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  • Writer's pictureHeather Thomas

Tips for All-Season Color: Plant Multi-Season Cultivars

How to mix early, mid, and late-blooming cultivars to create flowery borders

People often ask me how I keep the show going so continuously at Cape Cottage Garden. Let's continue our blog series, the "Four C's of Continuous Color." Today, we'll talk about another "C" in my approach - cultivar selection.
The range of bloom times within a particular genus is astonishing. By planting a range of early, mid, and late cultivars that bloom in succession, I've been able to create an ongoing progression of flowers that bloom all season long. I first grasped the value of this approach when I sought to extend my tulip season. By being intentional about what I planted, I discovered I could extend my tulip season from a short 10-day period to nearly five weeks. See below for an example of the different cultivars that help my tulip season last. A "double early" cultivar such as 'Foxtrot' might open for me in mid-April whereas a "double late" cultivar such as 'Yellow Pomponette' often carries me through the second week of May.

Besides tulips, many other perennials, from peonies to alliums to astilbes come in early, mid, and late varieties.
To discover your options, it's helpful to do a little research online when making your plant selections. For example, when I was planning my allium garden, I consulted this handy bloom time chart from Longfield Gardens.

Source: Longfield Gardens

Using this chart, I was able to plan my allium season so that it lasts for months. The season here starts in mid-May with 'Purple Sensation' and 'Mt. Everest' and extends nearly to July with Allium sphaerocephalon, commonly known as drumstick alliums.
Salvias and nepeta are other examples of flowers that I get to enjoy for longer in my garden because I chose a range of cultivars as shown below.

If you love a particular type of flower but wish it bloomed longer, perhaps you can find an early or late blooming option in the genus that can extend the form and color in your garden.

For example, if you love peonies but wish they bloomed much longer as I do, you might be interested in the "Bloom Time" project which has been published by the American Peony Society. This project records the bloom time of hundreds of peony cultivars using one specific cultivar - the mid-blooming peony, 'Red Charm' - as a baseline. Each peony cultivar is recorded with an "offset" number, meaning how many days the bloom is offset from 'Red Charm'. (The detailed result chart shows a number such as - 20 days, or + 8 days by cultivar, for example). A more simplified version which you can see here converts the bloom comparison scale into weeks, not days. Different cultivars are assigned a week number, which can range from week 1 to week 7 with 'Red Charm' being a "week 4" cultivar in the middle.

I'm toying with the idea of extending the bloom time of my peonies, so I've been taking a look at this bloom time information. The range of bloom times has helped me realize that my peony season could be much longer than I ever imagined.

Would you believe that the study determined that the earliest-blooming cultivar on the list bloomed a whopping 37 days before 'Red Charm'? And the latest blooming one bloomed a stunning 39 days after 'Red Charm'? That's a 2.5-month spread! With information like that, I now feel empowered to transform my short peony season into a longer one.

One more note: If you are tight on space and don't have room to add multiple early, mid, and late cultivars, try searching for re-blooming plants. Where space is limited in my garden, I've planted re-bloomers such as irises ('Immortality' and 'Earl of Essex') and azaleas (look for the series called "Encore") to ensure that I get two seasons of bloom from one hard-working plant. More and more re-bloomers are being launched into the marketplace every day, a happy development that we can use to our advantage to keep our gardens blooming beautifully.

Hope you've enjoyed these tips!
Note: This is blog post number three in a four-part series on how I achieve continuous color in my garden. To read tip number one in my series about companion planting, click here. To read tip number two about containers, click here. To watch Garden Gate Magazine's video tour where I speak about my "4 C's" for flowery borders, click here.

Happy gardening,


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