7 Plants to Never Grow Next to Apple Trees, According to Gardening Experts

Fennel

Fennel (Foeniculum vulgare) makes a poor companion plant to most plants, says Lisa Tadewalt, an ISA-certified arborist and co-founder of Urban Forest Pro. "It secretes compounds into the soil that inhibit the growth of nearby plants as a protection measure for itself," she says. "If apple trees are growing near a fennel plant, you can expect them to experience slower growth and reduced fruiting." 

Tadewalt recommends growing chives instead of fennel. "They are a natural pest repellent, especially against aphids and apple scab spores," she says. "Their strong scent can also help mask the presence of the apple tree from certain insect pests."

Black Walnut Trees

They may be beautiful and long-lived, but black walnut trees (Juglans nigra) are notoriously unfriendly neighbors in the garden, warns Andy Ferguson, orchardist, farmer, and co-owner of Ferguson's Orchards. Your apple tree might struggle to grow, develop yellowing leaves, have poor fruit production, and even die if it's planted next to a black walnut tree.

"Black walnuts release a chemical called juglone that is toxic to many other plants, including apple trees," Ferguson explains. "It seeps into the soil from the roots and fallen leaves, which can damage or even kill apple trees growing nearby. Even an otherwise healthy apple tree can suddenly start to decline if it's planted within range of a black walnut."

If you have your heart set on having both apple and black walnut trees in your garden, plant them 60 to 80 feet apart. Or better yet, plant a serviceberry tree instead. "It’s native to much of the United States, beautiful in all four seasons, and completely safe to plant near apples," Ferguson says.

Potatoes

Potatoes (Solanum tuberosum) are in a plant group called the nightshade family, and can host blight and other soil-borne diseases that affect apples. "Planting potatoes near apple trees increases the chance of developing fire blight and other fungal infections, especially if the trees are growing in wet conditions," Tadewalt warns. "Plant onions or garlic instead, since these plants usually deter pests and can even help suppress some fungal issues in the soil."

Eastern Red Cedar

Eastern red cedar trees (Juniperus virginiana) and apple trees will develop cedar apple rust if grown together, warns Mason Hanrahan, an ISA-certified arborist and qualified tree risk assessor with Tim-O-Tree. "This fungal infection produces ugly orange spike-like galls on the foliage of both trees and on the fruits of apple trees," he warns.  "It infects flowers, leaves, young shoots—and, most importantly, fruit. Infected fruit sprouts with dozens of orange galls, rendering it inedible."

Unlike wood-decaying fungal infections, cedar apple rust does not require a wound to infect the tree. Spores land on buds or leaves and can infect the plant within hours. "So even if you undertake proper measures to prevent fungal infections more generally, these measures won't help with cedar-apple rust," Hanrahan says. 

In addition to ruining your trees, planting a cedar near an apple tree could also harm your neighbors' trees, since the fungal spores can spread and infect trees even miles away. If you want to plant a privacy hedge, oaks, maples, and even ginkgos are ideal. "They will not blend into a single form the way that cedars can, but they still provide privacy screening," says Hanrahan.

Broccoli

Broccoli, as well as cauliflower, is a heavy feeder that will compete with your apple trees for nitrogen and other nutrients. "If they are planted too close to apple trees, you can expect the tree growth to be slower, especially in younger trees or in soils with marginal fertility," Tadewalt says. Lettuce is a better choice than broccoli (Brassica oleracea) because it has shallow roots and a lower nutrient demand. Plus, lettuce can benefit from the dappled shade a maturing apple tree gives it.

Hawthorn Trees

Hawthorn trees (Crataegus) are highly susceptible to fire blight, a destructive bacterial disease that can be transmitted to nearby apple trees, says Dick Zondag, horticulturist and owner of Jung Seed Company. Fire blight can kill your apple tree blossoms, fruit, and shoots, as well as the entire tree. "The alternatives to these plants are other apple trees for cross-pollination purposes," Zondag suggests, “or other fruit trees that would not have similar diseases."

Sunflowers

Sunflowers (Helianthus annuus) cast significant shade and can compete with young apple trees for moisture and nutrients, Tadewalt warns. “When planted close together, apple trees may become leggy, produce less fruit, or show signs of stress from limited sunlight,” she says. "Other flowers, like calendula or nasturtium, can attract beneficial insects and grow low enough to avoid shading apple trees."