When it comes to cool or hardy annuals, the right planting time is very crucial to save the investment of seeds and work, especially if we talk about hardy annuals, such as larkspur, Iceland poppy, or some peas varieties that also survive in cold climates instead of going into dormancy like common cool season annuals, such as Primrose, Snapdragon, and Nemesia.
However, some hardy annuals may also be dormant when the temperatures exceed or fall below their preferences. Many gardeners and resources say to Plant cool season annuals in early spring (March) or late fall (November).
They are almost half true, but when it comes to planting hardy annuals, especially true hardy annuals that are annuals natively, only the fall season is the perfect time to sow their seeds.
So, today, in this content, we will discuss the same topic (when to plant hardy annuals seeds) so that you can be satisfied to plant their seeds at the right time, especially in cold climates.
Before moving on, you must know how environmental factors affect plant growth.
What are Cool Season Annuals?
Cool season annuals are plants that complete their lifecycle in one season, some go into dormancy when their ideal temperature is not given or their minimum tolerance is exceeded due to seasonal changes, while some still survive even in harsh winters of -45C, called hardy annuals.
For example, some perennial varieties of larkspur, such as mountain or candle or larkspur and some peas varieties, such as sweet and snow peas.
Do you know? Larkspur is the natively perennial flower plant.
Now, here comes another confusion: why is the larkspur plant classified as hardy annual when it is perennial? So, the simple answer is that every perennial has adaptive features that help them adjust according to the provided climate, but they are still perennial natively. And their same adjustment can be in the form of annuals or even biennials.
So, the annuals whose right time we will explain in this article are actually true annuals, meaning plants that are natively and genetically annuals.
Because fall time to plant matters only for these true annuals, such as Love in Mist (a flowering hardy true annual) and peas (vegetable true hardy annual).
When to Plant Hardy Annuals Seeds?
Quick Understanding: Fall Vs. Spring Regarding Root Growth & Blooming Density
Root Growth
Blooming Density
Why fall (November) is the right planting time for true annuals?
By the way, different seasonal temperatures exist based on different regional climates; for example, colder areas like USDA zones 1 to 6 experience long and harsh winters, while tropical areas from zones 9 to 13 have mild winters. So, the real planting time for hardy annuals depends on your local climate.
However, let me show you when to plant hardy annuals based on general seasonal temperatures.
Fall is the more perfect season to plant hardy annuals compare than spring, and an author and farmer Lisa also recommend fall season to plant hardy annuals.
I would never say that early spring is not appropriate for hardy and cool-season annuals but it may cause poor growth or fast growth, leading to the inferior harvest as i get in peas growth.
Above all, the summer in the middle affects its growth, depending on the temperature in summer, which varies based on the region.
Discover the Summer Gardening Guide 101
Why early spring (March) is not a suitable time to plant true hardy annuals?
To explain this, I will tell an incident that happened to me. Actually, I had grown peas in the early spring of last year, but my country (Pakistan) is in the sub-tropical climate, where the maximum temperature goes up to 50 degrees Celsius. Since peas are cool-season annuals, they cannot tolerate the heat.
As peas were planted in the early spring, they grow 7 inches tall until May when the area experiences temperatures above 30C.
But when summer has come, the temperature was very high, due to which my peas were damaged, as peas can tolerate 29C maximumly.
And if we talk about flowering hardy annuals apart from vegetables, the same thing happens with them. If you grow hardy or cool-season annuals whether its vegetables or flowers in early spring, they cannot tolerate the intense heat, depending on the regional season’ temperature.
Cool or hardy annuals are already accustomed to growing in cooler climates, and each hardy annual has different maximum and minimum temperature tolerances.
Gardening Depends on the Regional Climate
But still, whether or not to grow hardy annuals in early spring depends entirely on the regional climate and spring-to-summer temperature.
In areas with mild spring and summer, such as zones 1 to 4, early spring (March) can be a good time to plant cool-season annuals, while in areas where temperature increases from spring onward (such as tropical and subtropical regions) the fall (November) or direct winter (December) will be the best time.
One point to understand!
One thing to understand here: the fall season is not the perfect time for only hardy annuals, but it is also the ideal period for cool-season annuals that can handle little frost during winter. You can adjust “When to plant hardy annuals” according to minimum temperature during winter.
Why Fall (November) Season is the Perfect Time to Plant Cool or Hardy Annuals
So, let’s see why the fall season is the best to plant cool or hardy annuals.
When you plant cool or hardy annuals in the fall season (November), the planted annuals establish their roots before the first frost. So, always try to plant seeds of hardy annuals before 4 to 8 weeks of first frost.
Then, as winter comes, dormant annuals such as Primrose, Snapdragon, and Nemesia stop to grow more while the ones that tolerate cold, called hardy annuals, continue to survive a little bit, such as some cool-season flowers (larkspur and Iceland poppy) and vegetables (carrot and lettuce).
But it truly depends on how much you protect them during intense frost (that exceeds plant preference). Here you can discover how to prepare and protect your garden for winter.
In both cases, plants stay alive because they are already cool-season or hardy annuals.
What Happens After Spring?
As spring begins, all those cool-season annuals already planted in the fall begin to get a huge growth boost. Dormant annuals, like primroses and Nemesia, now start growing again with renewed vigor as temperatures warm.
On the other hand, those that continued to grow somewhat during the winter, like larkspurs or radishes, have already established strong roots, which allows them to grow rapidly as the days get longer and warmer.
The result is an unusually bountiful harvest—flowers bloom profusely, vegetables ripen quickly, and the garden begins to present a beautiful spring scene.
All of this is thanks to planting at the right time, which gives the plants the best growth cycle and yields them abundantly!
Final Thoughts: When to Plant Hardy Annuals?
Finally, it has been proved that fall (November) is the best season to plant cool-season or hardy annuals but depends on the regional climate. So, always check temperature whether its fall or spring and then start planting cool-season annuals. Just make sure conditions should be cool from germination to harvest.
Still, several factors, such as region climate, annual variety and its season preference exactly decide the right answer of “when to plant hardy annuals?”. So, check all factors and plant annuals seeds according to your situations.
Enjoy The Cool Season Annuals!
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