Adding Bulbs to Fill in Borders By Becky Heath

Integrating bulbs with herbaceous perennials and shrubs can extend a garden’s flowering season and create new color combinations.
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Photo credits: Brent and Becky Heath

As fall approaches, the siren call of bulb catalogs accumulated over the summer comes to a crescendo. If you have a new garden with oodles of space to fill, then you have the luxury of crafting a plan to blend bulbs with herbaceous perennials and shrubs to create a harmonious, seasonally changing symphony of colors, textures, and shapes.

But even if your garden, like mine, is already well established, you can always find a little more space to tuck some bulbs within, among, around, or under other plants to create a complementary effect and that amazing spring payoff. Gardens are not static, after all; they are constantly evolving as plants outgrow their space or die and have to be replaced. Gardeners’ tastes and interests change over time, too, in response to new trends, changing conditions, and an ever expanding plant palette.

FINDING SPACE

So how do you add bulbs to an already existing garden? The best answer is: carefully. But it isn’t impossible, and it’s actually fun to test out new color combinations and even create changing color displays from year to year.
There are several approaches to combining bulbs with herbaceous perennials, shrubs, and trees.

Choosing combinations that will bloom at the same time creates the biggest impact, like the finale of a fireworks display. Combining plants so that they bloom sequentially with a slight overlap, however, keeps a garden pleasing to the eye for the longest time. With careful selection, you can create a display where something is in bloom the entire season.

Planting for maximum effect is important, but it’s even more critical to match bulbs and plants with similar cultural needs. After all, if your bulbs don’t flourish, then you won’t get much of a show. So assess your site for exposure to sun or shade, and check the soil to determine how wet or dry it stays as well as its acidity or alkalinity. And, of course, be sure your bulbs are hardy and heat tolerant in your region. If you live in a warm-weather region, you may have to pre-chill your bulbs.

Herbaceous Perennials

Combining bulbs with herbaceous perennials and low-growing shrubs is a great way to mask the maturing foliage of the spring bulbs after they have flowered. The colors of the early-blooming perennials are what attract your attention—and that means you’ll be less tempted to cut down the bulb foliage too early. Remember, after bulb flowers have faded, the foliage needs six to eight weeks of sunlight to help replenish the energy for the following year’s bloom.

Some of the best herbaceous perennials to help camouflage the maturing foliage of spring bulbs include daylilies (Hemerocallis spp.), peonies, hellebores, catmint (Nepeta 5faasinii), and hostas.

For example, in our Gloucester, Virginia, garden, my husband Brent and I have a two-square-foot area that has white daffodils emerging through the dark burgundy foliage of a peony in mid-spring. Later, when that peony matures, masking the daffodil foliage, its dark green leaves and rose-pink flowers look beautiful with blue Dutch irises coming right up through them, blooming at the same time. Actually, this combination was quite serendipitous. We planted the daffodils and Dutch irises one year, and the next season we planted a peony on top of the bulbs, forgetting they were there.

Most spring-flowering bulbs prefer to be dry and cool in the summer, when they are dormant. The perennials planted in the same bed as the bulbs make useful neighbors to the bulbs by helping to soak up the moisture from the summer thunderstorms as well as shading the bulbs during the hottest summer months. That is just one more reason for mixing bulbs, perennials, and annuals in the same border.

As perennials grow, their branches and foliage often spread out, covering part of the bed’s surface, even though their actual root bases cover much less territory. Often you can carefully lift the foliage of a perennial to make space to dig a hole for some bulbs. In most cases, the bulbs will have no problem coming up through or around the perennial—or may even bloom while it is still dormant.
Where there is very limited garden space, you can still have a long-lasting bulb display if you think “vertical” and take advantage of staggered bloom times. You can plant tulips or lilies eight to 10 inches deep, then above them place daffodils, hyacinths, or alliums at about six inches. Smaller early-blooming bulbs—such as crocuses, anemones, and dwarf irises—can even be planted in the top three inches.

Around Trees and Shrubs

Flowering trees are one of the most effective companions for bulbs. For example, planting bulbs in front of a weeping cherry or a flowering plum helps the garden to be seen from great distances and is well worth the effort. Choosing bulbs with flowers that echo the color of the tree’s flowers is one attractive design idea. For a different visual effect, try bulbs whose flowers offer an appealing contrast to those of the tree.

The area around the base of a tree is the perfect place to plant small bulbs such as crocuses, grape hyacinths (Muscari spp.), squills (Scilla spp.), or miniature daffodils. The tree offers the bulbs some added protection from severe weather during the winter and early spring, and the bulbs can be planted shallowly so they won’t damage tree roots. It’s a great symbiotic relationship and attractive to boot. Some other effective small flowering trees for this purpose are crabapples, pears, dogwoods, redbuds, magnolias, and serviceberries (Amelanchier spp.)—or shadbushes, as we call them here in coastal Virginia.…

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