Pairing bulbs with perennials

Published 5:00 am Tuesday, October 19, 2010

The conversation on bulbs usually ends something like this:

“Oh, I love bulbs but hate the look of dying foliage, so I don’t bother to plant them.”

What a lost opportunity for that first burst of spring color.

Back in the dark ages of gardening, the foliage of bulbs, after the flowers died, was cut off in a fan shape or bent over and tied with raffia.

Then came the dawn of gardening magazines with technical information being shared by university horticultural experts, plant specialists and plant developers.

In no time at all, we started to become smart gardeners. Given reasons why we should or shouldn’t continue with old procedures, we learned to change our ways. Now we have an even faster method of exchanging information on the Internet. We just need to be sure that it is reliable.

Sally Ferguson, director of the Netherlands Flower Bulb Information Center/North America, e-mailed me a seasonal portfolio of information that included the results of a Cornell University research project.

Cornell professor William Miller, director of the university’s Flower Bulb Research Program, worked with a team researching successful bulb and perennial combinations.

The project was tested over four seasons and took place at the university’s Ithaca, N.Y., trial gardens, which are in USDA Zone 5. The combination trials were designed to meet four goals:

1. Look at how early bulbs help extend the bloom season in the garden.

2. Explore how perennials might best be used to mask the dying foliage of post-bloom bulbs.

3. Consider leaf texture as a design element.

4. Examine the various roles color plays in creating successful combinations.

The experiment list includes 44 pairings. I chose to include here the bulbs and the perennials we would be most familiar with, but may not have considered combining.

Research results that worked well included:

• Anemone blanda (“White Splendor”) with Rheum palmatum (rhubarb “Atrosanguineum”). Rhubarb would be a good companion to many bulbs because of the large leaves, plus the texture and the stalk color of the emerging plant.

• Chionodoxa (“Glory-of-the-Snow”) with Siberian bugloss.

• Penstemon (“Husker Red”) was recommended as a pleasing combo with hyacinths. The dark purple leaves of the penstemon emerge as the hyacinth is blooming and are slow enough to allow the hyacinths to finish their cycle before they take over to conceal the dying foliage.

• Hyacinths were also combined with Lychnis chaledonica (“Maltese Cross”).

• Scilla with geranium sanguineum. The geranium would be the perennial variety, not the coastal or Martha Washington types that appear in garden centers in late March.

• Narcissus (“Bellsong”) with hosta (“Sum and Substance”).

• Narcissus (“February Gold”) with potentilla (“Miss Wilmot”).

• Narcissus (“Fortissimo”) with Papaver orientalis (red poppy “Turkenlouis”). The contrast of the leaf texture between the daffodil and the poppy makes for an interesting mix.

• Narcissus (“Gigantic Star”) with Achillea millifolium (yarrow “Summer Pastels”).

• Narcissus (“Ice Follies”) with Pulsatillia valgaris (pasque flower “Papageno”). This combination shows contrasting foliage texture, and in our climate, we hope, it would bloom simultaneously for the full benefit of the combination. The fuzzy and airy seed heads of the pasque flower will camouflage the dying daffodil flowers.

• Narcissus (“Mt. Hood”) with nepeta (catmint “Six Hills Giant”).

• Narcissus (“Salome”) with Phlox paniculata (summer phlox “Bill Baker”). This combination would work with many daffodils and probably with tulips.

For those able to grow tulips from bulb to bloom without the deer snipping them, the research team offers some interesting combos. Since there is a broader color selection available with tulip varieties than daffodils, more care should be given to the paring of the colors. The goal would be to either choose a bulb and a perennial that would echo each other’s color, or go for a really dramatic effect.

Perennial geraniums would be useful if you planned to echo colors, as many varieties have interesting leaf and bloom veining color. A dramatic combo of leaf color and texture would be a purple late-blooming tulip with Stachys byzantinal (“Lamb’s Ear”).

If you are interested in viewing the entire research collection, visit www.hort.cornell.edu/ combos.

Paperwhites

While perusing the Cornell horticultural site, another research project caught my eye: “Pickled Paperwhites.”

Paperwhites are the popular bulb to force for the holiday season. Paperwhites are usually grown in water and pebbles, and are notorious for growing tall and leggy, flopping over just when they are at their peak of bloom.

Through an inquiry from a journalist — does alcohol stunt the growth of paperwhites? — a new research project was born. Miller (the bulb researcher) conducted a study and concluded that growing paperwhites in a 4 to 5 percent solution of alcohol is an excellent growth regulation technique. When grown in 5 percent alcohol, plants are about half the height of plants grown in straight water. Given that most liquors are 40 percent alcohol, this is equal to one part booze to seven parts of water. Gin, vodka, whiskey, rum, tequila and schnapps are all equally effective as long as they are given at the same alcohol concentration (realizing that liquors can come in different strengths). Beer and wine are not recommended as they kill the bulbs.

I couldn’t help but wonder if this question was the result of a cocktail party and someone dumping their drink in the vase of growing paperwhites. However it came to light doesn’t matter; we all benefit from the information.

While you are bulb shopping, think about potting some for indoor bloom. Use a potting mix or a bulb planting mix rather than the native soil. Paperwhites are the most popular bulbs to force at the holidays, and they are often forced in water as opposed to soil. There are three narcissus suggested for successful forcing: “Abba,” “Bridal Crown” and “Earlicheer.” Spacing can be closer than in the ground; bulbs can almost touch. Set the container on an outdoor porch or patio. Check regularly for dryness by sticking your finger into the soil up to the second knuckle. If it comes out dry, water.

Bring inside after buds form. Starting in October should give you blooms by the holiday season — at least that is what it says in the fine print. This is on my list to try. One advantage over the paperwhites is that the narcissus bulbs can eventually, when the weather allows, be planted to the garden.

Better together

A team at Cornell University has been researching combinations of bulbs and perennials. The project aimed to discover pairings that allowed for early-blooming bulbs and later-blooming perennials to provide cover for one another, as well as combinations with colors and texture that worked well together. Below are three pairings that worked well.

Narcissus (“Salome”) with Phlox paniculata (summer phlox “Bill Baker”).

Anemone blanda (“White Splendor”) with Rheum palmatum (rhubarb “Atrosanguineum”).

Narcissus (“Gigantic Star”) with Achillea millifolium (yarrow “Summer Pastels”).