How important are companion plants in community gardens

Question

My partner and I will be getting involved with our first community garden this year (with a number of policies to ensure safe social distancing, of course). Having never really done gardening before, we've been doing a lot of research about recommended planting times in our area, companion planting, and trellising vining plants. To that end, we've come up with a layout that we think makes sense and will reach a local maxima (if not the best possible) for our garden. We've run into a bit of an issue where we're finding it hard to layout our garden without either

1. Removing a companion plant from its friendly neighbors, OR
2. Putting two adjacent plants that don't play well together

We aren't sure how significant companion plants actually are (or if some companions are more "helpful" than others), so we thought we would reach out. Our tentative garden layout(s) are below - we have two 10x10 plots that will likely be near each other but not adjacent. The layout was made in Excel; each cell represents a 1x1 sq ft region. We tried to space things out as much as we thought was necessary based on recommendations online (they are numerous, so I won't link them all here), but we also found lots of images of garden plots much more tightly grouped that seemed to be doing well, so maybe that would make it easier on us as well.

We are not especially concerned (nor are we able to be) about year-to-year rotation; the entire community garden is plowed over and the soil spread every year, and members do not get the same plot per year.

Any tips on how to best approach and layout the garden would be greatly appreciated! In the plots below, "top" == "North" (to avoid the trellised plants stealing too much sun).

The plants we definitely want to have are:

• Cucumber
• Zucchini
• Snap Peas
• Sweet Potatoes
• Rosemary
• Green Beans
• Potatoes
• Tomatoes
• Basil
• Celery
• Carrots

Other additions on there are ones that we're fans of, and that seem like they would do well in the garden. If there are better/more appropriate plants for companion planting that would also be helpful information.

Text-version of the plots:

First Plot:
________________________________________________________________________________________________________
|         |        |          |        |          |         |          |         |          |          |
|         |        |          |        |          |         |          |         |          |          |        
|         | Chard  | Chard    | Chard  | Chard    | Lettuce | Lettuce  | Lettuce | Lettuce  |          |        
|         |        |          |        |          |         |          |         |          |          |        
|         | Celery | Celery   | Celery | Celery   | Carrots | Carrots  | Carrots | Carrots  |          |        
|         |        |          |        |          |         |          |         |          |          |        
|         | Onion  | Onion    | Onion  | Onion    | Garlic  | Garlic   | Garlic  | Garlic   |          |        
|         |        |          |        |          |         |          |         |          |          |         
|         | Basil  | Tomatoes | Basil  | Tomatoes | Basil   | Tomatoes | Basil   | Tomatoes |          |
|         |        |          |        |          |         |          |         |          |          |
--------------------------------------------------------------------------------------------------------
Second Plot:
_______________________________________________________________________________________________________________________
|         |          |          |          |          |            |             |            |             |         |
|         |          |          |          |          |            |             |            |             |         |
|         | Cucumber | Cucumber | Cucumber | Cucumber | Zucchini   | Zucchini    | Zucchini   | Zucchini    |         |
|         |          |          |          |          |            |             |            |             |         |
|         | Peas     | Peas     | Peas     | Peas     | S Potatoes | S Potatoes  | S Potatoes | S Potatoes  |         |
|         |          |          |          |          |            |             |            |             |         |
|         | Rosemary | Beans    | Rosemary | Beans    | Rosemary   | Beans       | Rosemary   | Beans       |         |
|         |          |          |          |          |            |             |            |             |         |
|         | Potatoes | Potatoes | Potatoes | Potatoes | Potatoes   | Potatoes    | Potatoes   | Potatoes    |         |
|         |          |          |          |          |            |             |            |             |         |
-----------------------------------------------------------------------------------------------------------------------

Answer 1

You should note that related plants can share diseases and pests. The two botanical families that this applies to most are the Solanaceae (tomatoes, potatoes, peppers, and egg plant) and the Cucurbitaceae (melons, squash, and cucumbers). This means that you should never use the same plot for the same members of these families in successive years. In other words, you'll need to rotate your crops, following tomatoes, for example, with cucumbers and then with onions or legumes or root crops or leafy crops.

Personally, I always plant tomatoes, peppers, etc in one plot of my garden and melons and cucumbers together in a different plot. I have four active plots in all, averaging maybe 6ft x 10-12ft (2m x 3m+) in size, with paths in between. My rotation is:

• Legumes (usually beans, both shelling and cooking)
• Melons (for the higher nitrogen levels left by the legumes), with a mobile trellis for cucumbers.
• Tomatoes, peppers and the occasional eggplant. Because of crop timimg I often plant a row of peas on a mobile trellis at the back of the tomato bed. I grow the tomatoes in cylinders made up of heavy gauge wire in a 5in (10cm) grid.
• Root and other vegetables (carrots, beets, onions), planted in staggered rows.

I also plant garlic rather randomly throughout the beds.

I see by your profile that you live near/in Madison, Wisconsin. I live about 15 miles south of Madison so we share the same climate. Some comments on your plans:

• In general, I don't think you leave nearly enough room for some of your plants. My tomatoes easily take up 3 sq ft each in their cylindrical trellis. I think you might be better served by breaking you plot into larger grids (say, 2 ft x 2 ft) and then planting accordingly (one tomato per grid, one zucchini per 2 grids, etc.)
• Trellising your cucumbers and tomatoes is a must, due to your space requirements.
• If you haven't already started the celery indoors, it's too late, unless you can find a supplier in the area (celery is not a popular crop here, so not sure if you can find any).
• The onion sets you can find in many grocery stores will work fine in your garden, but don't plant the poor-looking ones (they won't produce much of anything). You'll probably wind up tossing about a third of the sets that you buy.
• Rosemary is not winter-hardy here and does best in pots in an east-facing window. Use high-quality potting soil (not the bags you see in a box store - go to a garden center (there's one near where you work, on Verona Rd). I would buy a single plant. If your intent in growing rosemary is for companion planting only, then don't waste your money (see the link I sent in my comment).
• You may have to hunt to find decent basil plants (if you haven't started your own from seed or cuttings). There are multiple types of basils, so be sure that you get one that you like.
• Think about succession planting. For example, after your lettuce has bolted in late June, what will you put in those grids? If you put nothing, you'll get weeds. You could wait until late July and then plant a late crop of beans, which you could harvest in late September, if not before.
• For ease of crop rotation, I would plant the tomatoes and potatoes in the same half of the same plot, and the zucchini and cucumbers in the same half of the other plot (like you have them).
• Sweet potatoes are not members of the Solanaceae. so you can plant them wherever you like. They are not easy crops to grow in Wisconsin. They also take up quite a bit of room (like 2-3ft each). Same with Zucchini.
• Zucchini are generally huge and very prolific. You could probably get by with a single zucchini plant, grown on a trellis. You might be able to find a bush zucchini locally; if not, grow them from seed next year.

I can strongly recommend the following book: The Wisconsin Garden Guide, by Jerry Minnich. It has all the information you could want on different varieties of vegetables and fruits - and on perennial flowers, should you ever want to expand in that direction. It also includes information on pests and diseases, as well as seed starting instructions which you might find helpful in the future (the best tomatoes are NOT those available from box stores).

Good luck!