Our favourite hardy annuals for spring transplanting.
I honestly can not get enough when it comes to cool flowers. These hardy annuals thrive in the cooler temps of early spring and bring some color to the garden much earlier than their more tender friends!
The stunning peach Icelandic Poppies at the top of this bucket of blooms are one reason everyone loves cool flowers!
In Part I, I talk about some of our favourite varieties of hardy annuals for direct seeding. In this section, I'll go over the flowers we choose to start indoors before planting out.
This requires a place to start seedlings—a greenhouse or an indoor growing area equipped with lights and heat mats. If you aren't prepared for that, head back to part I to review the plants we start from seed directly in the garden. Plants started without proper conditions (not enough light or heat) tend not to thrive. They will be leggy and weak as they expend energy searching for light.
I'll assume you have some experience starting seeds indoors for this post. If not, I'll share an article soon to help you get started :)
Why I start seeds indoors
- Get a jump on the season
- Some seeds require a long time to get established
- Some seeds are expensive, and I can't afford to waste any
- I don't want empty spots in my garden, so I start most seeds indoors to know I will always have a full bed. (Ok, I'm also a bit of a control freak ;)
- Putting larger plants in the garden helps to get ahead of weeds.
Look at this beautiful bed of 'Chantilly Light Salmon' snapdragons!
When to start your plants
- Calculate your seeding and transplanting dates based on your last spring frost date.
- Start planting out hardy transplants about 4-6 weeks before your last usual spring frost date. So, for example, if May 21 is your average last frost, count back four weeks. That puts you on April 23rd.
- After calculating your transplanting date, determine your indoor seeding date. Depending on the type of flower (more on that later), you can start seeds 4-8 weeks before planting out.
If you're unsure what your typical last spring frost date is, check out these average dates from Vesey's seeds.
Remember that this is a "rule of thumb," so you may need to adjust the timing based on your location. For example, if you typically still experience extreme freezing (light frost is okay) in late April, you should push your starting date back a week or two. I caution you not to push these dates to their limits. Plants can be set back if they outgrow their plugs or pots, and you won't be any further ahead than if you had waited a couple of weeks to get started! (Trust me, I’m talking from experience😅 )
With seeding dates calculated, you're ready to go! Ok, almost ready. Now we think about the particular needs of each plant. Some plants, like calendula, are quick to start and grow rapidly. If you start seeds eight weeks before planting out, you'll have monster transplants that have outgrown their pots and won't perform well in the garden.
Most Sweet William are biennials and need to be planted a year before (and have a cold period over winter) they will flower. This is a bucket of Sweet William 'Amazon Rose Magic,' a first-year-flowering cultivar.
Some of my top 'cool flowers' that I start as transplants
| Flower | Favorite Variety | # weeks before planting out to start indoors |
| Snapdragon | Chantilly Lt Salmon, Maryland Appleblossom, Madamme Butterfly Broze, Potomac Lt Orange | 6-8 |
| Icelandic Poppy | Colibri | 6-8 |
| Sweet William* (first year flowering varieties) | Amazon and Sweet Series | 6-8 |
| Foxglove* (first year flowering varieties) | Camelot and Dalmation | 6-8 |
| Rudbeckia | Indian Summer, Cherokee Sunset, Sahara |
6-8 |
| Feverfew | Magic Single | 6-8 |
| Monarda | Lambada | 6-8 |
| Scabiosa Atropurpurea (annual) | Blue Cockade, Black Knight | 6-8 |
| Strawflower | Apricot, Silver Rose | 6 |
| Calendula | Ivory Princess, Ornage Prince | 4 |
A field of blooming Calendula! We grow varieties such as Ivory Princess and Orange Prince. These types grow stocky, tall stems with very full blooms, which make them superior for cutting.
Even though they are cold-hardy, these plants will be more tender from their time indoors. Before planting, be sure to harden off your plants. This is the process of slowly introducing your plants to the outside world, helping ease the transition of exposure to the elements. Bring your plants to a protected spot outdoors for a few hours each day, returning them indoors before dark. Slowly increase the amount of sunlight and time each day for at least three days.
Once planted, these 'cool flowers' are tolerant of light frosts. We usually have a frost blanket ready just in case, though! Since we grow flowers commercially, we want to ensure our crop looks great and doesn't show any signs of damage; however, in a home garden, you don't need to worry!
