We didn't have time to talk about Companion Planting at our last Permaculture get together at LuLuland last Sunday, so I thought I would organize my thoughts about companion planting and beyond and share them with you here. Janis
Companion planting is one of those subjects which seems to inspire the creation of charts and illustrations, many of them very artistic and beautiful. Just Google “Companion Planting Images” and a vast array is at your fingertips. Some are better than others, just like the information they contain. Many of them are commercial ventures for you to buy and display on your wall.
Many companion planting charts don’t necessarily apply to the North Florida area. A directive not to plant broccoli and tomatoes together (who knows why) can be ignored because we don’t grow them during the same season. And “who knows why” is another problem with charts. If it’s worth investing the time and effort to put certain plants together, and to avoid combining others, I want to know why.
Some companion planting information has a logical basis--tall plants near plants which need a little shade, plants with similar cultures planted together, etc. If you plan to save seeds, the "do not combine directives" may also make sense. Squash, cucumbers, and melons are in the same family, and may cross pollinate, with unpredictable results from saved seeds. But if you are seed saving, you would not want to plant different varieties of the same species within pollinating distance without doing pollination management of some type for the same reason—but seed saving is another topic, not addressed here.
My concern with companion planting charts and “rules” is that they are mostly anecdotal, with a shortage of scientific evidence to support the directives that are less intuitive or logical. Some sources say that carrot roots are stunted when planted near tomatoes. Is it because of the tomatoes or some other cause? Does it happen consistently? Do carrots planted in the same place without tomatoes nearby have normal roots, etc. Many other sources say Carrots love Tomatoes. I grow carrots in the winter and tomatoes in the summer so it's irrelevant whether they like each other or not. Many of the companion planting rules may be correct, but there are too many unanswered questions for me. See an article from the Puyallup Research and Extension Center at Washington State University and check out the website maintained by the authoring professor, and her link to Gardening Myths. Also view the U of F IFAS site on Companion Planting. The link on allelopathy or discouraging unwanted plants (weeds) with other plants is particularly interesting.
Much simpler and potentially more effective is to make sure there is diversity in your garden, whether you are growing annuals, perennials, or both. Sure, follow the companion planting charts if you wish, but think about getting rid of your garden rows or single crop beds, they are just micro-monocultures. A few marigolds planted at the end of the row will not deter the bugs in the middle of the row. Instead plant in groups or beds with a diversity of species—plant some herbs, grasses and flowers in your bed among your vegetables. When a bug flits from one plant to the next, let him encounter something that is not on his menu to interrupt his feast and confuse his senses instead of a long banquet table of his favorites. Also not all varieties of a plant work in the same way. Not just any marigolds will do, research indicates they should be French Marigolds.
Diversity in planting also allows different plants to utilize nutrients at different depths, in different proportions, and to mine and supply minerals to aid their neighbors. Trees do not grow in a forest in isolation, there are many other plants around them protecting and nourishing their roots—it is a symbiotic environment. Your garden will also benefit from such an environment. Consider what grew in your garden bed before the crop you are planting, and what will grow there next. Does the plant next to it have deep roots or shallow roots? Did the previous plants use a lot of nitrogen? Do the ones you are planting need potassium? Start each season with a soil test, and you’ll know the answer to many of the questions you need to consider.
Another element is cover crops. Contrary to popular belief, letting your garden lie fallow during non-productive seasons is not a benefit. The microbes in your soil that assist plants in absorbing nutrients need plants to live. The microbes feed off the sugars produced by plants and released through their roots. This is also a symbiotic relationship. Cover crops grown during off seasons can be selected to provide particular benefits, such as interrupting insect reproduction cycles, supplying a particular essential element such as phosphorus, potassium, or nitrogen, as well as organic matter to nourish your soil. They also discourage the rampant growth of weeds.
Rotating crops is also important for the same reason—interrupting pest reproductive cycles, providing a sustaining environment for microbes, accessing nutrients supplied by preceding crops and providing nutrients for the next crop.
All this sounds pretty complicated, but it doesn't need to be overwhelming. The gardening chart accessible on the VegHeadz Blog is an attempt to summarize these gardening elements for the North Florida gardener. Its links provide more information about cover crops, crop rotation, soil microbes, and gardening in our area. It is certainly not “all there is to know,” and will not fit every gardening need, but it does supply a lot of useful information, much of which is applicable specifically to our area.
With regard to companion planting, by all means use a variety of plants and observe what’s happening in your garden. Watch what works and what does not. Try to figure out why. Keep records if you are so inclined—it’s the only way to reach any dependable conclusions. But in the end, your plants will always benefit most from one particular companion--you.