What to Plant to Reduce Pest Pressure in Pennsylvania Yards

Pennsylvania yards face a range of pests: chewing and sucking insects, soil-borne nematodes, slugs, vole damage to bulbs and bark, and browsing by deer. Thoughtful plant selection and landscape design can reduce pest pressure by creating habitat for beneficial predators and pollinators, using plants that repel or trap pests, and improving soil health so plants are less attractive to pests. This guide explains which plants and planting strategies work well in Pennsylvania (USDA zones largely 5-7), why they work, and practical, actionable plans you can implement in a suburban or small-acreage yard.

Core principles: why plants matter for pest control

Healthy, diverse plantings reduce pests in three main ways:

• They support natural enemies (predators and parasitoids) by providing nectar, pollen, and overwintering habitat.
• They physically deter or distract pests (repellent plants, trap crops, and unpalatable species).
• They improve soil and plant vigour (cover crops, biofumigant species, and deep-rooted perennials) so plants tolerate or recover from pest pressure more readily.

Adopt these principles before picking species: increase plant diversity, include continuous bloom from spring to fall, use native species where possible, and combine perennial habitat with annuals and cover crops in vegetable beds. Below are practical plant choices and how to use them.

Plants that attract and sustain beneficial insects

Beneficials include lady beetles, hoverflies, lacewings, predatory ground beetles, and many parasitic wasps. They need accessible nectar and pollen (often from small, open flowers) and shelter. Plant strips and borders of insectary plants to establish a resident beneficial community.

• Umbellifers (Apiaceae): dill, fennel, cilantro/ coriander (when bolting), Queen Anne’s lace.
• Small-flowered composites and asters: yarrow (Achillea millefolium), coreopsis, asters, goldenrod (late season).
• Brassicaceous and fast annual attractors: buckwheat (excellent rapid-flowering insectary), alyssum (sweet alyssum), phacelia.
• Native perennials: bee balm (Monarda), coneflower (Echinacea), black-eyed Susan (Rudbeckia), asters.

Planting tips:

• Establish a 3-6 foot insectary strip along a fence or garden edge with a mix of umbels, composites, and fast annuals like buckwheat to provide continuous bloom.
• Include late-season bloomers (asters, goldenrod) to sustain parasitoids and predators into fall.
• Avoid broad-spectrum insecticides; they destroy the beneficial community you’re cultivating.

Plants that repel or confuse pests and trap crops to divert them

Certain plants have compounds that deter pests or act as sacrificial trap crops. Use these strategically rather than as sole solutions.

• Marigolds (Tagetes patula): certain marigold species reduce root-knot nematode populations when planted as a companion or cover crop around susceptible vegetables. Use as border rows or in pots near tomato and pepper beds.
• Garlic and chives: repellent to some aphids, beetles, and Japanese beetles; interplant around roses, brassicas, and tomatoes.
• Nasturtium: acts as a trap crop for aphids, cabbage white caterpillars, and some flea beetles. Plant as a sacrificial plant near brassicas and cucurbits.
• Tansy and rue: historically used as repellents; tansy can be invasive and should be used cautiously.
• Sunflowers: can act as a physical trap and provide habitat for beneficial predators; their large flowers host predatory insects and birds that eat pests.

Practical rules:

• Plant trap crops at the outer edge of the garden to lure pests away from main crops; remove or treat trap crops before pest populations build and disperse.
• Marigolds suppress nematodes best when multiple rows are used as a dedicated cover crop for a season, or when roots and foliage are incorporated as green manure.

Native shrubs and trees that reduce long-term pest problems

Woody plants can support birds and predatory insects, creating a landscape-level reduction in pests. Choose native species that provide berries and structural diversity.

• Spicebush (Lindera benzoin): hosts native butterflies (spicebush swallowtail) and provides dense cover that supports insectivorous birds.
• Serviceberry (Amelanchier spp.): early spring flowers attract pollinators; berries feed birds that consume insect pests.
• Elderberry (Sambucus canadensis): fast-growing native shrub that supports pollinators and birds.
• Viburnums and dogwoods: offer spring flowers for pollinators and fruit for birds later in the season.

Landscape placement:

• Establish a mixed hedgerow of 4-8 species along field edges or property lines. This concentrates predators and birds that forage into the yard.
• Avoid planting large monoculture trees that are highly attractive to pests you want to avoid (for example, some linden or crabapple varieties can host high Japanese beetle populations).

Plants that reduce soil pests and protect root health

Soil health is foundational. Certain cover crops and green manures can reduce nematode pressure, break pest cycles, and improve structure.

• Mustard cover crops (brassicas used as biofumigants): when incorporated green, certain mustard species release compounds that suppress nematodes and soil-borne pathogens.
• Buckwheat: quick to establish, attracts pollinators and beneficials, and is a good short-season smother crop.
• Crimson clover and other legumes: build nitrogen and attract beneficials; include in rotation to improve soil.
• Winter rye: helps prevent erosion and reduces some soil pest problems when used in rotation.

Practical schedule:

• After an early-season vegetable harvest, sow buckwheat for 6-8 weeks to attract beneficials and smother weeds.
• For nematode-prone beds, consider a mustard biofumigant cover for a season, followed by a non-host rotation crop.

Bulbs and perennials to reduce vole and deer damage

Small mammals and deer are important non-insect pests in Pennsylvania. Plant choices and planting techniques can reduce damage.

• Deer-resistant bulbs and perennials: daffodils (Narcissus), alliums, snowdrops, fritillaria. Deer generally avoid these due to toxic alkaloids or strong odors.
• Groundcover choices: avoid thick, mat-forming evergreen groundcovers next to trunks (which encourage vole activity). Instead use coarse mulches and avoid piling mulch against stems.
• Shrubs deer avoid: boxwood suffers from deer browsing; better alternatives include inkberry (Ilex glabra), mountain laurel (Kalmia latifolia), and barberry (non-native barberry can be invasive; choose carefully).

Protective measures:

• Plant vulnerable bulbs in wire baskets or plant taller-blooming bulbs like daffodils mixed with tulips; the daffodils often deter rodents from eating bulbs nearby.
• Use hedgehog nets and raised planting beds in severe vole areas to exclude voles from high-value plantings.

Companion planting and layout for vegetable gardens in Pennsylvania

Pairing specific herbs and flowers with vegetables has practical benefits. Below is a recommended companion layout and why it works.

• Tomatoes: interplant basil and borage. Basil can reduce thrips and possibly whitefly pressure; borage attracts syrphid flies and pollinators and may improve tomato vigor.
• Brassicas (cabbage, broccoli): surround with nasturtiums as trap crops, plant chives and garlic near susceptible plants to reduce aphids, and use rows of marigolds to suppress nematodes.
• Cucurbits: plant nasturtium and sunflowers at borders to attract cucumber beetles away; maintain strips of buckwheat to draw pollinators that also bring predators.
• Beans and peas: interplant with buckwheat and alyssum to attract natural enemies; keep a clover strip nearby to host beneficials.

Layout tip:

• Use alternating rows or blocks rather than large monoculture beds. Mixed plantings make it harder for pests to find hosts and create microhabitats for predators.

Maintenance practices that enhance plant-based pest control

Plant choice alone is not enough–maintenance matters.

• Avoid routine, broad-spectrum insecticide use. Targeted treatments (insecticidal soaps, Bacillus thuringiensis for caterpillars) used only when thresholds are exceeded preserve beneficials.
• Keep plantings healthy: correct pH and fertility reduce pest attraction. Over-fertilized, lush growth attracts aphids and caterpillars.
• Mulch thoughtfully: use coarse wood chips away from trunks to reduce vole habitat; avoid overly dense mulch against plant crowns.
• Provide water and seasonal shelter: small brush piles or a log pile at the edge of the yard are excellent overwintering habitat for predators but keep them away from vegetable beds to avoid harboring rodents.

Sample one-year plan for a small Pennsylvania yard (actionable)

• Spring: install a 4-6 foot insectary strip with dill, fennel, alyssum, and coreopsis. Plant daffodils and alliums in beds susceptible to vole damage.
• Early summer: sow buckwheat in a 10-20 foot block after early lettuce and peas are harvested. Interplant marigolds around tomato and pepper beds; plant nasturtiums at brassica edges.
• Mid summer: add borage and basil among tomato plants; maintain continuous bloom by replacing spent annuals.
• Fall: plant a mustard cover crop or incorporate a rotation like rye/crimson clover to improve soil and suppress nematodes. Prune and tidy insectary perennials but leave some stems for overwintering beneficials.
• Year-round: add a mixed native hedgerow (serviceberry, spicebush, elderberry) in a single season or over two seasons to support birds and predatory insects.

Final takeaways

• Diversity is the most powerful single strategy: mix native perennials, herbs, and annual insectary plants to sustain beneficials and reduce pest outbreaks.
• Use plant-based tactics in combination: trap crops, repellents (garlic, chives, marigolds), and habitat-providing natives create a multi-layered defense.
• Prioritize soil health and avoid broad-spectrum pesticides to allow predator populations to build.
• Plan seasonally: ensure continuous bloom, rotate vegetable beds with cover crops, and pair vulnerable plants with deterrent or companion species.

By choosing the right mix of plants and designing your landscape to support beneficial insects, birds, and soil health, you can substantially reduce pest pressure in Pennsylvania yards while creating a more resilient, attractive landscape.