Companion planting is one strategy out of many to effectively grow different kinds of fruits and vegetables simultaneously. In essence, companion planting is getting back to the “natural characteristics” of plants and evaluating “plant to plant compatibility” based on history, observed practices, and scientific relationships.
As the theory goes, companion planting is an evaluation of two criteria: (1) neighboring plants that benefit one another and enhance growth rate and yield for each other, and (2) neighboring plants that suppress one another and limit growth rate and yield for each other.
For example, plants (and especially fruits and vegetables) produce and release an array of natural chemicals from their flowers, roots, and leaves. When these chemicals are released, they either favor their neighboring plants and encourage growth, or they oppose their neighboring plants and hinder growth.
Additionally, some chemicals released may either attract or repel certain kinds of pests and insects (although this is less of a worry if growing indoors), making plant combinations extremely important to assess during certain seasons.
Companion Planting Chart
| Vegetable | Companion Plant(s) | What’s Incompatible |
|---|---|---|
| Asparagus | Parsley, Tomato, Basil | – |
| Beans | Almost All Herbs and Vegetables | – |
| Bush Beans | Irish Potato, Corn, Celery, Cucumber, Summer Savory | Onion |
| Pole Beans | Radish, Corn, Summer Savoury | Beets, Sunflower, Onion, Kohlrabi |
| Cabbage family (to include broccoli and cauliflower) | Celery, Onion family, Beets, Aromatic Herbs, Camomile, Chard, Spinach | Pole Beans, Strawberries, Tomato, Dill |
| Carrots | Lettuce, Tomato, Rosemary, Onion Family, English Pea, Sage | Dill |
| Celery | Bush Beans, Tomato, Onion family, Cabbage family, Nasturtium | – |
| Corn | English Pea, Cucumber, Pumpkin, Squash, Irish Potato, Beans | Tomato |
| Cucumber | Corn, English Pea, Beans, Radish, Sunflowers | Aromatic Herbs, Irish Potato |
| Eggplant | Marigold, Beans | – |
| Lettuce | Radish, Strawberry, Carrot, Cucumber | – |
| Onion Family | Carrot, Cabbage Family, Beets, Lettuce, Summer Savoury | English Pea, Beans |
| Parsley | Asparagus, Tomato | – |
| English Peas | Radish, Turnip, Carrots, Corn, Cucumber, Beans | Potato, Onion Family |
| Radish | Nasturtium, English Pea, Cucumber, Lettuce | Hyssop |
| Spinach | Fava Bean, Strawberry | – |
| Squash | Marigold, Nasturtium, Corn | Potato |
| Tomato | Carrot, Cucumber, Parsley, Basil, Asparagus, Nasturtium, Marigold, Onion Family | Fennel, Cabbage Family, Potato |
| Turnip | English Pea | Potato |
Understanding Plant Families
Bean Family (Fabaceae or Leguminosae)
- Anasazi Bean
- Asparagus Pea
- Azuki Bean
- Black Bean
- Broad Bean
- Chickpea
- Cowpea
- Flageolet Bean
- French Bean
- Garden Pea
- Grass Pea
- Haricot Bean
- Kidney Bean
- Lima Bean
- Lupini Bean
- Marrowfat Pea
- Mung Bean
- Nuna Bean
- Pigeon Pea
- Pink Bean
- Pinto Bean
- Runner Bean
- Snap Pea
- Snow Pea
- Soya Bean
- Split Pea
- Tepary Bean
- Urad Bean
Beetroot Family (Chenopodioideae)
- Beetroot
- Chard
- Good King Henry
- Quinoa
- Spinach
- Strawberry Spinach
- Tree Spinach
Cabbage Family (Brassicaceae or Cruciferae)
- Broccoli
- Brussel Sprouts
- Cabbage
- Cauliflower
- Chinese Cabbage
- Kale
- Kohlrabi
- Land Cress
- Watercress
- Napa Cabbage
- Pak Choi
- Radish
- Rapini
- Sea Kale
- Swede
- Turnips
Carrot Family (Umbelliferae)
- Dill
- Chervil
- Angelica
- Celery
- Celeriac
- Arracacha
- Caraway
- Gotu Kola (Pennywort)
- Coriander
- Carrot
- Fennel
- Cicely
- Parsnip
- Parsley
- Anise
- Lovage
Daisy Family (Asteraceae or Compositae)
- Burdock
- Cardoon
- Chickory
- Endive
- Globe Artichoke
- Jerusalem Artichoke
- Lettuce
- Rampion
- Salsify
- Scorzonera
Melon Family (Cucurbitaceae)
- Caigua
- Cucumber
- Courgette
- Gherkin
- Gourd
- Marrow
- Melon
- Pumpkin
- Squash
Onion Family (Alliaceae)
- Bulb Onions
- Chives
- Elephant Garlic
- Field Garlic
- French Shallots
- Garlic
- Garlic Chives
- Kurrat
- Leeks
- Pearl Onion
- Potato Onion
- Rakkyo
- Ramsons
- Shallots
- Tree Onion
- Welsh Onion
- Wild Garlic
- Wild Onion
Potato Family (Solanaceae)
- Aubergines
- Peppers
- Potatoes
- Sweet Potatoes
- Tomatoes
Miscellaneous
- Asparagus
- Corn
- Corn Salad
- Lambs Lettuce
- Miners Lettuce
- Mushroom
- New Zealand Spinach
- Okra
- Pursiane
- Phacolia
- Rhubarb
- Sweet Corn
Companion Planting Considerations for Aquaponics and Hydroponics
Finding the best companion plants in aquaponics and hydroponics is truly a trial and error process and largely depends on your wants, needs, ability, and goals. As a beginner, rule out what’s incompatible first (using the chart above) and then start experimenting with combinations.
Outdoors vs Indoors
First and foremost, companion planting is more of a factor if you’re growing your plants outside in the elements. If you’re growing indoors in a controlled environment, then certain issues can be avoided as a group (pests, insects, plant competitiveness), making companion planting less relevant.
Separation and Spacing
Remember that separation and spacing are everything in companion planting. If you’re having issues with a particular combination of plants, try spacing them out further or separating them into groups. There’s no reason why you can’t put some additional space or section off incompatible plants within the same system.
Water Quality Parameters
You’re five basic parameters — pH, Temperature, Oxygen, Alkalinity, and Nitrogen — need to be considered. Plants that have similar needs — such as ones that share a particular temperature range — should be grouped together whenever possible.
Nutrient Requirements
Nutrient needs are important to think about when picking your companion plants. Because some plants have higher nutritional demands — such as tomatoes — they need to be paired with plants that have similar nutrient requirements.
Matching Fish and Plants
If you’re growing aquaponically, remember that it’s all about balance. Finding the right combination of fish and plants is extremely important so stick to plant combinations that have already been proven to work well with certain kinds of fish. For example, lettuce and peppers might be compatible with one another, but peppers require more nutrients, making them better suited for established and well-stocked aquaponic systems (aquaponic systems become more reliable over time).
Trial and Error Process
Just because someone said it can’t be done, doesn’t mean it’s completely true. Do your own experimentation and grow your own combinations to see which one works best in your particular setup. As stated above, finding the best combination really depends on your wants, goals, needs, and ability. Be open to making mistakes and perfect the process as you go.