Companion Planting and Intercropping
Example of Aquaponics Companion Planting and Intercropping
By Amanda Kanehl, Vegetable Production Manager, May 1, 2024
INTRODUCTION
The time is now! Here in central Iowa our last frost date is about May 10th, but of course mother nature has the final say. Everyone, probably yourself, is gnawing at the bit to get your plants in. I had a close friend ask three weeks ago if she could plant her tomatoes, knowing full well that the nights were still cold enough to stress, damage, and possibly kill the new plants she worked so hard to prepare for a successful season.
Better to use this energy to research and plan on what else to plant with your vegetables, and how to utilize that space to the max. Companion planting, also called intercropping, is something we use as much as possible on our farm and religiously in our greenhouse.
While you’re planning that, why not read up on the difference between cold and warm crops so you can extend your season and get a head start on the next season? Some plants can withstand temps below freezing, some can be overwintered, and some don’t do well in temperatures under 40 degrees. It’s all here in this month’s article.
COMPANION PLANTING VS INTERCROPPING
Intercropping is more about making use of as much space as possible in your planting area while companion planting is more about planting different crops together for a beneficial impact. Both are extremely useful tools for gardeners. We focus mostly on deterrents (plants that pests avoid or that they don’t like), trap crops (plants that are appealing to different pests and can be treated more often than others), and pollinator plants (plants that bring in the pollinators). When there doesn't happen to be a good match, we plant multiple families of vegetables to make use of the space, from the root zone to the tops of the plant.
There is a lot of companion planting information on the internet, some of it is very useful, and some of it has not held true in my experience. This article should provide you with a simple guide to get you started with companion planting based more on our farm’s experience and less on all the varying information that can be found on the web. One of the good companion planting guides comes out of The Old Farmer’s Almanac, and I personally reference it to refresh my memory and experiment with new things in the greenhouse and garden.
PLANT FAMILIES
There are a few families of vegetables that I love to put together in all situations in the greenhouse. But to know which vegetables to put together, you need to know what family they are in. Here's a quick lesson:
● Alliums-
o Onions, Garlic, Leeks, Chives, and Shallots. They have shallow, spreading roots, and are a fairly dependable deterrent with minimal pests.
● Amaranthaceae-
o Beets, Spinach, Swiss Chard. They have the habit of sending one long root with finer roots going off the sides, making them perfect for interplanting, but are loved by many pests.
● Apiaceae-
o Carrots, Celery, Fennel, Parsnip, Parsley, Cilantro, and Dill. These tend to have a single thick root with fine tops. We don’t mind planting these as “fences” to confuse pests in the greenhouse and are great for intercropping to save on space.
● Asteraceae-
o Artichoke, Lettuce, Sunflower, Dandelion, Chicory. Another taproot plant that is loved by many pests.
● Brassicaceae (Brassica)-
o Boy Choy, Broccoli, Brussel Sprouts, Arugula, Cabbage, Collard Greens, Nasturtium, Radish, Horseradish, Kale, Kohlrabi, Mustard, and Turnip. Their roots are shallow but vigorous and varied in their habit, and so require proper space to grow correctly. They are also loved by many pests, especially cabbage loopers.
● Cucurbitaceae-
o Melons, Cucumber, Squash, and Zucchini. Roots tend to be fairly deep and spreading. They have many pests also, especially cucumber beetles and squash borers.
● Fabaceae (Legume)-
o Beans, Peas, Peanuts, and Clover. These famous nitrogen fixers vary in their rooting and growth habits, and so are a great way to use up space in the garden. Pests like these as well.
● Lamiaceae (Mint)-
o Mint, Basil, Oregano, Lavender, Thyme and Rosemary. These strong scented herbs are used as deterrents in our greenhouse. Many are perennials in our zone, mint being an invasive one.
● Solanaceae (Nightshade)-
o Tomatoes, Eggplant, Peppers, and Potatoes. They have a vigorous rooting system, with seedlings being more tap-like than cuttings. They have many pests as well.
Now that you know the families, and their rooting habits, this companion planting thing will be super easy.
GROWERS CHOICES
While we are always experimenting to see what really works and what doesn’t, I do have a few personal favorites. Keep in mind that in our greenhouse we have flooding media beds that are about 4ft wide by 6 ft long and about a foot high. We have to utilize as much of this space as possible in order to get the best bang for our buck year-round. We also have hanging pots to help us grow vertical, we also intercrop them as well as much as possible. Here are a few of my favorites:
Alliums-
Alliums grow well with so many different vegetables, have shallow roots, and don’t use up very much room. While there are so many more uses of these plants, these are the only ones we have tried and swear by as a deterrent and space filler at the moment. Soon we will be trying planting them with our carrots, beets and brassicas.
One of the ways we make use of all the space in our media beds with tomatoes is by planting the tomatoes around the sides, trellising them up, and planting bunching onions in the center. Not only does this cover almost every inch of the inside of the bed, the also deter aphids and other pests away from our tomatoes and to other more irresistible crops like brassicas cucurbits and nightshades.
We also love planting garlic cloves in our raft beds. Not only as a deterrent, but also as a way to expand our selection of sellable vegetables by turning those cloves into garlic greens, and spring garlic in the spring.
Lamiaceae (Mint)-
The mint family has so many uses; many have no pests, some are hardy perennials, all of them flower and attract pollinators, and they all can be used as deterrents. While they can get very big and bushy, they can make attractive centerpieces, or row ends and splits that make the beginning and ends of different species and varieties in a row.
My absolute favorite for companion planting in greenhouse is lavender. The scent is so strong not even spiders want to make their homes in them. Their bushy thick growth habit shades out many weeds trying to sprout in the media beds as well.
Basil is another favorite, not only because of its beauty, but also because it helps deter thrips and whitefly. It has been said to improve the taste of tomatoes and peppers as well, on top of being a very versatile food.
Nasturtium-
Nasturtium is one of those plants that is all around cool. It is a vining, flowering plant that has edible flowers and leaves. They are also a great trap crop, as they are in the brassica family and aphids, whitefly, and cabbage looper are attracted to them. They don’t mind the shade and so can be planted very close to other crops, using them as supports to grow.
Radish and Carrots-
Interplanting Radishes and Carrots is one of my favorite things to do in the garden now. One row carrot, one row radish and repeat. The radishes grow much faster than the carrots and only take up a small amount of space of the surface to bulb. By the time the radishes are ready to harvest, the carrots will be popping up leaves and can be thinned. the room left in between makes it easy to loosen the soil with a shovel without damaging any carrots.
There are many more things for us to experiment and try here in our greenhouse and on our farm, but the use of alliums is a great deterrent in our experience. The mint family also serves as a wonderful pollinator plant on top of being a natural deterrent. Squash plants seem to attract pollinators, as we often find bees sleeping peacefully in them in the mornings and buzzing around during harvest. Be sure to experiment with others and keep notes of what works and what doesn’t!
COLD VS WARM CROPS
To make the most out of the growing season, its beneficial to know about which crops are best grown in the colder months and which in the heat. Depending on what mother nature throws at us, the season can be extended by a few months. Some crops can even be overwintered if treated well.
Most of the cold crops are in the Brassica family. Kales, cabbages, broccoli and cauliflowers, and radishes all thrive in cool weather and struggle in the heat. These can survive temperatures below freezing and a light frost.
Plants in the Apiaceae family, or the carrot family, can overwinter in the soil after the tops die off. This can actually make them much sweeter than raised in the warmer months. When the soil and temperatures become warm enough in the spring they will begin to sprout tops again. They can be harvested anytime once the soil is thawed.
Alliums can also survive extremely low temperatures if planted correctly. While the tops may die off, the bulbs themselves can over winter and begin growing again in the spring.
Amaranthaceae family members, like beets and Swiss chard, thrive in cold weather as well. While these are more heat tolerant than other families, they do struggle a bit in hot weather.
Crops in the Asteraceae family, like lettuce and artichoke, are also cold loving plants that struggle in extreme heat.
Don’t be confused, if a hard wet freeze were to hit any of these plants, they would be damaged, possibly killed, but it can be fairly easy to protect them from this. a light layer of fabric, and/or plastic can be enough to keep temperatures 5 to 10 degrees warmer than the outside air, and also keep the frost off the leaves. In our high tunnel, we use a fabric layer, then a thick plastic over wire hoops to keep the leaves from touching the covering. This helps us grow even in the dead of winter (with an extra layer of protection from the high tunnel).
Cucurbits and nightshades are notorious warm crops on the other hand. They suffer when temperatures get below 45 degrees and can die off when temperatures dip below freezing. Their fruits are the same but also prone to sunscald, which makes part of the fruits die off and go bad. It is important to have proper shading of the fruits during the growing season, which is usually accomplished by the plant’s leaves without issue.
CONCLUSION
Planning your garden is one of the most important parts of being a gardener, and here you have a few more tools to keep in your toolbox. Interplanting and companion planting are great ways to make use of all the precious space in your production area. Knowing what families and crops thrive at which parts of the year can extend your season by two months or more, possibly even store some foods in the soil till the next season.
Don’t forget to take notes on what works, what doesn’t, and what spacing and companions you are using. Don’t be discouraged if something doesn’t work for you, or if it doesn’t work in general. Many of the companion plants you find on the internet are not fool proof and don’t always work depending on the pest pressure you may have. If you fail try again, that’s how we grow!