Vegetables You Can and Can't Start Indoors

Some things are better left alone. That is plant them striaght in the ground as nature intended. A general rule of thumb is if it grows mostly above ground, you can start it indoors. If it grows mostly below ground, you need to directly sow the seeds in the garden.

Next is timing. The seed packs will give you a good idea about when to start them indoors. You just need to have a plan to transplant from your cells to larger cups, if the weather doesn't cooperate. You don't want your seedlings to become root-bound in the seed starting cells.

Things that like cool weather and can stand a little light frost are lettuces, kales, radishes, peas, broccoli, cabbages and cauliflower. These are the plants I can think of off the top of my head.

Things you can start indoors in cells.
Just about every herb but the favorites are chives, oregano, basil, parsley, lavender, rosemary, and thyme.
Just about every lettuce, kale, or cool weather green. And spinach and chard.
Others...
Broccoli, Cauliflower, and Cabbages
Peppers, Tomatoes, and Tomatillos
Cucumbers, Squash, and Zukes (I don't recommend cells but 8 oz cups)
Beans can... but they grow quickly if planted in the ground. (8 oz cups if you plant inside)
Melon, Lopes, and Gourds (8 oz cups if you plant inside)

Things I don't recommend starting indoors/Plant directly in the ground.
Carrots
Radishes
Turnips
Parsnips... you see the trend. Root crops need a lot of earth for their main root to extend.
Kohlrabi is an exception... I start them every year in cells. They transplant easily. The root does grow above ground.
Peas are best served in the earth.
Beets
Onion sets.
Garlic sets.
Bunching onion seeds.
Corn is the exception to the mostly above ground rule. Straight in the ground is best.

I hope this helps cover the main vegetables. If you have others please add them to the blog.