Turnips are grown both for their green leaves and for the starchy swelling above the roots. Both the greens and roots are vulnerable to pests. Here are some good companion plants that turnips will grow well with, and some that you should not plant them nearby.
Why Do Turnips Need Companion Plants?
Here are some of the ways companion plants work with turnips.
Aromatic plants like mint, garlic, nasturtiums, catnip, thyme, rosemary, and lavender mask the scent of turnips and make it hard for pests to find them. Radishes also repel pests that bother turnips.
Bring Pest Predators
In addition, many of these aromatic plants attract beneficial insects that eat pests that do find the turnips.
Beans and vetch fix nitrogen from the air. They fix more nitrogen than they need and then excrete the rest into the soil and make it available to turnips. The nitrogen improves the crop of turnips.
Vetch and some thymes act as a living mulch to stabilize soil moisture and temperature and keep weeds away from turnips.
Benefit from Turnips
Turnips benefit other crops planted near it, such as Brassicas, by attracting insects to the turnip plants. It acts as a trap crop. This is hard on the turnips but benefits the other Brassicas (turnips are a Brassica).
You can read more about companion plants in general in my article, “Companion Planting – Everything You Need to Know.”
Top 15 Best Companion Plants for Turnips
Here are the top fifteen companion plants for turnips and what they do when grown with turnips.
Mint repels flea beetles and aphids that would otherwise attack your turnips. Mint also attracts pest predators that will eat any pests on the turnips. Because mint is very invasive, do not put it in the ground or it will outcompete the turnips. Instead, put pots of mint in the space between the rows of turnips to protect them.
Turnips act as a trap crop to keep slugs, snails, aphids, and other pests from eating your Brassicas. To use turnips as a trap crop, plant them at the head of the row for three or four feet, then plant the Brassicas. When the turnips are full of bugs, treat them with an appropriate pesticide or remove them so the pests don’t spread to the Brassicas when the turnips are eaten.
Garlic deters aphids, onion flies, and beetles from attacking turnips. Turnips deter borers that target garlic. Interplant garlic and turnips in the same row for the most benefits from each other.
Beans fix nitrogen from the air. The nitrogen that beans don’t need is excreted in the soil where turnips can reach it. Plant turnips in a border around your beans or interplant them in the same row.
Nasturtiums repel aphids, cabbage worms, and other pests that eat turnips. In addition, nasturtiums attract ladybugs and hoverflies, which eat pests on turnips. Plant nasturtiums as a border around your turnips, in the space between rows of turnips, or intersperse them amongst the turnips.
Catnip is in the Mint family. It repels aphids and flea beetles that would attack the turnip plants. In addition, catnip draws pest predators that will eat any pests that do make it to the turnips. Catnip can be invasive, so put pots of it out in the garden near turnips. If you have a lot of outside cats in your area, tent chicken wire over the catnip to keep the cats from bothering it.
Thyme has a strong scent that repels pests like the cabbage whitefly that eat turnips. In addition, thyme draws pest predators that eat the pests on turnips. Finally, thyme draws pollinators that benefit the entire garden. Thyme may repel rabbits and deer if planted in the same row as turnips or in the space between rows of turnips. Low-growing types of thyme can be used as a living mulch around turnips.
Vetch protects turnips from aphids. Vetch fixes nitrogen from the air and puts it in the soil where turnips can reach it. The vetch also acts as a living mulch, stabilizing soil moisture and keeping weeds out of the garden. Finally, it attracts pest predators that will eat pests on the turnips. Plant the vetch in the space between the rows of turnips or as a border around the turnip rows.
Radishes repel cucumber beetles, squash bugs, squash vine borers, aphids, and other pests from turnips. Plant radishes between rows of turnips, or as a border around the turnips. Since radishes grow so quickly, you may need to plant them every three weeks or so to make sure they last until the turnips are ready to harvest.
Dill is another aromatic that repels pests from the plants around it. The scent confuses pests searching for turnips. Plant it as a border around turnips or in the space between rows of turnips for the best results.
Chives, like garlic, repel pests that will eat turnips. Plant the chives in a border around the turnips to confuse pests and keep them away from the turnips.
The strong scent of rosemary will deter a host of pests. Turnips will attract aphids away from rosemary. Rosemary can grow into a small shrub, so make sure you plant the turnips far enough away that they do not get blocked from the sunlight.
Lavender not only deters insect pests, but deer do not like the scent. If you have a problem with deer in your garden, plant lavender as a border around the whole garden or just use it around particularly tasty crops like turnips.
Celery deters cabbage moths that will eat turnips. Turnips deter aphids from attacking the celery by trapping them on the turnips. Grow them interspersed in the same row for best results.
Marigolds repel pests from turnips and other crops around them. Marigolds also attract pest predators that will eat pests on the turnips. Finally, marigolds will attract pollinators to benefit the whole garden. If you till the marigold plants into the soil after they die, the marigold plants will deter root-knot nematodes. Plant marigolds in the row with the turnips, as a border around the rows of turnips, or between the rows.
Top 7 Worst Companion Plants for Turnips
There are some plants that do not make good companion plants for turnips. Here are seven of the worst ones.
Because potatoes also have large starchy parts underground, potatoes and turnips get in each other’s way when growing. Do not plant turnips and potatoes together or neither will have enough space to grow.
Horseradish and turnips share similar pests. If you plant them near each other, then when the turnips are harvested, the pests will just move over to the horseradish and eat it. Separate the turnips and horseradish with an aromatic plant that will be a barrier to pests.
Like potatoes and turnips, beets have a starchy swollen part that will get in the way of the turnip plants. Do not plant the beets and turnips next to each other but separate them into different rows.
Mustard attracts pests that also target turnips. If you plant mustard near your turnips, the pests will spread to the turnips and damage them. Separate mustard and turnips with an aromatic plant like thyme to disguise the scent of the turnips and confuse the pests that seek them.
Peas and turnips have been shown by research to inhibit each other’s growth. If you plant the turnips too near the peas, neither will grow properly. Separate them by at least six feet for the best results. Do not plant turnips where pea plants have been tilled under or the same problem will happen.
Fennel produces a biochemical that inhibits the growth of any plant near it, including turnips. Plant fennel by itself in the garden because it doesn’t make a good companion for any plant.
Black Walnut Trees
Black walnut trees, like fennel, produce a chemical that inhibits other plants. The chemical black walnut produces is so strong that it lasts in the soil for a long time after the black walnut tree is gone. Do not plant turnips near a black walnut tree or where one has been.
In conclusion, turnips benefit from aromatic plants that mask the scent of the turnips and confuse pests trying to eat the turnips. Beans and vetch benefit turnips by making more nitrogen available in the soil. Turnips benefit other Brassicas by acting as a trap crop for aphids, slugs, and other pests. The fifteen best companion plants for turnips are mint, Brassicas, garlic, beans, nasturtiums, catnip, thyme, vetch, radishes, dill, chives, rosemary, lavender, celery, and marigolds. Bad companions compete for space. They may also share pests with turnips. Some bad companion plants keep turnips from growing near them. The seven worst companion plants for turnips are fennel, peas, potatoes, horseradish, beets, black walnut trees, and mustard.