Welcoming pollinators

With the first snowdrops blooming in the front yard, it’s time to get serious about this year’s growing season. What features should I be looking for when choosing flowers and plants to provide food for pollinators from spring through fall?

 

Monarch on New England aster

     Some useful plant families to start with are the asters (Asteraceae) and mints (Lamiaceae). I’m already growing several plants in the aster family, including purple coneflower (Echinacea purpurea), goldenrods (Solidago spp.), black-eyed Susans (Rudbeckia hirta), and New England asters (Symphyotrichum novae-angliae). These all have daisy-shaped flowers that are actually composites. 

Black-eyed Susans are composites of multiple tiny flowers

The “petals” are really ray flowers. The dark centers are made up of many tiny disc flowers.  This design makes visiting particularly profitable for insects. You’ll notice bees poking their proboscises repeatedly into the tiny openings. They’re harvesting nectar from each little flower.

    Sunflowers are in the same family, but I’ve mostly struck out with them. That’s because I can’t get them past the seedling stage. My squirrels seem to have a yen for sunflower sprouts. I’ve tried surrounding the seedlings in cylinders of wire screening, but the squirrels find a way to get at them before they can grow woody stems. 

Trying to protect seedlings from squirrels

I’m going to give it another try this year. I have a pop-up fabric shelter for protecting seedlings that’s 3 feet tall. I’ll try burying the edges in soil and see if sunflowers grown inside can make it past squirrel food size.

    I’d also like to grow Mexican sunflowers (Tithonia rotundifolia). This is a big annual with zinnia-like orange flowers and a wide round shape like a shrub. Sunflowers, Mexican and otherwise, have another benefit beside composite flowers. They also offer a stable landing pad for butterflies. A monarch with a 3-inch wingspan needs something sturdy to land on.

A sunflower makes a sturdy landing spot-photo Don Graham

    This is not to say that daisies are the only pollinator-friendly flowers. In the mint family, I’d like to try blunt mountain mint (Pycnanthemum muticum) again. One succumbed in a spot with too much competition. Mountain mints are reputed not to become invasive, unlike many other mints. The problem with bee balm (Monarda spp.) and giant hyssop (Agastache spp.) in the same family is their tendency to spread aggressively. I moved Agastache ‘Blue Fortune’ from lean sandy soil near the fish pond to a richer bed, and now I have to pull out wheelbarrows full every year.

Hoverfly on Agastache 'Blue Fortune'-photo Benh LIEU SONG

    I’ll also draw pollinators with compound flowers such as those of alyssum (Lobularia maritima), sedum (Sedum spp.), and swamp milkweed (Asclepias incarnata). These all feature clusters of small flowers that attract lots of insects.

Alyssum has a sweet scent and draws lots of pollinators

    I’d like to grow foxgloves (Digitalis spp.) again. Their attractive spires have nectar guides, in the form of freckles, that attract bees and butterflies. These are flower markings that lead pollinators to the nectar, like airport runway lights, simplifying their search for food. I’m fond of the variety ‘Foxy’, which blooms the first year from seed. I might grow it again to save energy for bees. This is a hopeful time in the gardening year.

Foxglove freckles guide bees to nectar

Wedding white

Dear friends,
I apologize for infrequent posts. I’m absorbed with a happy event, my son’s wedding next weekend. I’ll be back with another post in June. Here’s something I hope you’ll enjoy for the end of May:

White flowers signify innocence, purity, honesty, perfection--and weddings. Whatever the occasion, May’s white flowers are especially beautiful. 

    Before we assume that flowers are white for a biological purpose, we have to bear in mind that from the plant’s point of view, human vision is beside the point. Flowers evolve mostly to attract pollinators. 

    Bee vision, for example, differs from ours. Bees can’t see at the red end of the visible light spectrum, but they see ultraviolet light that’s invisible to us. A flower that looks white to us could show a bee ultraviolet runway stripes (nectar guides) or bullseyes to mark the landing area, holding up a sign that says “Get your nectar and pollen here!”
 
 

Visible nectar guides--stripes on this iris--guide bumblebees to pollen. Photo by Al Schneider

    Each of my white flowers has a different strategy for getting its flowers pollinated and reproducing itself.

    Sweet woodruff (Galium odoratum) is a hermaphrodite pollinated by bees, flies, or itself—no wonder it spreads so fast. 

    Double-file viburnum (Viburnum plicatum var. tomentosum ‘Shasta’) has been fooling visitors this spring into thinking it’s a dogwood because of its horizontal rows of glowing white flowers. These attract insects and humans first with larger, sterile flowers that resemble the “petals” on flowering dogwoods (in fact those are adapted leaves called bracts).

The inner fertile flowers of the viburnum open a few days later.  

    Lily-of-the-valley (Convallaria majalis) is flowering profusely this week. Last year must have been a good one for this plant, because as its leaves emerge this spring, I’m finding it has expanded into new territory. The tiny bells on its flower stalks are pollinated by honeybees and bumblebees.

Each lily-of-the valley needs to cross with a genetically distinct plant to make fruit, one red berry per plant. But anyone who lives with this determined shade grower knows it does plenty of vegetative spreading even without fruit.

    The flowers of dwarf fothergilla (Fothergilla gardenii) have both male and female parts but no petals. I read that they’re pollinated by honeybees. Offering such easy access to nectar, they must attract other insects too. 

Bottlebrush flowers of dwarf fothergilla

    Bleeding heart, a member of the poppy family (Papaveraceae), offers pollen but not nectar to visiting insects. 

White bleeding heart, Dicentra spectabilis 'Alba'

Once the seed develops, bleeding heart has an interesting method for spreading it around. Each seed is attached to an elaiosome, a white fleshy blob rich in lipids that ants like to eat. 

Bleeding heart seeds with attached elaiosomes

Ants carry the seed back to their anthills and eat the elaiosome without damaging the seed. In return, the seed gets a free ride to a location farther from its parent plant than it could otherwise travel.