Are Bulbs Good for Pollinators?

My volunteers and I have been spending many hours this fall planting daffodils and tulips around the Arboretum grounds. All told, we will have nearly 800 new blooming bulbs coming up next spring, down a bit from the 1000 we planted last year.

One afternoon my colleague Brad Guhr posed an important question:
“Are bulbs useful to spring pollinators?”

We all love the aesthetics of fat yellow daffodils and spritely crocus, but I had never considered whether they served an ecological purpose. Supposing (incorrectly) that most bulbs I order are native to the Netherlands, what good would they be to our local pollinator population?
I have now been down the rabbit hole of research and will summarize here how bulbs affect pollinators, which bulbs attract them and proper bulb planting technique.

Tulip humilis (aucheriana) is a wild-type tulip that does well in gardens and meadows alike.
By Bernd Haynold – selbst fotografiert – own picture, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4767022

Bulbs and Bugs

Long before people started admiring their blooms, most of our favorite bulb flowers were being visited by pollinators. Such is not the case for today: modern hybrids selected for the biggest bloom and brightest color sometimes become less useful to pollinators. Flowers that have been distorted too far from their original form may have less nectar or be entirely sterile, rendering them useless as a food source. Hybridization can also sacrifice the flower’s strong scent, leaving aroma-sensing pollinators (like nocturnal moths) lost without lunch. As humans try to improve flowers for our own eye, we  inadvertently disrupt their role in nature. Insects and flowers have an important relationship directly related to the flower’s form. If it changes drastically, certain insects may no longer be able to reach the nectar. Because of this, avoid buying highly modified ‘double’ and ‘triple’ bloomers or extra-petaled flowers that will likely inhibit a pollinator’s ability to feed.

Narcissus poeticus, Public Domain, https://commons.wikimedia.org/w/index.php?curid=907

Best Bulbs

Though we may associate the bulb trade with Holland, the native range of daffodils is the Iberian Peninsula and tulips grow wild in Turkey and Central Asia. Crocus were originally native to southern Europe, the Middle East and western China. There are some bulbs native to North America, such as Claytonia virginica and Mertensia virginica as well as the trout lily, but they are too often upstaged by fancy exotics. This link offers great options for North American native bulbs that will benefit you and the ecosystem. If you aren’t ready to give up your tulips and daffodils, never fear! By choosing unhybridized species, the flower retains its pollen and nectar, supplying much needed early spring feeding for hungry pollinators. Crocus, species-variety Tulips and Muscari all are well-loved by hungry bees waking up from their long hibernation as well as wild type daffodils such as Narcissus poeticus or N. jonquilla.

A bee visiting a purple crocus flower.
CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=660234

Claytonia is a lovely North American native. By Dcrjsr (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

Planting Tips

The first step to proper planting is identification – is what you are holding truly a bulb? Corms, tubers, rhizomes and true bulbs all fall under the category “geophyte” (a perennial that stores its food underground). Many rhizomes would not like to be buried as deep as a bulb but corms can be treated much the same. Sorting out the technicalities will ensure correct planting and big blooms!
When planting true bulbs, depth is essential. In general, plant bulbs 2 or 3 times as deep as its height. Example: a 2 inch tall daffodil bulb should be planted 6 inches deep. Digging too shallow is better than planting too deep since many bulbs have contractile roots. Over time, these specialized roots will pull it down to optimal depth. Planting root side down/pointed side up is always best, but if the bulbs are too odd-shaped to tell, plant them sideways to be safe. Thanks to geotropism, a plant’s ability to sense gravity and grow accordingly, they will eventually right themselves.

Bees love Fritillaria meleagris, a dainty and unique bulb native to Europe. By Пономарьова Алевтина (Own work) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

So, after much scouring of the internet it seems there is no straightforward answer to Brad’s question. Many highly hybridized bulbs do not benefit pollinators, but other heirloom or species varieties certainly do. To benefit early spring pollinators in your bulb garden, install a few North American species or try to find unhybridized varieties that retain their full species name and their ecological importance. Get out your sweaters and garden gloves, now is the time to get digging!

Six Ways You Can Help the Pollinators

Did you know that this week is National Pollinator Week (June 15 – June 21)? Whether it is with bees, butterflies, birds or beetles, pollinators are extremely important and provide valuable services.

Three-fourths of the world’s flowering plants depend on pollinators to reproduce.  Think of all the food crop production that would not be possible without the help of pollinators.  We rely on these small, seemingly insignificant pollinators for the food we eat.  If they are so valuable, then they are certainly worth recognizing and saving.

Here are six ways you can help increase declining populations of pollinators, including bees and monarchs:

1. Plant Pollinator-Friendly Plants

Certainly, milkweeds are the best wildflowers for attracting monarchs to your yard.  We saw it this morning as we walked the arboretum – we found three caterpillars munching on the milkweed leaves.  Not only that, but every blooming wildflower was covered with a host of insects.  The wildflowers are the buffet. (Peruse our native plant list and sample landscape designs for some inspiration.)

Photo by Brad Guhr

Monarch butterfly on Asclepias incarnata, or swamp milkweed – photo by Brad Guhr

 

2. Plant for a Succession of Bloom

I recommend planting wildflowers that bloom at different times of the year.  A mixture of wildflowers coming into bloom and going out of bloom throughout the year provides a ready food source.  This approach mimics the natural prairie and the changing seasons.

Sulphur on Cardinal Flower

Cloudless sulphur on Lobelia cardinalis, or cardinal flower – photo by Brad Guhr

 

3. Provide Habitat

Layer trees and shrubs along with wildflowers and grasses.  These plants provide shelter from the wind along with nesting sites and food for birds, butterflies and bees. Even a small garden can have a tremendous impact.

Bumblebee on Echinacea purpurea - photo by Janelle Flory Schrock

Bumblebee on Echinacea purpurea, or purple coneflower – photo by Janelle Flory Schrock

 

4. Provide Water

We all need water for survival.  Pollinators need it too.  A clean source of water such as a birdbath, basin, or hollow stone is enough water for pollinators.  These features also provide landing spots so that pollinators have a perch. Here are some great plants to complement your water feature.

 

5. Reduce Chemicals

There is growing research on the detrimental effects chemicals have on pollinators.  Any time we can reduce or eliminate the use of chemicals in the landscape, we are impacting wildlife in a positive way.  Allow insects to control unwanted pests.  Be willing to accept a few damaged plants, knowing that by not spraying you are saving much more in the long run.

HummingbirdMoth on liatris

Hummingbird moth on Liatris pycnostachya, or Kansas gayfeather – photo by Janelle Flory Schrock

 

6. Learn About the Plight of Endangered Pollinators

There is so much to learn about each type of pollinator.  What do they need?  When are they out in the garden?  What do they need to complete their lifecycle?  Where do they migrate or how do they overwinter?  We have so much to learn about these important insects. (One good resource for this is this book, by Heather Holm, which we often carry in our gift shop. And, of course, MonarchWatch.org is a great resource.)

 

When it comes to supporting the life cycle of pollinators, you can be part of the solution.  Native wildflowers are the best option to help them prosper.  You will be amazed when you introduce just a handful of wildflowers to your landscape.  If you plant them, pollinators will come.