Answer: Planting side by side can be an issue if the plants have very different watering needs or if a tall one is going to shade a sun-loving shorter one. Other than that, your real concern is in the succession. You want to rotate your plantings from year to year so certain plants do not follow each other being planted in the same spot. This will help reduce problems with pests and diseases. Probably the most critical would be members of the Solanacea family (eg tomatoes, potatoes, peppers, eggplant) and Cucurbits (cucmber, melon, squash, zucchini). This means for example if you grow tomatoes in a certain spot this year you should not plant tomatoes or other Solanacea members there next year. Here is a little more information about this that may be helpful.
Have fun with your new garden!
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