Companion planting involves growing different plant species together to foster mutually beneficial relationships, enhancing their growth and productivity. This ancient agricultural practice, exemplified by methods like the “Three Sisters” (corn, beans, and squash), mimics natural plant communities to promote biodiversity and create a resilient garden ecosystem.
Why Companion Plant for Pear Trees
Companion planting offers several advantages for pear trees, contributing to their health and productivity. Certain plants deter common pests like codling moths or pear psylla by masking scents or releasing repellent compounds. Many also attract beneficial insects, including pollinators essential for fruit set and predators that feed on pests. Pollinators like bees are crucial for pear fruit production, as most varieties need cross-pollination. Companion plants can also improve soil health by enhancing nutrient cycling, fixing nitrogen, or improving soil structure and water retention. Ground cover plants suppress weeds, reducing competition for water and nutrients. Some plants may even contribute to disease prevention by promoting a healthier pear tree.
Recommended Companion Plants
Plants that attract pollinators are important, as pear trees generally need cross-pollination.
Borage: An annual herb with blue flowers that attract bees and other pollinators, blooming from spring through summer.
Comfrey: A perennial with deep taproots that attracts bumblebees and accumulates potassium, a nutrient beneficial for fruit development.
Calendula and Nasturtiums: Provide bright flowers that draw in bees and other beneficial insects, contributing to pollination.
Clovers (white, crimson): Attract ladybugs, lacewings, and parasitic wasps, while also fixing nitrogen in the soil.
Pest Deterrents
Plants with strong scents can deter common pear tree pests.
Garlic: Helps repel plum curculio, a pest that affects fruit trees.
Chives: Their pungent aroma deters various insects and can help prevent apple scab.
Marigolds: Release compounds from their roots that deter nematodes, and their strong scent can confuse other pests.
Tansy: Known for its strong scent that can help deter codling moths.
Peppermint Pelargonium (geranium): Has a strong scent believed to deter codling moth larvae from pupating near the tree base.
Soil Improvement
Some plants improve soil conditions and nutrient availability for pear trees.
Comfrey: A “dynamic accumulator” with deep taproots, drawing up minerals like potassium, calcium, and phosphorus from deeper soil layers. Its leaves can be cut and left to decompose as mulch, making nutrients available in the topsoil.
Clovers and Alfalfa: Valuable nitrogen-fixing legumes that enrich the soil with this essential nutrient.
Stinging Nettle and Yarrow: Also dynamic accumulators, bringing up iron, calcium, and other minerals from the subsoil. Their foliage can be used in a “chop-and-drop” method as nutrient-rich mulch.
Attracting Beneficial Insects
Attracting beneficial insects that prey on pests is another key strategy.
Dill and Fennel: Produce umbrella-like flower heads highly attractive to ladybugs, lacewings, hoverflies, and parasitic wasps, which are predators of common garden pests.
Yarrow: Attracts a wide range of beneficial insects, including ladybugs, lacewings, and parasitic wasps, providing them with nectar and pollen.
Cosmos and Sweet Alyssum: Annual flowers that attract lacewings, hoverflies, and parasitic wasps, providing continuous blooms.
These plants create a balanced ecosystem, reducing the need for chemical pest control.
Plants to Avoid
Some plants can negatively impact pear trees and should be avoided.
Competition
Plants that aggressively compete for water and nutrients can hinder a pear tree’s growth.
Aggressive turf grasses, large ornamental grasses (e.g., pampas grass), and rapidly spreading plants (e.g., mint, horseradish, Japanese knotweed): Have extensive root systems that can outcompete pear trees. Mint, in particular, spreads vigorously through underground runners.
Root crops (e.g., potatoes, carrots, beets): Can disturb the pear tree’s shallow root system during harvest, stressing the tree.
Alternate Hosts for Diseases
Certain plants act as alternate hosts for diseases that can affect pear trees.
Junipers (e.g., Eastern red cedar): Primary hosts for Gymnosporangium fungi, causing rust diseases like Cedar-Quince Rust and Pear Trellis Rust. Planting junipers nearby can facilitate the disease cycle, leading to orange spots on pear leaves and fruit.
Other rosaceous plants (e.g., hawthorn, quince, serviceberry, crabapple): Can also host these rusts and should be kept at a distance.
Allelopathy
Some plants release chemicals (allelochemicals) that inhibit the growth of nearby plants.
Black Walnut: Produces juglone, toxic to many plants, including some fruit trees. While pears are not as sensitive as apples, it is advisable to avoid planting them near black walnuts.
Elderberry, Himalayan Balsam, and Goldenrod: May also exhibit allelopathic effects that could hinder pear tree development.
Best Practices for Companion Planting
Implementing companion planting around pear trees requires careful planning.
Proper Spacing: Avoid placing companion plants too close to the pear tree trunk to prevent root competition. A distance of 2 to 3 feet is often recommended for herbaceous plants, and 12 to 18 inches for annual companions.
Sunlight Needs: Ensure companion plants do not overly shade the pear tree.
Watering: Accommodate the varying moisture requirements of all plants.
Soil Preparation: Prepare the soil with compost before planting to provide essential nutrients and improve soil structure.
Observation: Regularly observe the garden for issues or signs of competition, enabling adjustments.
Regional Suitability: Always consider the regional suitability of chosen companion plants, as local climate and soil conditions impact their success.