Aside from starting indoors like you mentioned, you can leave a bed open after spring vegetables are harvested, or you can start seeds beneath tall summer plants.
I think in places with hot summers starting indoors is the best option.

Yes the seasons do overlap but my summer vegetables get pretty tired during the summer heat. I don't try to carry over tomatoes unless they are cherries. I just replant in July. I do keep the peppers and eggplants but the squash are replanted. Cucumbers can be hit by cucumber beetles and I replant them too. It also helps not to plant the whole garden so I keep a few areas open.

You can also plant lettuce and radishes and beans under the larger plants. This works really well in wide rows but might not do so well in square foot gardening. That's one of the reasons I still do row cropping.

Now if you've planted potatoes and corn, they should have been harvested and open up room. Same with the onions. I think the real problem is that most people in Texas only plant a few different types of vegetables that are perennial in their native tropical setting. Since we rarely have a real spring and fall, we don't "feel" the proper time to plant veggies that like cooler weather.

That's my 2 cents worth and I had the same problem but after missing fall veggies for a few years, I forced myself to cull and replant and have been satisfied ever since. Good luck

Ohh, lordy. I have spreadsheets and diagrams where I chart everything out (no joke), but I'm an analyst by day so I can never resist.

For me, it takes a ton of planning because my space is limited, complicated because I'm growing from seed, so I can't go "Oh look, an open space. I'm going to go buy a plant."

But some things get pulled early, other things get planted late. Really, only my tomatoes are in dedicated spots where no spring or fall crops are planted, because where I live, they run from May through November and pretty much suck up both sides of my growing season.

I have places where I plant spring and early summer veggies (peas, broccoli, cabbage and an early crop of zucchini). They get pulled in time to replace them with my fall plantings (also peas, broccoli, cabbage and greens). But suffice to say, when I combine succession plantings with crop rotations, I've basically had to draw pictures of my garden with start/end dates to figure it all out.

Oh, and I added three wine/whiskey barrels so I had more garden space! LOL

Hope that helps!

Here is a link that might be useful: my blog

Farmerdilla has been a great source of help for me on this. Here's what I did last year, and it was greatly successful.

In July, start seeds for collards, broccoli, cauliflower, and cabbage in shade outside with dappled a.m. sun only. Keep them watered and fertilized, etc.

In the meantime you must allow some summer crops to peter out. For me, that was cowpeas, some pooped tomatoes, and squash (due to vine borers). You must plan for this if you do succession planting. The last week of August or the first week of September, direct sow turnips, kale, rutabagas, mustard and any other Asian greens. In mid September, plant out your transplants that were begun in July. In late September, set out onions, garlic, and direct seed carrots and lettuce.

Just FYI, I sowed a fresh trellis of pole beans last year in August and they came up and bore gourmet quality beans all the way to frost. That was a "I wonder if..." that worked famously.

Also, it's wise to not plant brassicas in the same place that the tomato family has just been. So pay attention to your rotations.

You may not want to plant all this, of course. Hope this helps!

Here's another fall garden question from a total newbie (working in my first veggie garden ever this spring). What's the best way to start tomatoes and peppers for the fall garden? Can I just direct sow seed? I tried starting transplants from seed for my spring garden and failed, ending up buying transplants. It seems like direct sowing might work in the fall though since they would be starting when it's nice and warm... Any opinions?

In Michigan, lettuce peters out in June-July. It can be replaced by radicchio in June, and broccoli, collard, lacinato kale in July. Farmerdilla's citation covers it, but it is important that brassica be grown in cooler temperatures, indoors or in shade. Radicchio can be direct seeded.

August is when we pick garlic and onions. Turnips and kale go well there, but this year I will try chinese cabbage too.
Turnip can be direct seeded.

In september, as the tomatoes slow down, you can plant arugula, broccoli rabe, and spinach under them, all direct seeded.

In your warm zone, I recommend also cattle fava (Banner) grown for greens, direct seeded in september. Here they don't make it through the winter and I just grow them in spring. Great for you and for the soil.

Thanks everyone for your feedback! I'll try to plan accordingly this year and see how it goes lol.

I'm in my transition period now, pulling out the snap peas, beets, garlic, spent broccoli & cabbage, bolting cilantro, ... and pampering the beds with new compost and organic amendments. I have flats of tomatoes, peppers, basil, squash and cukes I'm germinating or are ready for transplant and I'll direct sow a few other veggies. I'll plant flats of the cool weather crops in mid-Oct and transplant in Nov.

12 month gardening is a bit exhaustive and definitely takes some planning. Something to be said for fruit trees, grapes, artichokes and other keepers who I don't have to continually rotate (although they do have other issues)