Gazette Gardener: Cultivating winning combos
Cornell researchers test bulbs and perennials to find ideal pairings for spring garden
This is a busy time of year for gardeners. Not only are we tidying up from this season, but we are starting to think ahead to next season and the spring-blooming bulbs.
What will we grow? Are there any spots in the garden that need an early season pick-me-up? Is there a way I can lower the amount of necessary maintenance and still add lots of early bloom? What will look best together? What will best hide the dying foliage once the bulbs are finished blooming?
While we thought we were alone in our flower beds with these musings, evidently we were not. Researchers at Cornell University took their horticulture know-how, combined it with an aesthetic eye and, like true scientists, put it to the test by planting various pairings of bulbs and perennials.
Professor William B. Miller, who is director of the university’s Flower Bulb Research Program, led the Cornell team. “The idea of pairing bulbs and perennials to achieve multiple goals is so desirable that we felt it deserved more than an anecdotal approach. We created an objective study to document what works and what doesn’t in a typical spring garden,” he said.
The combination trials were designed to achieve four goals:
1. To look at how early bulbs help extend the bloom season in the garden.
2. To explore how perennials might best be used to mask the dying foliage of post-bloom bulbs.
3. To consider leaf texture as a design element.
4. To examine the various roles color plays in creating successful combinations.
The Cornell scientists evaluated the plantings for their overall performance and benefits, and did not necessarily look for combinations that bloomed simultaneously. They focused on combinations that worked. The series of trials covered four seasons at the university’s Ithaca trial grounds, which are in USDA hardiness zone 5, same as the Capital Region.
Here’s a sneak peek at 12 of their top performing combos, with what the researchers observed in their own words:
-- Allium karataviense “Ivory Queen” with Aster macrophyllus — The allium leaves match the aster foliage nearly perfectly, allowing for the blooms to show with no worry of unattractive foliage. The two plants grow at the same rate and the blooms are still visible.
-- Anemone blanda “White Splendour” with Rheum palmatum “Atrosanguineum” — The fine white flowers of the anemone contrast well with the dark, coarse foliage of the rheum. The anemone blooms before the leaves of the rheum get too large, and then the rheum grows to cover the old foliage of the anemone. Rheum would be a good companion for many bulbs because of its large leaves.
-- Hyacinthus “White Pearl” with Rheum palmatum “Atrosanguineum” — Just as the rheum contrasted with and then covered the anemone, it does so for the hyacinth. This combo could be even better if a multiflora or “looser” white hyacinth were used.
-- Hyacinthus “Jan Bos” with Penstemon “Husker Red” — The emerging penstemon leaves are dark purple just as the hyacinth is blooming, creating a nice color scheme. It seems as though many cultivars of hyacinth can be combined with Penstemon “Husker Red.” The penstemon is slow enough to allow the hyacinths to finish blooming and re-energize their bulbs, and then takes over before the foliage becomes unsightly.
-- Ipheion uniflorum “White Star” with Potentilla argentea — The interesting texture of the newly emerging potentilla leaves makes a complementary surrounding for the blooming ipheion. The potentilla then grows tall enough to sufficiently cover the browning leaves of the ipheion, making a useful combination.
-- Narcissus “Fortissimo” with Papaver orientale “Turkenlouis” — An excellent functional combination whereby the narcissus flowers slightly above the developing poppy leaves. The leaf texture contrast between the narcissus and papaver make for an interesting mix early on, and the fast growth of the papaver covers the narcissus foliage quickly. Any combination of poppy and similarly sized daffodil would work. The poppy flowers after the daffodil, so color is not an issue.
-- Narcissus “Ice Follies” with Pulsatilla vulgaris “Papageno” — This combination shows contrasting foliage texture, simultaneous blooming that complements both plants, and perennial foliage cover after the bulbs are finished for the season. The yellow center of the pulsatilla and the corolla of the Ice Follies are a great color echo. Also, the fuzzy and airy seed heads of the pulsatilla camouflage faded narcissus flowers.
-- Narcissus “Pink Charm” with Cimicifuga ramosa “Brunette” — The foliage of the cimicifuga complements the narcissus foliage and flowers early in the season. It also grows large enough to mask the browning daffodil leaves. This combo would be especially excellent if narcissus were interspersed more evenly.
-- Narcissus “Salome” with Phlox paniculata “Bill Baker” — This combination illustrates the use of bulbs with perennials to extend the bloom season. After the narcissi are finished, the phlox explodes with blooms, masking the bulb foliage. This combo would work with many narcissi and probably also with early tulips.
-- Narcissus “Slim Whitman” with Achillea filipendulina “Gold Pallette” — The leaf texture of the emerging achillea offers contrasting texture, adding to the interest of the spring garden. The achillea foliage grows tall and thick enough to hide the fading narcissus foliage.
-- Tulipa “Ballade” with Geranium “Mayflower” — The height of the purple-hued tulip at bloom and the early geranium foliage makes the tulip blooms look as if they are floating in a sea of green. Later, the geranium’s foliage and purple flowers mask the fading tulip leaves.
-- Tulipa “Don Quichotte” with Geranium “Claridge Druce” — The blooming of the tulip and the growth of the geranium coincide perfectly. A functional combo, with the geranium foliage working to mask the tulip leaves as they senesce. The pink color of the tulip is echoed by some purpling of the geranium, caused by cool spring weather. Another combination, “Don Quichotte” with Geranium pratense “Splish Splash” is similar.
You will find more information on the Cornell website with suggested combinations of perennials with tulips, narcissi, crocuses and more. There are also tips and how-to sections and even accounts of combinations the researchers found to be less than successful. If you’re curious, go to www.hort.cornell.edu/combos.