Cool Season Annuals…What Are They, And When Do You Plant Them?

The Birmingham area can see great fluctuations in temperatures in any given year, from sizzling summer highs in the upper 90’s to lows well below freezing in the winter complete with rain, sleet and even snow (Look HERE for a post on the blizzard of ‘93.).

Ornamental kale, trailing pansies, Euphorbia ‘Ascot Rainbow’

Winter planting of cool season kale and pansies

For gardeners this can present a quandary when trying to decide among the dizzying array of plants at the local garden center. While the last average frost date here is mid-April, the soil can still be too cold for the real heat loving plants like zinnias, impatiens, lantana, and caladiums, to name just a few, that will sail through our blistering summers but languish in cold soil.

Enter the cool season annuals. These are the plants that prefer cooler temperatures and thrive in the early fall, winter, and early spring. If you know which ones they are and when to plant them, you’ll be ahead of the gardening game.

Foxglove after days of freezing temps

A few days ago, after we experienced temperatures in the teens at night with snow and cold weather for a number of days, I checked on some of my winter grown cool season plants to see how they’d fared.

The pansies, poppies, snapdragons, and foxgloves are very hardy plants that I’d added to the garden in October and November, though if you find larger transplants they can be planted in late winter as well. They looked fine, though some that were more exposed had damage. As temperatures warm they should rebound nicely.

But, since they’re also considered cool season annuals, they’ll fade as our spring heat arrives for good in May. Then it will be time to replace them with the real heat lovers I mentioned earlier.  Remember, our last average frost is right around mid-April. We can count on things warming up quickly after this date. This is also about when everything in sight is turning yellow from the pollen falling everywhere – including covering cool season plantings and our cars!Poppy - Buds Frozen

Cool season annuals have a tough life. They might like it cool, but freezing is a bit much even for them. The picture of the poppy here shows what happened to the majority of them that were just beginning to put up fat buds when temperatures dipped into the teens for a few nights in a row.

The buds were completely frozen, but the plant itself came through fine since since mulch helped keep the plant and rootball warm. They too will be in full bloom in another month or so and are examples of what can be planted from 4″ pots in the fall.

The second picture shows (circled) seedlings of larkspur and poppies grown from seed sown  directly into the garden in December. I sow extras any time from November to January when the soil is cold enough for their liking.

Poppy and Larkspur seedlings and a SnapdragonAt any rate, you can see these tiny plants in this sunny, south facing bed weren’t fazed by the cold temperatures at all. I’m looking forward to their blooms in the late spring!

Some other cool season annuals that are more frost tender will begin to arrive in the garden shop soon. They  include sweet alyssum, geraniums, petunias, nasturtiums, bacopa, and more. Because they come out of cushy greenhouse environments you’ll want to protect them  from any late freezes.

We’ll check back on these plantings in future posts.

 

By Kris Blevons