You can grow a surprising amount in containers. Most people who are container gardeners also have limited space, so focus on the high value plants - herbs, leafy greens for salads and stir-fries, green onions, patio tomatoes in summer and kale and chard in winter. Dwarf snap and snow peas grow happily in containers. I have heard that they are great in salads but none of mine ever made it inside. Containers can also be used to lift the garden up to where the gardener can reach it for gardeners who are not up for bending and digging.
Some plants belong in containers even if you have room for raised beds. Peppermint, apple mint, and catnip are notoriously aggressive spreaders. Comfrey is useful in the garden and medicinally but becomes a nightmare if allowed to spread. Some annuals, such as bronze fennel and figwort (both wonderful pollinator plants), are joyful self-seeders and best placed where they will not launch myriad seeds into your raised beds.
Some good container gardening books are The Bountiful Container by the daughter from the Nichols Garden Nursery family and Edible Container Gardening by Michael Guerra. This last is less comprehensive, but it contains the story of the author's garden, how it went for them and what they got. It also contains some bloopers. Those of you who have taken the fruit tree classes at Cloud Mountain or already know about growing fruit trees will scratch your heads at Guerra's description of planting annual vegetables among the roots of a dwarf plum. There are many other container gardening books out there to get you started.
Nearly any sturdy container is suitable for gardening. Back on the block in my old neighborhood in Chicago, old toilets recycled as garden art spilled nasturtiums and zucchini. I always thought it was some kind of existential joke.
They planted tomatoes and potatoes in old tires, too, back on the block. The tires warmed and protected the plants, which are after all from Central and South America. Don't do it yourself, because tires are way too toxic for a food garden.
For food gardening, you'll want some good sized pots, at least two gallons, preferably five. The big ones get pricey, so this is an opportunity to practice your scrounging skills. I once met a container gardener confined to a wheelchair. He had a whole food garden planted in everything from gifted clay pots to a repurposed plastic milk carton.
The books go into suitable containers, watering arrangements and soil in detail, but the short version is that pots need drainage, steady moisture availability and good potting soil. In addition to holes in the bottom, large containers need a couple of inches of gravel or broken clay pots in the bottom to provide drainage. For small containers, you might want to buy premixed potting soil. That gets pricey for large pots. Here's my potting soil mix: One part any available garden soil, one part compost, and one third part vermiculite or perlite, a generous scoop of organic plant food and inoculate with compost tea. All containers from clay to repurposed laundry baskets eventually succumb to freeze/thaw cycles, weed whacker damage, sunshine breaking down the plastic or ten year olds on a bicycle.
The soil in containers get exhausted, particularly if you are growing nutrient hungry annual vegetables. At the end of the season, the best thing to do with small containers is dump them out on your raised beds. This both expensive and challenging for bigger containers, so I grow cover crops in mine. Yes indeedy, your farmer friends will smirk when they see summer buckwheat, fall fava beans, winter vetch, and spring oats in your collection of artistic Mexican hand thrown pots. It works, though. Grow a cover crop, turn it under in the green leaf stage, let it break down for a couple of weeks, and you are set to keep that potting soil going for years.
This my basil growing technique. Basil is another plant well suited for containers, just because it needs to be fussed over and slugs love it. First, start annual clover in the container in early spring. Now, for example. A month before you are ready to plant out your basil starts, cut the clover to the ground with your nail scissors (container gardeners don't need large tools) and grasp the whole mass and lift it out of the pot. Drop the cuttings in the bottom of the pot and turn over the whole root mass. Cover the pot to exclude light while the roots decompose. Meanwhile start your basil. Plant basil seedlings into the root mass with a handful of Sluggo (non-toxic iron phosphate and corn meal) to keep the slugs down.