If you want to maximize your garden space, and perhaps even improve the quality and flavour of your tomatoes, companion planting is a great way to accomplish all of these goals!
Companion planting simply means putting plants that grow well together in the same space. Some plants will inhibit each others’ growth or encourage disease or pests, so it is important to research which plants are good companions before filling up your space.
I like to think of companion planting as generally one rule and one exception, to guess which plants will grow well with tomatoes before I look it up to confirm. The rule is – Is it something that tastes good when paired with tomatoes? E.g. onions, garlic, herbs, cucumbers. Most of these plants grow well with tomatoes, however there are exceptions. The exception is – Is it in the same family (nightshade) as tomatoes? E.g. peppers, eggplant, potatoes? If so, they should not be planted with tomatoes because they share common diseases and pests. And the stuff that isn’t naturally a tomato-buddy in the kitchen, like corn, is usually not going to be compatible but it’s always a good idea to look up to be sure!
Another thing to consider is how much sun your tomato plants will allow their companions to get. Some herbs like oregano, thyme, and basil can tolerate shade, so as your tomatoes get bigger over the summer and gradually block out most of the sun from getting to the herbs, this is not that detrimental. Last summer I discovered that parsley does not like its sun access being blocked, as it bolted as soon as it became shaded over. I also tried to do a couple plants of leaf lettuce mixed in with the tomatoes, but they got so little sun that they didn’t survive.
Apparently when tomatoes and basil are grown together, this actually improves the flavour of both – I haven’t done a side-by-side taste test of tomatoes grown with and without basil to verify, but since I heard about it I have always planted basil in with my tomatoes.
I often seed a few nasturtiums in with tomatoes. Supposedly they act as a sacrificial plant; pests that might normally bother tomatoes will be attracted to them instead. You can also eat the nasturtium flowers – I think they taste a bit like arugula – which is a very fun way to fancy up any dish that could use a peppery kick!
When I plant my companion herbs in the tomato bed, I plant them midway between the tomatoes on the outer edge, as close to the edge of the bed as I can. This gives them a bit more access to sun than if they were in the middle. (Sorry that these pictures aren’t great.)
I have no idea if companion planting actually gives me any flavour or pest reduction benefits, but it helps me make the most of my small space, I generally don’t have pests, and my tomatoes always taste pretty good!