Hardy, as in leave in the ground overwinter, hardy? Not much as I recall. Some varieties of garlic are usually harvested in the spring (and thus are truly hardy) if memory serves. I honestly don't know about carrots -- my folks gave up on them long before I moved out & down to the the SE part of the state. (Ours always came out as these weird multi-legged looking things. You would have thought we had mutant carrots from an alien world.)

Though I have never tried it, I have known folks who would plant leaf lettuces up against their house and then as temps got dangerously chilly would put a cold frame over that area. Doing so enabled them to harvest lettuce through much of the winter.

Veggies like lettuce and the rest of the cabbage family can be sown/planted in the spring but will not be ready to harvest. Peas are also generally a cool weather crop -- typically sown/planted in the spring and harvested early summer. By mid summer the plants will be toast. They simply do not do well in heat. However, a second crop can be sown near the end of summer for a second harvest but considering how unpredictable our weather is, you may or may not actually succeed in getting that second harvest before the hard frosts kill them.

Some of the herbs like oregano can overwinter successfully in the ground. The one at my folks' place blooms until snowfall.

Two good ways to learn what works for you / your area:

1. try a few things - plant every couple of weeks, cause each year the weather is a little different. And you'll potentially extend your harvest as well.
2. find a farmers' market somewhere in your area - most won't have much until maybe early June? (check your newspaper or Chamber of Commerce for when they open...Visit every few weeks to see what they have to offer when... and then ask them when/how they started their crop... if you buy something and visit when they're not too busy, I've found they will spend a few minutes answering a few questions.

Although a reasonable number of 'cold season' crops can be planted early, many will not mature for a couple of months or more. And many seeds may be slow to germinate if the soil is really cold...

The earliest 'harvested' things will be lettuce, spinach, radish... All the items will be 'annuals' - some you can keep in the ground into the fall until you're ready to harvest (carrots, depending on when you start them).

If, by hardy, you mean can you grow them in your climate - yes. If you mean will they last multiple seasons - No.

A couple of perennials that grow and produce over multiple years, and are harvested fairly early would be asparagus and rhubarb.

Beth
Z5 northern Michigan (near Traverse City)

I'm sorry I didn't mention this before, but the whole 'not being able to grow stuff in the ground due to frozen soil' doesn't apply to me.

This is because I don't grow stuff in the ground, I use container gardening. Please do not tell me to post this in container gardening.

I'm merely bringing up container gardening, because I don't grow stuff in the ground, so the issues with growing stuff in the ground, don't apply to me. I merely provided that info for the sake of clarification.

Actually the two questions asked about 'whether I can grow the stuff in my climate' and 'will they last multiple seasons' isn't what I was asking about.

What I'd like specifics on regarding hardiness is which cold weather crops are hardier than others. I bring this up because I know all cold weather crops grow well in cold weather, but I know some cold weather veggies in comparison to others, are hardier. That is they can withstand colder temperatures than others.

I basically wanted to know of the veggies in the list above, which are considered very hardy and what is the lowest temperature range they can endure and survive. By 'survive' I mean come out of it healthy, not just struggling to survive and/or dying.

I also wanted to know of the veggies listed above, which can survive moderate to heavy frosts (again 'survive' basically is the same definition I used above) and which can't.

carrots, kohlrabi, beets, turnips, cabbage, broccoli,broccoli raab (it's similar to broccoli but has shoots coming out of it)
mustard greens, kale, collards, daikon ( large, white Asian radish), red radish, Swiss chard