Another common question I get is, given a limited amount of space, what vegetables do I recommend people plant. A lot of my answer depends on the climate that you're gardening in and the length of the growing season.
In places like Houston, where I lived for awhile, the high humidity and mild temps allow for early and plentiful harvests of short-season vegetables like green beans, peas, summer squash, beans, and all kinds of greens. The challenge comes with long-season vegetables that require more days with fruit on the vine to ripen. The high humidity and abundance of insects in the heat of summer will wreak so much havoc that I would shy away from pumpkins and tomatoes that take longer to mature and focus on varieties that ripen over a short period of time.
In the Inland Northwest where I garden it's the late and early freezes that we have to work around. We have a relatively short growing season that starts on May 15 with the traditional last-freeze date and concludes on September 15 with the traditional first-freeze date. That being said, the hot weather required for tomatoes, peppers, and other hot-season vegetables usually doesn't kick in until mid June. Last year my cucumber starts sat in the ground without growing until the beginning of July because it was so cool.
Because of our limitations I usually look for varieties that require less time to mature. Take note that many of the heirloom varieties that are so tasty, like Brandywine tomatoes that take 85-100 days to mature, often have longer days to harvest. Many of the hybrids, like Early Girl tomatoes that mature in as little as 50 days, were developed to accommodate shorter growing season. The down side is that some of the hybrids don't taste as good. Early Girl tomatoes are, in my opinion, one such variety. It's always a balancing act but make sure you have enough time to get to harvest. Most seed packs include a number for "days to harvest" or "days to maturity and most plant starts have an information tab that also has this information.
Another key consideration is the growth habit of the particular plant variety you're growing. Most vegetable plants come in bush/determinate or vining/indeterminate growth habits. Bush varieties are compact and will only grow to a certain height and width and will stop setting fruit after awhile whereas indeterminate plants will continue to extend new growth and continue setting new fruit until freezing weather sets in. Going vertical with vining plants can be a great way to make use of limited space and bush varieties of pumpkins and summer squash can also be a good option for limited space.
One of my rules for selecting plants is to choose varieties are different than what is usually available at the grocery store. Instead of Russett potatoes plant Yukon Gold or French Fingerlings. Instead of iceberg-type lettuce plant a Mesculun mix or Red-Speckled Leaf varieties. Instead of planting Jack-O-Lantern pumpkins plant Wyatt's Wonder, one of my favorites. Instead of the old standard Black Beauty zucchini plant the Armenian or Golden varieties, that are much tastier. A big part of the fun of growing your own food is to try new foods.
In a limited space I would recommend the following:
1. Green beans - Bush or vining are easy to grow and provide abundant food. Stagger several plantings every two weeks for continual harvest. The Royal Purple variety is a fun one to grow. I usually prefer bush varieties.
2. Zucchini - Zucchini gets a bad wrap. We've all heard the one about locking your doors during the summer so people don't unload their unwanted zucchini on you, but we always plant a lot and have never had too much. The trick is to harvest them when they are small and tender, about the size of a banana. Don't let them grow to the size of a small tank.
3. Peas - My favorite is snap peas and they are best grown on a trellis or tepee.
4. Carrots - They don't need much room. Wait to harvest until the first freeze hits and they will be sweet and crunchy.
5. Kohl Rabi - These don't require as much room as cabbage and are tasty when they are baseball size. They get woody when they get much larger than that. I prefer the white variety.
6. Cucumbers - These can be grown on a trellis but, in my experience, are best grown on the ground where they have some room to roam. There are some bush varieties that work well too. Marketmores are good keepers but have thick skin. We grew a long skinny Chinese variety last summer that was awesome. I avoid pickling cucumbers because their window of opportunity to harvest before they turn into mini watermelons is too tight for my lazy harvesting habits.
7. Winter Squash (if you have room) - I love winter squash so I always make room for these. My favorites are Spaghetti Squash and Butternut. They also come in bush varieties.
8. Greens - Fill in the gaps of the garden with different greens. We love spinach, kale, and Mesculin Mix lettuce.
9. Tomatoes - If you've only got room for one or two tomato plants I recommend Sun Gold cherry tomatoes. They are the best tasting, off-the-vine tomatoes I've ever had. Their small size means that short seasons won't be a problem and they will keep producing and growing until frost sets in. They need some room to spread out because they are an indeterminate variety.
Those are my recommendations and I would set the priority based on what you like to eat. I guess I should also fess up that you need some substantial space to do all of the above which leads me to another conversation I'd love to have about why you should make more room to grow vegetables. Maybe that can be the next post in this series.
(The picture is from the Smithsonian collection of vintage seed packs and seed catalogs.)