interest and wildlife.

Winter (December-February): Plan next season’s additions; order bare-root perennials for spring planting; minimal maintenance required.

Problems & solutions

Common questions about growing Weed-Suppressing Perennials

How quickly will weed-suppressing perennials fill in?
Most varieties establish effective weed suppression within 2-3 growing seasons. For faster coverage, plant more densely initially (15-20 cm/6-8 inches apart) and divide established plants to fill gaps.

Can I plant these perennials through landscape fabric?
Yes, but it’s generally unnecessary and can limit their natural spreading ability. If dealing with aggressive weeds, use biodegradable landscape fabric that will decompose as your perennials establish.

How do I prevent aggressive spreaders from taking over my garden?
Install physical barriers like buried edging 15-20 cm (6-8 inches) deep around particularly vigorous spreaders like Ajuga and Lamium, or contain them in isolated beds surrounded by mowed lawn or hardscape.

Will these perennials suppress all types of weeds?
They’re most effective against annual weeds and seedlings. Established perennial weeds with deep roots may require manual removal before planting your weed-suppressing perennials.

How do I maintain pathways between weed-suppressing perennials?
Use stepping stones or mulched paths, allowing low-growing varieties like thyme or Sedum to fill spaces between pavers for a cohesive look that remains weed-free.

Can these perennials grow under trees?
Many, including Epimedium, Lamium, and Ajuga, thrive in the dry shade under trees. Provide supplemental water during establishment, as tree roots compete for moisture.

Do I need to remove these perennials to add bulbs to my garden?
No, simply lift sections of established ground covers in fall, plant bulbs, and replace the ground cover. The perennials will conceal fading bulb foliage after spring bloom.