It goes by the unglamorous common name of Tickseed. The botanical Coreopsis sounds much more appealing but, in fact, just glosses over a hard reality. This fancier name comes from the Greek koris, for bug, and opsis, for ‘like’, meaning the seeds of this plant look like bugs or ticks. Resemblances to insects aside, these starry flowers are still worth a look. Having established a bad rep for stealing the show one year and then disappearing the next, Coreopsis is back as one of summer’s perennial garden bedazzlers and this time you can rely on them.
This may come as surprising news to gardeners in southern Ontario and the mid-Atlantic region of the U.S. since we all share one thing that Coreopsis generally don’t like–clay soil. Thanks to plenty of new cultivars and hybrids as well as the findings from a three-year plants trial by researchers at the Mt. Cuba Centre, in Hockessin, Delaware, it’s easier to find a Coreopsis that fits your garden style and soil.
If you’ve never tried Coreopsis, there’s a compelling reason to try them now. Yes, they can be spectacular, work really well as a sparkling filler in a country garden, and provide summer-long colour in a naturalized area. But they’re also substantial supporters of beneficial insects. At the Mt. Cuba Centre’s Trial Garden, native plants and their related cultivars are evaluated for their horticultural value and their ecological value. Their latest report covers findings after three years of trialling 13 different perennial Coreopsis native to the eastern U.S. as well as their related cultivars and hybrids.
In addition to figuring out which Coreopsis grow best in this part of the world, the Mt. Cuba study used perennials, their cultivars and nine hybrid annuals to find out how Coreopsis supported pollinators and what kind. What was discovered is that each plant attracted a slightly different group of insects but all the plants proved to be supportive of beneficial insects including bees of all sorts, moths, butterflies, beetles and natural predators.
So which Coreopsis did the Mt. Cuba researchers find to be the best overall? Here are the top five highest rated, assessed for their habit, floral display, disease resistance, and longevity:
- Coreopsis palustris ‘Summer Sunshine: 4.9 stars
- Coreopsis tripteris ‘Flower Tower’: 4.7 stars
- Coreopsis tripteris ‘Gold Standard’: 4.7 stars
- Coreopsis verticillata ‘Zagreb’: 4.4 stars
- Coreopsis integrifolia ‘Last Dance’: 4.3 stars
To get the full report, click on this link: Research Report 2015 – Coreopsis for the Mid-Atlantic Region. You’ll find all the top performers (perennials and annuals) with lots of photos plus a whole lot of really useful information about hybrids, the “secret to hardiness”, tips about exposure, soil and maintenance, which plant attracts which pollinator and way, way more.
Confused about using natives vs. cultivars? For a good explanation of navitars (native plant cultivars), check out Navitars or True Natives?, a recent post from the excellent Garden Walk Garden Talk blog. In this post, you’ll also find some great photos of Mt. Cuba’s Native Garden which features a formal garden of natives and cultivated natives.
Here’s a sampling of eye-catching Coreopsis available in southwestern Ontario:
• Coreopsis verticillata Permathread™ ‘Red Satin’ is a new hybrid threadleaf Coreopsis with deep, bright red flowers and an orange centre, blooming from early through late summer. This plant has darker foliage than other threadleafs and has a tighter mounding habit, producing fewer rhizomes. Cut them back for a rebloom that can last until the first frost. Hardy to zone 5.
• If you like your flowers to come with a little symbolism, check out the Coreopsis verticillata Mayo Clinic ‘Flower of Hope’™. This hybrid (formerly called Coreopsis ‘Electric Avenue’) was renamed in honour of the Mayo Clinic Sesquicentennial in 2014 and is grown at each of the Mayo sites in Minnesota, Arizona, Florida, Iowa and Wisconsin. The well known American medical care and research service won’t be receiving any proceeds from the sale of the plants but does promote the benefits of horticultural therapy. As the Mayo Clinic website states, “We understand that enjoyment of nature can play a key role in the healing process.” In an article about the clinic promoting the flower, published on GreenHouseGrower.com, writer Laura Drotleff writes that “Bobby Saul of ItSaul Plants [which developed and held the patent for ‘Electric Avenue’] says in addition to its bright and sunny color and flower form, coreopsis’ ability to withstand severe weather extremes is the key reason Mayo Clinic chose the genus. The hospital system’s three main campuses are located in areas with severe weather extremes, from frigid cold in Minnesota to humid heat in Florida to dry heat in Arizona.” ItSaul Plants is an Atlanta-based company specializing in introducing new plants to the horticultural market.
• The variegated foliage of Coreopsis ‘Tequila Sunrise’ makes this compact plant a stand-out but I have to point out that it didn’t do very well in the Mt. Cuba trials. In fact, it didn’t last the entire three years. However, you might be luckier. If you are and it spreads by rhizomes, you can divide up the clumps in spring. This is a great plant when you’re looking to create a garden that looks a little on the wild side, but if you want to hedge your bets, use this as you would an annual. It’s not leggy and relatively short, reaching only a maximum of eighteen inches (45 cm), so this one makes a really nice container option as well.
• Coreopsis verticillata Sizzle & Spice™ ‘Curry Up’ is a Sheridan Nurseries exclusive in Canada. The bright yellow blooms have wide maroon centres. Hardy to Canadian zone 5, it has a uniformly rounded and compact growth habit growing up to 16 inches (40 cm). Sheridan also has exclusives in Canada for two other coreopsis in the Sizzle & Spice™ collection: ‘Crazy Cayenne’ has hot pepper red blooms and ‘Hot Paprika’ has deep velvety red blooms.
• Coreopsis ‘Moonbeam’ is a hybrid of C. verticillata and C. rose. It’s a grandaddy of the coreopsis cultivar family, having been introduced way back in 1965. Its lovely pale lemon flowers sit atop erect stems that create a finely textured mound. Plant this one next to a perennial with large, thick leaves to play up the airy foliage of this coreopsis. In the Mt. Cuba three-year coreopsis trials, this plant was rated 3.7 out of 5.
• Coreopsis Big Bang™ ‘Mercury Rising’ is a hybrid of Coreopsis rosea so, like its native cousins, this one should be impressively hardy. According to PerennialResource.com, the Massachusetts-based breeder has overwintered this plant where it has done well through that state’s typically nasty winters. The wine red petals are frosted in creamy white at the height of summer. For a couple more photos of Mercury Rising, check out this posting from Three Dogs In A Garden. Jennifer Connell of Huttonville, ON, writes a terrific gardening blog full of good advice and gorgeous photos. In this post, she shows Mercury Rising paired with Penstemon ‘Husker’s Red’. Stunning.
Want to go completely native? There are about 80 species of this genus all together, native to North America, Mexico, Central and South America. Though most of the North American natives are found in the U.S., up here in Canada, we have a few diehards, including:
- Coreopsis verticillata (Threadleaf tickseed) which grows wild in parts of Ontario and Quebec but it’s actually an introduced plant. It’s truly native in most states along the U.S. east coast.
- Coreopsis tripteris (Tall coreopsis) is native to parts of Ontario and Quebec as well. Among the tallest of the coreopsis, the stalks branch at the top, producing a single, brown-centred yellow flower on each. Despite its height, it’s considered wind resistant.
- In Canada, Coreopsis rosea (Pink tickseed) is only native to southwestern Nova Scotia though it’s more plentiful along the eastern U.S. seaboard. In Nova Scotia, it’s considered at risk due to the establishment of reservoirs for hydroelectricity, cottage development and off-road vehicles.
- Coreopsis lanceolata (Lance-leaved Coreopsis) is native to Ontario. You’ll find it growing in the wild in open woodlands, meadows and pastures. It’s considered one of the most common and easy to grow but, on the other hand, is not a reliable perennial.
Whichever species, cultivar or hybrid you choose, even if you only use it as a spectacular container plant, Coreopsis can light up your summer garden and make a lot of beneficial insects very happy.