If you love to have fresh vegetables (like I do), but are stymied by the short growing season we have here in the upper Midwest, it’s time to look at how you can extend your growing season to get more fresh foods from your garden.
Let’s start with some definitions:
When the weatherman predicts a light frost, he’s talking about temperatures in the mid- to low-30’s. Light frost is when dew freezes in the early morning hours, forming a light film on the plants. Depending on wind and other conditions, this can happen between 32°- 34°. Even just 30 minutes at 32° can produce a light frost. Plants that are cold sensitive will likely not survive a light frost.
When the forecast is for freezing temperatures, the weatherman means that the temperature will be at 32° or below for several hours. This is the test of a plant’s cold hardiness. Plants that are cold-tolerant may survive several hours at 32° but will not do well when temps get just one or two degrees below that.
A hard freeze means Mother Nature is serious about winter.
During a hard freeze temps will get as low as 28°for several hours during the night. Most people call this a killing frost as it will kill just about everything in the garden that’s not protected.
The Plant Side
Now let’s look at the plant side of the equation. Some plants are super fussy about cold temperatures. The slightest hint of frost and they will wilt and turn black. These cold sensitive plants include:
- Sweet Corn
- Tomatoes
- Beans
- Cucumbers
- Eggplants
- Peppers
- Okra
- Pumpkins
- Summer Squash
- Winter Squash
- Sweet Potato
- All Melons
- Most herbs (Parsley and Rosemary are more cold tolerant)
Cold Tolerant Plants
Cold tolerant plants are plants that are OK with a little bit of frost. In fact peas will germinate better in cooler temperatures and will stop producing when it gets hot. But don’t push these plants too far. Sustained temps below 32° will be the death of them.
The cold tolerant plants include:
- Bok Choy
- Cauliflower
- Celery
- Peas
- Quinoa
- Radicchio
- Parsley
Focus on cold-hardy plants
Cold-hardy are the plants that are the foundation of extending your garden season. These plants will get a head start early in the spring and continue to produce well into the fall. A light frost or freeze hardly seems to faze them. In fact, the flavor of the brassica plants (Broccoli, Kale and Collards and Brussel Sprouts) actually improves after one or two nights of freezing temperature.
Here is the impressive list of cold hardy plants:
- Arugula
- Broccoli
- Broccoli Raab
- Brussels Sprouts
- Beets
- Cabbage
- Carrots
- Collards
- Endive
- Kale
- Kohlrabi
- Leeks
- Lettuce
- Mustards
- Onions
- Parsnips
- Radishes
- Rutabaga
- Spinach
- Swiss Chard
- Turnip
The great thing about this: many of the plants on this list store well in the root cellar. That means that not only can you delay the harvest for a few weeks (and thus have less of a rush in the fall) but most of these are long-storers. So you’ll be eating fresh vegetables out of the root cellar for most or all of winter.
If you plan now to protect these plants in early spring and late fall, you could have fresh vegetables on your table for seven months or more each year.
Brussel Sprouts?!? Yuck!
Most people don’t like Brussel sprouts because they tend to have a bitter taste. That’s because they’re all grown in California or Mexico where they can grow year round (which is good) but never get touched by frost (which is why they’re yuck.) But if you harvest the Brussel sprouts after a good frost, they’ll be much sweeter and you just may find yourself a big fan of Brussel sprouts.
And here we have a chart illustrating all of this. You can also download a poster-size for free in the PHC Store.
