The advantage to starting seeds indoors in early spring is obvious. You get a jumpstart on the the season. But it really depends on which vegetables you're talking about. Tomatoes, eggplants, and peppers are very frost tender and take a long time to grow and mature so they really need to be started indoors. Most other things you'll only get marginal benefits from if you start them early. While still others do best direct sown.

Rodney

I have started seeds for transplanting because of the wet conditions. I started cukes and squash because they just rotted in the wet ground. I don't start inside in the summer, I plant in seed tray that are outside under an overhang to protect from the worst weather. If the conditions of good I would direct seeded. But this year in my area you had do what I had to do to get plants in the ground.

I routinely start seeds in 4-inch pots outdoors once the weather gets nice. Why in the world would I want to do that inside?

Now, if this is about direct sowing versus seedlings in pots, that's a different question, and has to do with the soil conditions. Also, seedlings in pots are immune from cutworms and soil-borne nasties, which are of greater danger for seedlings than for larger plants. Also easier to keep the pot medium moist than the ground. Transplant shock? Not unless the plant is root bound, and is being moved to a location where the conditions are very different.

A lot more work to transplant from pots? I don't see it. I think it's a lot more work to protect fragile seedlings just emerging from the soil.

I start all of my annual/perennial flowers inside in the winter because it gives me as much as an 8 week jump start to a colorful spring. I germinate them in seed flats, then transplant them into plastic cell packs for their two month stay under lights.

Tomatoes are the only veggie that I grow from seed inside, again for the two month head start. All others are direct sown at the appropriate time for the variety.

Year in and year out, I usually grow about 600 plants and I have to say that I scratch my head when I hear anyone talk about 'transplant shock'. If there are issues after transplanting then you are doing something wrong. It's not normal for a healthy plant of any kind to suffer after the transplanting process.

I can tell you why I do not direct sow many things at this time of year and instead start with pots (although they are outside). Number one, there are some things I need to get started now, even though their space is not clear. For my climate, the time to start fall crops like Brussel sprouts, cauliflower, etc, is right now. However, the places I may want to plan those are currently occupied. I use a lot less water when I germinate seeds in seedling trays than if I were to use the hose in the garden proper (rain is great but cannot be counted on me for me). Also, when I have all of my seedlings together on the porch, it is easier for me to monitor them whereas if a day is quite busy, when I am doing my round of the garden, I might overlook the new seedlings. It is also easier for me to protect the seedlings from birds if they are on my porch or somewhere consolidated than spreading out row cover fabric all over the place.

Rhizo said it well. "Transplant shock" means you did something wrong when you transplanted. No plant needs to see transplant shock.

But again, the question here isn't why you should start things indoors in the winter (we all do), but rather how one should start them outside when it's summer. Tishtoshnm's point about winter veggies is a good one. If you're trying to start winter veggies outdoors, it saves bed space if you do it in pots. If, on the other hand, you're trying to start summer veggies outdoors, then in principle it shouldn't matter, though row crops like corn and beans are obviously not things you want to transplant, though.

I have started fall broccoli by direct sowing and by sowing in pots on the picnic table. I have had FAR better results starting them in pots. The flea beetles used to decimate the direct sowings from day 1 that they came up...and they were wasteful in getting the rightly spaced stands....tomatoes for a fall crop...about the same story.

Now fall butterhead lettuce and spinach here have to be sown INDOORS where it is cooler to get a good stand.