Companion Planting: The Ultimate Guide

Companion planting is growing different crops near one another so that they can help each other grow, keep pests away, and attract beneficial insects that assist in pollination.

Gardening is a wonderful hobby, but there really is a lot to learn before you can feel you’ve ‘got your head around it’. One important issue, which surprisingly can have a big impact on the general health of your garden, is what to plant where and with whom.

Yes, that’s right, who would have thought that plants are social beings too – well sort of. They have relationships with other plants that are either beneficial or harmful. Because plants can’t move – either towards plants they like or away from other plants they don’t like, it is up to us as gardeners to understand and utilize this phenomenon to benefit of all.

This is where the principles of companion planting can assist in making the decisions of what to plant where and with whom in the garden. By following some companion planting guidance, it really can make gardening a lot more straight forward. Everyone needs a blueprint and a plan based on some clear principles, and companion planting can provide help with those principles. It is not just what to plant together, it is also about what not to plant together.

Just like a lot of things in life, including people, some combinations just don’t work that well. Plants are the same. Some combinations don’t work well together and other combinations thrive.

Certain plants have a positive effect on other plants in that they provide nutrients and pest protection to allow faster and healthier growth.

The end result can be more bountiful produce or flowers or even both. Two plants that work with each other can give each other strength to be the best plants that they can be!

Companion Planting In Your Garden

So you want to use companion planting in your garden, but you don’t know where to get started. The concept has been around for a long time which results in lots of different thoughts and ideas on it. There are some companion planting approaches that have simply been passed down through the generations of gardeners. While some of these tried and true combinations may be correct, that isn’t always the case. Recent studies have been able to shed more scientific light on which plants truly are beneficial to others and why that is so.

Understanding the “why” is key to increasing your garden knowledge around this area. You don’t need a science degree in horticulture or have been a gardener all your life to explore the key pieces of knowledge about companion planting. New facts are coming out all the time, and the whole area can get very scientific, but this will get you started on the journey.

Benefits of Companion Gardening

  • The most significant benefit of changing up your gardening strategy to take this area into account is being able to enjoy healthier plants. When you get it right, plants grow more quickly and are more healthy. Healthier plants look better visually and are more disease and pest resistant.
  • The increased pest resistance feature is important. With this approach, you don’t need to spray pesticides or other harmful chemicals. This is because a companion plant can help to mask the scent of its neighbor that the bugs would normally be attracted to. This confuses the bugs so they head off looking for a simpler target.
  • Another benefit is that the food you grow in your garden will tend to taste better when you practice companion planting. When compatible plants are sharing roots and in the soil adjacent to each other, the healthier plant will have a better taste when harvested. Of course, you can have the opposite effect if you plant types together that don’t like each other. Bottom line is that healthy plants taste the best.

The Organic Gardening Approach:

  • If you are keen on growing organically, companion planting is an invaluable approach to keep down the amount of chemicals you use on your plants before you harvest and consume them. It is a key way to protect your plants without using chemicals.
  • Companion planting has never been easier. There are lists that lay out everything for you so there is no guesswork involved. You can use these to re-vamp your garden and make things better than they have ever been before, so get started now!
ApplesComfreyEnriches soil when mulchedGrow several comfrey plants under the apple tree then cut back and mulch periodically.
ApplesYarrowAttracts pollinating insectsPlant yarrow close to apples to attract bees and other pollinating insects
ApplesNasturtiumsDivert pest insects to a trap cropPlanting nasturtiums in close proximity to apples acts to divert pest insects like black aphid away from the apples. Better to have them on the nasturtiums than your apples.
Brassicas, Bokchoy, Broccoli, Brussel Sprouts, Cabbage, Chinese cabbage, Napa cabbage, Cauliflower, Kale, Kohlrabi, Mustard greens, Pak choi, TatsoiNasturtiumsDivert pest insects to a trap cropCompanion planting broccoli or any other brassicas in close proximity with nasturtiums will help keep cabbage white butterflies away by attracting them to the nasturtiums. Once the nasturtium leaves are infested with cabbage works, throw the infested leaves in the compost.
Brassicas, Bokchoy, Broccoli, Brussel Sprouts, Cabbage, Chinese cabbage, Napa cabbage, Cauliflower, Kale, Kohlrabi, Mustard greens, Pak choi, TatsoiChives, Garlic, Leeks, Garlic Leeks, Onions, Shallots, Spring onion, Red onion, Yellow onionDeter pest insectsCompanion planting onions with brassicas is of great assistance to the brassicas due to the assistance all the onion family give in detering pests such as cabbage loopers and cabbage worms.
Broad beansNasturtiumsDivert pest insects to a trap cropPlanting nasturtiums in close proximity to broad beans acts to divert black bean aphids or blackfly to the nasturtiums instead of the broad beans. This way you can identify and deal with the aphids early on the nasturtiums before they move to the broad beans.
DahliasNasturtiumsDivert pest insects to a trap cropPlanting nasturtiums intermingled with dahliias will help to divert black aphids or blackfly to the nasturtiums instead of your lovely flowers. This gives you a chance to identify and swiftly deal with the aphids early on the nasturtiums before they move to more important plants.
PotatoesNasturtiumsDeter pest insectsCompanion planting tomatoes with nasturtiums helps to control potato beetles.
StrawberriesBorageDeter pest insectsCompanion planting strawberries with borage helps keep damaging pest insects away from the strawberries becasue borage deters many pest insects.
TomatoesMarigoldKill soil nematodesCompanion planting tomatoes with marigolds helps to kill damaging root knot nematodes due to beneficial marigold root secretions.
TomatoesBasilDeter pest insectsFor this combination to work to deter whitefly, you really need a lot of basil plants compared to the number of tomato plants. However, if you're invested in a small number of tomato plants, just put lots of basil plants around it and it will help. It won't make much difference for fruit-fly though.

Companion Planting For Potatoes

Companion planting helps you improve the growth of your potatoes, protect them from their natural enemies, and enhance their flavor without having to use chemical fertilizers and pesticides. However, to make it work, you should know which plants are friends of your potatoes and which ones are foes.

What Companion Plants For Potatoes

companion planting for potatoes

Dead nettle (Lamium) may be a weed in many situations and it can become quite invasive, but it is a good friend as far as potatoes are concerned. It helps improves flavor, increases growth and assists in keeping damaging insects away. Another good companion for potatoes is sage, which keeps flea beetles (family Chrysomelidae) at bay. If you want to protect your potatoes from the Colorado potato beetle, plant them near nasturtium, coriander, tansy, or catnip.

Green beans can also repel the Colorado potato beetle. They don’t compete with potatoes for nutrients. On the contrary, they enrich the soil with nitrogen, which enhances the growth of potatoes and keeps them strong. Potatoes return the favor by protecting green beans from the Mexican beetle.

Want your potatoes to taste better? Plant them with cabbage, corn, and beans. They also help them grow better. You can also grow some horseradish on the corners of your potato garden patch. Horseradish makes potatoes more resistant to diseases and enhances their flavor, too. Other plants that you can grow with potatoes are scallions, lettuce, and spinach.

Flower Power

Marigold is a favorite companion plant because it produces natural pesticides. The soil that surrounds a marigold plant can kill nematodes upon contact. It also protects potatoes from viral and bacterial infections. However, marigold isn’t the only flower that can help potatoes.

Alyssum can serve as living mulch for your potatoes and attract predatory wasps that eat harmful insects. Petunias help protect your potatoes from leaf hoppers. If you want to attract insects that feed on harmful bugs, plant some yarrow, parsley, and basil; their flowers attract the beneficial insects. You can also try planting some petunias and amaranth near potatoes.

Plants To Avoid Planting Near Potatoes

While there are plants that help potatoes grow, there are also plants that could possibly harm them. Raspberries, tomatoes, cucumbers, squash, and pumpkins all seem to make potatoes more susceptible to blight. Never plant potatoes in a soil that has been planted with tomatoes, eggplant, and other nightshade vegetables in the last two years. Other plants that you should not plant with potatoes are carrots, asparagus, fennel, atriplex, turnip, onions, and sunflowers.

Companion Planting For Carrots

Companion planting for carrots

In the last blog post, you learned how companion plants help one another grow and protect each other from pests.  Carrot is another plant that can benefit from companion planting.  A popular book called “Carrots Love Tomatoes,” originally published in 1975, is now widely considered as the bible of companion planting.  The author of this book, Louise Riotte, wrote that carrots and tomatoes share a mutually beneficial relationship in the garden.

Carrot’s Best Pal: It Ain’t Peas

Tomatoes provide shade for the heat-sensitive carrots.  Tomatoes also secrete a natural insect deterrent called solanine which kills insects that could otherwise harm carrots.  They can enhance the flavor of carrots, too.  Carrots, on the other hand, break up the soil so that more air and water can go to the tomato plants’ roots.  There’s one thing to keep in mind if you plan to grow carrots and tomatoes together.  Tomatoes can stunt the growth of carrots so make sure that you plant them at least 15 inches apart from each other.

Knights in Shining Armor: Carrot Defenders

Besides tomatoes, there are plants that can help protect carrots.  Carrots and leeks make good neighbors.  Carrots are often attacked by carrot flies.  Leeks are susceptible to leek moth and onion fly infestations.  When leeks and carrots are planted together, their scents act as repellents of each others pests. Onions mask the odor of carrots, confusing carrot flies and keeping them uninterested.  Rosemary and sage also repel carrot flies, as do chives, which improve the flavor of carrots. Flax produces oil that protects carrots from pests.

There are a couple of things you need to remember if you want to use companion planting to protect your plants from pests.  First, it is important protective plants need to mature before they can effectively keep pests at bay. For instance, marigold needs to be grown at least one season before it can protect plants from nematodes.  Also, certain plants can weaken the protective ability of other plants.  This underscores the importance of knowing which plants should be grown together.

Other Compatible Plants

You may plant carrots near beans.  Carrots are said to help beans grow, but know that it’s almost a case of unrequited love.  Beans fix nitrogen in the soil, but carrots don’t need a lot of nitrogen, so beans do very little to help carrots.

Carrots and radishes can be planted at the same time.  The radish seeds will germinate ahead of the carrots seeds, loosening the soil for germinating carrots.  The carrots will still be young when the radishes are ready for harvesting.  When the radishes are harvested, there will be more room for carrots to grow.

Lettuce and other plants that belong to the cabbage family are also beneficial to carrots.  Amaranth loosens the soil, making it easier for carrot roots to burrow through the soil.  Marigold, parsley, and nasturtium are good companions as well.

No Love Lost: Plants That Carrots Would Rather Stay Away From

Carrots hate coriander and dill.  Both plants have root excretions that are harmful to carrots.  Parsnips and carrots are both vulnerable to carrot flies and to the same soil-borne diseases, so it’s best to plant them away from each other.

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