Bulbs Attract Bees & Beneficials
Beyond providing an extra splash of color for our own enjoyment, there are some compelling reasons to add spring- and summer-flowering bulbs to your landscape. Doing so helps to bolster biodiversity — something we’re increasingly losing thanks to competition from invasive plants such as kudzu and winter creeper. Land development has also taken a bite out of natural forage opportunities for insect pollinators.
By incorporating early- and late-bloomers into your garden beds — or even throughout parts of your lawn — you can at the very least help to extend what’s on the menu for area honeybees and other beneficial bugs. What’s more, depending on the types of flowering bulbs you choose, you may be able to give them a much-needed nutritional boost during periods when nectar and pollen are harder to come by.
Failing Flowers?
Since the mid 1990s, researchers from around the world have investigated the effects of warming temperatures on plants and flowers. Temperature changes have been shown to influence the amount of nectar individual flowers produce. Heat stress can negatively affect nectar quality, pollen performance and more.
Warming temperatures and changes in weather patterns have also contributed to the success of many invasive plant species. These invasive plants, in turn, are crowding out many of the native plants on which some beneficial insects have come to rely. With these extra challenges in mind, mixing in certain types of flowering bulbs (as well as flowers which grow from rhizomes, corms and tubers) may become increasingly important for attracting and sustaining pollinators.
Types to Try
If you hope to provide real value to honeybees and native, beneficial insects, keep in mind that not every flower bulb variety is created equal. As is the case with all kinds of flowers, when plant breeders focus their attention on selecting for bloom size, petal color, disease-resistance and so on, other traits — such as the amount and quality of nectar, for instance — can suffer. That’s why some older (and plainer) varieties may be better choices than fancy new cultivars when you’re specifically catering to pollinators.
Hoping to determine which bulbs had the most staying power and the ability to attract area pollinators, University of Arkansas researchers grew 30 early-spring flowering bulbs within a couple types of warm-season turf grass. Over a three-year period, they investigated low-growing flower varieties such as Grecian windflower (Anemone blanda), winter aconite (Eranthis hyemalis) and spring starflower (Ipheion uniflorum), among others.
“As a group, the crocus and grape hyacinths
were most successful at both persisting and providing a pollinator habitat,” the researchers noted. Honeybees were particularly drawn to the crocus cultivars “Golden Yellow,” “Blue Pearl,” “Cream Beauty,” “Spring Beauty” and “Remembrance.”
As for grape hyacinths, good performers included Muscari armeniacum and Muscari neglectum, as well as the specific cultivars “Valerie Finnis” and “Mount Hood.” The study was published in the journal HortScience in 2019.
Notable Natives
Although you may not necessarily find them at every big-box store or even in your favorite local nursery, native bulbs and corms are also worth seeking out. There is no need to dig up and store them over the winter, and they’re also more likely to spread on their own.
Another benefit is that they’re great for supporting native bees. So, depending on your local climate, you might consider adding some of the following natives along with those crocuses and grape hyacinths. (Psst! If you can’t find any suppliers in your region, try one of the specialty native plant retailers online.)
• Blue Flag Iris (Iris versicolor) — Hardy in
U.S. zones 3 through 9, the blue flag iris puts out its blue-violet blooms beginning in early to mid-spring. Blue flag irises don’t mind “wet feet,” so plant it in moist, loamy soil. This native iris typically grows a little over 2 feet tall.
• Camas Lily (Camassia quamash) — Sometimes called the “wild hyacinth,” this late spring bloomer is hardy in zones 3 through 8 and is suited to average-to-moist, loamy soil. Camas lilies put out spiky, bluish-purple flowers and are just under 2 feet high at maturity.
• Louisiana Iris (Iris louisiana) — Reaching about 3 feet tall, Louisiana irises are larger and showier than blue flag irises, and they perform best in average to moist, loamy soil. Blooms appear in early summer with varying colors depending on the Louisiana iris variety you choose. Types such as “Bold Pretender” feature pretty, pinkish-red petals and are hardy from zones 4 through 9.
• Blazing Star (Liatris spicata) — Hardy in zones 3 through 9, blazing star can reach 2 to 4 feet tall and sets its spiky, purple blooms in mid-to-late summer. Blazing star thrives in slightly loamy, well-draining soil.
• Nodding Onion (Allium cernuum) — Hardy in zones 3 through 8, nodding onions prefer average-to-dry, loamy soil and full sun. Typically, they reach a little over a foot tall and will put out heads of tiny lavender flowers in mid-summer.
• Michigan Lily (Lilium michiganense) — This
early-to-mid summer bloomer is hardy in zones 3 through 8 and prefers moist, loamy soil. Michigan lilies will grow up to 5 feet tall and put out orangey-red flowers with sharply curving petals.
• Wood Lily (Lilium philadelphicum) — Also known as the “prairie lily,” wood lilies are hardy in zones 3 to 7 and look a lot like tiger lilies; however, wood lilies are just a foot tall at maturity. Watch for blooms in mid-to-late summer.
The Best Start
Whether you’re buying from a brick-and-mortar retailer or a specialty seller online, choose bulbs that have been nursery-propagated rather than sourced from the wild. This is especially important if you are purchasing some of the more difficult-to-find native bulbs and corms.
And, before you plant, examine each bulb for signs of damage from pests or disease. Ideally, bulbs should feel solid with no significant cuts or squishy spots.
When planting crocuses, grape hyacinths and other spring-flowering bulbs, be sure to get them in the ground at least a few weeks before your average first frost. As for summer- or fallblooming bulbs? Most of these are planted during spring when the soil is easily worked and the danger of frost has passed.
Once it’s planting time, use the following steps (and corresponding photos above) to ensure that your bulbs have optimal growing conditions and adequate rodent protection, too.
STEP 1: Use a trowel or bulb planter to dig one hole per bulb or corm. Follow nursery package directions for planting depth. (If directions aren’t available: Most bulbs should be seated in a hole that’s at least twice as deep as the bulb is wide.) Temporarily set aside the excavated soil.
STEP 2: Add aged compost to the bottom of the planting hole. Mix some extra compost in with the excavated soil you set aside in the previous step. (You may be able to skip amending with compost if your planting bed is already nutrient-rich and well-draining.)
STEP 3: Fashion a section of hardware cloth or chicken wire into a small cage. (For hardware cloth, use heavy-duty tin snips. For lightweight chicken wire, a simple pair of wire-cutting pliers should do the trick.) Place the bulb inside its protective cage and then carefully close the cage’s top. When buried, the cage should keep chipmunks, mice and other critters from damaging — or devouring! — your bulb.
(Incidentally, once you notice plant leaves begin to show in the spring or later in the summer, you’ll want to dig around until you’ve exposed the top of the bulb cage. With the caged bulb still firmly planted in the ground, gently make a few bends or cuts in the cage’s top to
make more room for the top of the growing plant. Then, replace the soil around the newly freed plant top.)
STEP 4: With the bulb tucked safely inside, bury the cage inside the hole. Remember, your bulb’s planted depth should be at least twice as deep as the bulb is wide. The small corms of crocuses, for instance, are best planted at around 3 inches deep. Much larger bulbs such as tulips should be planted 5 or 6 inches deep.
STEP 5: Cover the caged bulb with your soil-compost mixture. This will act as a slow-release fertilizer, delivering a supply of all-natural nutrients and micronutrients for more robust roots, leaves and, ultimately, flowers. (Optional: for added protection from digging critters, disguise any freshly disturbed areas with a couple of inches of dried leaves, pine needles or wood chips.)
STEP 6: If the soil is dry, go ahead and water in the bulb. Just take care to avoid waterlogged soil, as this can cause some newly planted bulbs to rot.
Susan M. Brackney is a freelance writer and the author of Plan Bee: Everything You Ever Wanted to Know About the Hardest-Working Creatures on the Planet.