Companion Planting

One of the most important considerations when companion planting is how much water the plants need. Most fruit and vegetable plants like moist soil. Basil is an example of a plant that thrives in moist soil. You could plant Basil next to your Tomatoes which also likes moist soil or next to Cilantro which, you guessed it, also wants moist soil. But you wouldn’t want to plant Basil immediately next to Rosemary which prefers to have its soil dry out a bit. You want to water your garden beds evenly so all of the soil in the bed receives the same amount of moisture. You cannot control how far the moisture spreads in the soil or how far out a plant’s roots might spread. If you have plants with different water needs in the same garden bed, chances are some plants will experience root rot from overwatering, or conversely, some plants will wilt from lack of proper moisture levels.

Light is another crucial consideration for companion planting.  Charting how the sun beams on your garden at different times of the day and during different times of the year (when the day length is longer or shorter) is hugely beneficial for every gardener. Chances are that some parts of your garden will receive more sun than others. You may even have a garden bed that receives more sun on one side than the other. Aim to plant crops with similar light requirements together, but take into consideration changes in light throughout the day or even the season if you anticipate growing crops with lifespans that extend over multiple seasons. There’s no reason to avoid growing a sun-loving plant next to a shade-tolerant one if that part of your garden bed receives a little less sun than the rest of the bed.

Space is an obvious consideration. Every seed packet lists suggested spacing between plants to allow enough room for them to grow. However, you’ll also want to account for plant heights when thinking about which plants can live in harmony together. Shorter plants should be placed in front of taller plants so that sunlight is not blocked from reaching them. Although, plants that are more sensitive to hot temperatures could happily grow at the base of taller plants that help to shade them from the hottest temperatures of the day. Consider the roots of your plants as well. Plants with shallow root systems may grow well next to plants with extensive root systems as the roots of each plant will generally occupy different layers of the soil. Root crops such as carrots and beets may not grow well next to plants with extensive root systems that have a wide spread, such as squash, as the squash roots may interfere with the growth of the carrots and beets.

Temperature is less of an obvious consideration for companion planting but nevertheless a crucial one.  As stated above, if you have plants that are not tolerant of your summer heats, you may choose to grow taller plants neighboring them to provide some shade as relief from the heat. If you’re an extreme gardener like me growing crops year round, temperature is a crucial consideration for helping your plants survive the frigid winter temperatures. Alliums such as garlic, onions, and shallots are often grown in the fall.  Hardneck garlic can generally weather temperatures as low as -30°F.  Whereas softneck garlic, shallots, and onions may generally only tolerate temperatures down to around 20°F. If you live in a climate where temperatures typically fall below 20°F, growing softneck garlic, shallots, or onions can still be possible with cold frames or row covers, but planting hardneck garlic in those same cold frames or row covers may not be the best idea.

Plants of the same family can suffer from the same diseases. For this reason, although many times plants in the same family have similar requirements and would appear suitable for companion planting, such as tomatoes and peppers, it may be advisable to put space between those plants. Some diseases like blight can live in the soil for years after it strikes your crops. This is where crop rotation can be an important consideration for companion planting.  Even if a plant meets all the other requirements for the garden bed you’d like to grow it in, it may not be the best idea if you’ve recently grown a plant of the same family in that bed.

Harvest is generally not a large concern for companion planting, but nevertheless worthy of mention. Many plants are harvestable above ground and do not interfere with other plants. But root crops do need to be pulled from the ground. Depending upon the plant, harvest can cause quite a disturbance to the soil, especially in the case of potatoes. It may not be advisable to plant potatoes next to a plant that would be harmed by root disturbance such as lettuce, which has quite shallow roots. Another consideration for harvest is timing. Many crops are planted out in the Spring and harvested over the summer and into early Fall. Other crops, such as garlic is usually planted in mid-to-late fall, but not harvested until the following July. While you may not have many other plants still growing at the time you plant garlic, you will want to carefully consider the placement of your garlic as it will impact the growing space you have the following Spring and Summer.

As stated at the outset of this article, claims that companion planting will deter pests from other plants are generally unfounded and not backed by scientific study. Nevertheless, pests can be an important consideration for companion planting. Brassicas can be decimated by the cabbage worm. Planting broccoli, cauliflower, and cabbage in the same garden beds protected by netting can be beneficial in protecting your harvests.  Conversely, if you plant all of your brassica together unprotected, they could all be decimated by the cabbage worm. In that case, you may want to spread out your brassica plantings around the garden so even if the cabbage worm found some of them, it may not spoil your entire harvest.

Here at Love our One, we keep nutrients simple by only adding natural composted and compostable materials to our garden beds. Generally, we treat our garden beds equally in terms of adding nutrients back into our living soil. Nevertheless, a consideration of companion planting would be to interplant heavy feeder crops with less nutrient-demanding plants so as to not deplete the nutrients faster than they can be added back in because we don’t use commercial fertilizers throughout the growing season.