What not to plant next to citrus trees comes down to four main groups. Skip walnut trees, turf grass, tomatoes, and other heavy feeders inside the drip line of your tree.
These four classes of plants steal water, food, or both from your citrus roots. The right citrus companion planting plan keeps the soil under your tree clean and open instead.
I tested bad companions for citrus by accident a few years back. I planted four tomato plants three feet from my young grapefruit to use the warm sunny spot for summer crops.
The tomatoes took off and grew big and tall by July. The grapefruit pushed almost no new growth that whole season and looked sad and stunted by fall.
I pulled the tomatoes out the next spring and the grapefruit doubled its canopy size in one summer. Two years of stunted growth from one bad neighbor choice taught me a hard lesson.
Citrus has surface feeder roots that spread out wide just below the soil top layer. Anything planted on top of that root zone fights the tree for water and food every day of the year.
Heavy feeders like tomatoes, potatoes, and corn pull nitrogen out of the soil faster than your tree can replace it. They also share soil diseases that hop right over to citrus roots.
Walnut Trees
- Why bad: Black walnut roots release a chemical called juglone that poisons citrus and many other fruit trees nearby.
- Safe distance: Keep citrus at least 50 feet (15 meters) from any walnut tree on your property line or yard.
- Symptoms: Wilting leaves, slow growth, and dead branches show up within one growing season near walnut roots.
Turf Grass
- Why bad: Grass forms a dense root mat in the top 4 inches (10 cm) of soil that blocks water from reaching tree roots.
- Safe distance: Keep grass at least 3 feet (0.9 meters) from the trunk, even more for mature trees with wider canopies.
- Better option: Use a thick wood chip mulch ring instead of grass under the whole drip line of the tree.
Tomatoes and Potatoes
- Why bad: These nightshade crops carry soil borne fungi like verticillium wilt that can jump to citrus roots.
- Safe distance: Plant them at least 10 feet (3 meters) from the trunk and outside the full drip line of the tree.
- Heavy feeders: They also pull massive amounts of nitrogen from the soil in a single growing season.
What can you plant near citrus then? Low growing herbs, legumes, and small rooted flowers all work fine as long as you space them out a bit.
Good plants for citrus companion planting include nasturtium and comfrey. Basil and clover also work well in the drip line of your tree.
These plants fix nitrogen, repel pests, or pull up deep minerals for free. You get a bonus crop and a better tree from the same patch of ground.
Comfrey is my favorite pick for the drip line edge of any home tree. The deep tap root pulls potassium up from below and dropped leaves break down into a free mulch by fall.
I planted three comfrey crowns at the drip line of my Valencia orange four years ago. The tree puts on 15% more growth each year and the soil stays soft and rich without any extra work.
Your spacing rules are simple to follow at home. Keep grass back 3 feet (0.9 m), heavy feeders back 10 feet (3 m), and walnut trees back 50 feet (15 m) from your citrus trunk.
Mulch the whole drip line with 3 inches (7.6 cm) of wood chips instead of plants. Pull the mulch back from the trunk by a hand width so the bark stays dry.
Your action plan starts with a quick walk around your tree. Pull out any heavy feeders inside the drip line, edge back the lawn by three feet, and lay down a fresh mulch ring this weekend.
When I first moved into my current home, I learned that the prior owners had planted a black walnut just 40 feet from a Meyer lemon. The lemon was on its last legs and lost most leaves within one year of my move in date.
Read the full article: Citrus Tree Care: Complete Guide
