A few family members are looking at planting some nut trees and they were wondering which companion plants would work best. However, they’re concerned about any juglone the nut trees may produce. To help them out, I did some research. Here’s what I found.
For nut trees (including walnuts, pecans, and almonds), the best companion plants are stone fruits, mulberries, pawpaw, raspberries, and grapes. It can be tricky to companion plant with some nut trees as they produce a chemical called juglone. For best results, plant juglone-resistant varieties.
So, while these are some of the companions for nut trees, what are their benefits, and what are some other (juglone-immune) examples? Let’s take a closer look.
Benefits of Companion Planting
Companion planting is selecting specific plants to place together to achieve benefits, such as increasing pollination or repelling pests. Sometimes these benefits are one-sided, while others are mutual.
A famous example is The Three Sisters—planting corn, beans, and squash together. The corn provides a trellis for the beans to climb, the squash provides a ground cover, and the beans fix nitrogen in the soil. Plus, all of them provide food!
Here’s a list of the benefits that gardens gain from companion planting:
- Boost Pollination
- Repel Pests
- Prevent Weeds
- Fix Nitrogen
- Amend the Soil
- Protect the Soil
- Reduce Evaporation
- Provide a Living Trellis
- Maximize Space
- Produce More Food
If you’d like to learn more about the benefits of companion planting, check out my other post: The Top 10 Benefits of Companion Planting.
What Is Juglone and Why Does It Matter?
Feel free to skip this section if you already know about juglone. But if you’re not familiar yet, it may be worth your time to learn more.
Juglone is a chemical produced by the walnut family (including walnuts, hickories, butternuts, and pecans) that suppresses the growth of and even kills other plants. Juglone is produced in these nut trees’ fruits, leaves, branches, and roots (source).
While any member of the walnut family secretes juglone, black walnuts produce the highest amount.
In addition to juglone, competition of sunlight, water, and nutrients can lead to killing other, sensitive plants.
How Far Away Should You Plant From Juglone Trees?
Generally, keep juglone-sensitive plants away from the drip-line of juglone-producing trees. This typically means at least 10-15 feet away from younger trees and at least 50 feet away from the mature trees.
Gardeners who have large walnut trees near their vegetable gardens should consider an alternate site. The greatest concentration of juglone in the soil exists within the dripline of the trees. The dripline is the area between the trunk of the tree and the end of the branches. The toxic zone from a mature tree occurs on average in a 50-foot radius from the trunk. Avoid planting your garden in these areas to protect your garden from damage.Chris Feeley, Extension Forester, Iowa State University
Now, let’s take a look at the top 10 juglone-immune companions for nut trees (and some bonus ones).
1. Stone Fruits
Stone fruits typically include cherries, peaches, nectarines, apricots, and plums. Although, pitted berries and fruits such as blackberries and olives are sometimes included. This is from their classification of being a drupe, or a fruit that surrounds a single, hardened shell with a seed inside.
Compared to apple and pear trees, stone fruits are generally immune to juglone.
Stone fruits assist nut trees by attracting pollinators, shading the soil, holding groundwater, breaking up compact soil, and providing mulch (from their branches and leaves). You can plant stone fruit trees just outside of the drip-line of the nut trees.
Most stone fruits prefer a temperate climate over a tropical one. For example, cherry trees prefer hardiness zones 5-7 (source). However, adjusting their microclimate such as growing in greenhouses will stretch their zones and make it possible to grow in other climates.
Popular companion plants for stone fruits include chives, marigolds, dandelions, wildflowers, comfrey, lavender, rosemary, and sage. Raspberries also make great companion plants for stone fruits and nut trees.
Avoid planting nightshades near stone fruits as some fungal diseases can spread.
Mulberries are deciduous fruiting trees that typically grow 30 to 50 feet tall. They prefer a slightly acidic soil pH of 5.5 to 7.0 and USDA hardiness zones 4-8 (source). Like most fruiting trees, they can take 2-10 years to fruit (depending on if they’re grown from seed or grafted).
When interplanted with nut trees, mulberry trees provide similar benefits to stone fruits, such as groundwater retention, soil health, and mulch.
Their flowers also attract pollinators for nut trees—which generally require cross-pollination (source).
Everbearing mulberries are moderately drought-tolerant and self-fertile. Their fruiting season is typically from June to September. Mulberry fruits drop on their own fairly easily, so a trick that many gardeners use is to place a sheet under the tree to catch the berries as they fall.
You can also interplant mulberries with alliums, marigolds, and nasturtium.
Persimmons are a great companion for nut trees as they grow in similar climates and attract pollinators, break up compact soil, and provide mulch. These fruit trees are also fantastic to have as they have no serious disease or pest problems (source).
The most common varieties grown are American persimmon, Texas persimmon, and Oriental persimmon. Depending on your needs, you may prefer an Oriental persimmon grafted onto an American persimmon rootstock for increased hardiness and resistance to wet soil.
Companion plants for persimmons include mint, borage, comfrey, chives, marigold, and strawberries.
Pawpaws are native to the Eastern US and Canada and have a long history with the indigenous peoples. Their fruits resemble mango and taste like bananas and are often called “a tropical fruit for temperate climates” (source). However, their storability and shipping prove difficult (which explains why we don’t see them in grocery stores).
Because of their tolerance to the more temperate climates of nut trees, they’re a great choice for a companion plant (ideal in zones 5-8). Pawpaws grow 12-25 feet tall and are late-bloomers, so they’re less like to become damaged by a late frost.
They also grow well in partial shade, which means you can interplant them densely with nut trees (even slightly within their canopy). In fact, pawpaws prefer it.
While pawpaws aren’t as drought-tolerant as some of the other companions on this list, they can survive droughts if they’re matured and shaded well.
Pawpaw grows quickly if mulched and watered during droughts; it is drought-sensitive when grown in sun.The University of Kentucky, College of Agriculture, Food and Environment
So, if you’re interested in growing pawpaws in your area, I recommend using a permaculture approach and providing lots of mulch and shade, especially if you’re in a drier region.
Since the afternoon sun is hotter than the morning sun, it’s best to shade the tree from the west side. Some quick ways to create shade are by using an umbrella, shade sails, or other trees.
Keep in mind, like all of the plants on this list, mature pawpaws will need much less water than younger pawpaws.
While blackberries are slightly sensitive to juglone, raspberries (including black raspberries) are immune to it. This, along with increased pollination and the natural barrier of its bramble, makes raspberries a fantastic understory for nut trees.
The bramble can easily be used as a living fence or barrier for unwanted pests or visitors. You can even create a hedge of raspberries on the outside of your fruit trees to protect them while keeping the inside free for you to harvest the fruits.
Common companion plants for berry plants include wildflowers, comfrey, and fruit trees.
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6. Gooseberries (Currants)
Gooseberries are a type of currant and have two main varieties: American and European. American gooseberries are native to the northeastern and northern US, including Canada, and are typically more productive than the European variety. However, the European variety commonly has larger and more flavorful fruits.
American gooseberries are similar in size and taste to grapes, and more grocery stores have recently started carrying them.
When used as an understory companion for nut trees, gooseberry bushes attract pollinators, shade soil, and provide mulch.
Gooseberries generally require little watering once established but need more watering if they’re exposed to the sun in hot and dry weather. For this reason, mulching and composting are vital to reduce evaporation and retain water in the soil. Additionally, providing some afternoon shade will go a long way.
In moisture-retentive soils established bushes need very little additional watering, but regular watering in hot, dry weather is a must for young plants and essential for container-grown gooseberries.Growveg.com
Grapes are fairly easy to grow in Mediterranean climates like California, Spain, and France, which explains why much of the wine industry is based in these areas. Living in California for 10 years, I saw my fair share of vineyards and they really did grow nicely there.
However, grapes also grow well in the more temperate climates of nut trees. American grape varieties, like concords, are more cold-hardy and can be grown in zones 4-8, while European grapes generally prefer warmer climates with zones 7-10 (source).
Grapes are great to use as a vining companion plant for nut trees as they can be used in between other plants or to bridge gaps. They can even vine up the nut tree’s trunk without damaging the tree.
While most grapes don’t need to be cross-pollinated, they attract pollinators—which then also visit the nut trees.
Grapevines also have many permaculture uses such as shading during the summer and letting in sunlight during the winter (when the grapevine’s leaves drop). For example, we have a wooden overhang above our patio where a grapevine grows up and over it as a living trellis cover.
You can even position grapevines to grow up near the western or southern sides of your houses to help passively heat and cool your home’s temperature. Of course, you can use grapes for food and wine.
Some grape companions include alyssum, basil, legumes, chives, clover, blackberries, mustards, geraniums, and oregano. Avoid planting lettuce, cabbage, garlic, and radishes near grapes as they tend to drink up lots of water.
Horseherb is a drought-tolerant, flowering perennial which grows in the same climate as nut trees and makes an amazing living ground cover and pollinator-attractor. It’s super popular in nut groves in Texas and is even used as lawn substitutes.
This plant grows up to 8-10 inches tall and THRIVES in the shade of nut trees.
However, keep in mind that this plant grows with runners (like strawberries and mint), so it can get invasive if not kept in check! Also, avoid planting in any depressions in the land that can get flooded as horseherb doesn’t like wet feet and can rot.
Some companion plants for horseherb include baby blue-eyes, widow tears, false dayflower, violet rueilla, and sedges (source).
Garlic, onions, and chives are all part of the same family (allium) and, no surprise—they’re more potent-smelling than most plants. More specifically, this is likely due to their naturally occurring sulfur, which is great at repelling pests as well as its use as a natural anti-bacterial and fungicide.
In fact, these plants’ scents are so effective that some deterrents are even made from garlic (source).
For pests, plant garlic, chives, and onions near your nut trees to help repel aphids, mites, maggots, as well as rabbits and deer (source). This is because their pungent sulfur smell and taste are not appealing to these pests’ strong senses.
It’s believed that the sulfur from these plants also helps prevent certain plant diseases to some extent. For example, a common companion plant pairing is interplanting chives near apple trees to prevent apple scab (source).
However, if fungal or bacterial diseases do take hold, garlic cloves can also be mixed into organic sprays along with neem oil and applied as a treatment.
Garlic, chives, and onion plants also have shallow roots that typically don’t exceed 12-18″, making them a good companion to plant outside of the nut tree’s canopy.
These three plants all do well in both full sun and partial sun. However, if you’re in a warmer climate, consider planting them on the east side of your nut trees—so the trees help shade them from the hot, afternoon west sun.
Alliums have many companion plants, but avoid planting them with legumes and other alliums.
For more companion plants that repel pests and diseases, visit my other post: 10+ Companion Plants That Prevent Pests and Diseases.
You may be thinking, “How did a weed make this list?”. But what is a weed other than a plant we think we don’t want?
The reason why we see dandelions growing everywhere is that it’s one of the first plants in ecological succession. In other words, it grows because it’s taking advantage of damaged soils, and is trying to improve them. As a result, dandelion roots are great at fixing nitrogen in the soil, similar to comfrey.
Also like comfrey, dandelions naturally protect soil from erosion and extreme temperatures, and generally—are a highly effective mulch.
For all of these reasons, dandelions make a great companion plant for nut trees.
As a bonus, dandelions also have edible leaves and flowers and are commonly made into many homemade products.
To see more companion flowers, check out my other post: The Top 10 Companion Flowers for Gardens, Vegetables, & More.
More Plants That Are Immune to Juglone
Here are some bonus companions for nut trees. If they made this list, they’re immune to juglone. You can also use these plants as a neutral barrier between juglone-producing trees like pecans and walnuts and those that are sensitive to juglone.
|Fruits and Vegetables||Trees||Flowers|
|Lima & Snap bean||Elm||Bergamot|
|Beet||Maple (most)||Morning Glory|
The good news is that juglone does not spread far through the soil. So, using any of the above plants in-between the juglone-producing plants and those that are sensitive often works well.
The largest concentrations of juglone and hydrojuglone (converted to juglone by sensitive plants) occur in the walnut’s buds, nut hulls, and roots. However, leaves and stems do contain a smaller quantity. Juglone is only poorly soluble in water and thus does not move very far in the soil.
Michael N. Dana and B. Rosie Lerner, Department of Horticulture, Purdue University Cooperative Extension Service
What Not To Plant With Nut Trees
Keep the following plants at least 10-15 feet away from smaller juglone-producing trees, and at least 50 feet away from mature juglone-producing trees.
|Fruits and Vegetables||Trees||Flowers|
|Blackberry/Blueberry||Yew||Blue Wild Indigo|
|Pepper||White & Red Pine||Lily|
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