Friday, January 24, 2020

Project Swallowtail!

Giant Swallowtail - Gordon Robertson
Today  it's my pleasure to pre-announce Project Swallowtail!
Zebra Swallowtail - Megan McCarty
This initiative to increase pollinator habitat in a large chunk of downtown west Toronto is led by WWF Canada in collaboration with many other groups, including my own Horticultural Societies of Parkdale and Toronto.

Blue dots on the map show just some of the gardens and Block Ambassadors already included.

Kathy's Garden, Stanley Park - Clement Kent
What are we going to do? Simply, we're going to help your block get a much higher density of pollinator-friendly plants over the next several years, with the goal of greatly increasing pollinator numbers and health. We want to do this in a way that allows birds, butterflies, and bees to move
freely for park to park and home to home. And, we'll be using some locally rare but very visible species such as the swallowtail butterflies shown above to make it easy to see when your block has become a hotspot of pollinator diversity.

LEAF Young Urban
Forest Leaders
We're also going to involve local kids and young adults in several ways. Mobile apps to help them identify plants and pollinators will be rolled out, with awards going to young pollinator experts.

Perhaps your block will become part of a neighbourhood where collaborator LEAF helps young naturalists learn about, map, and plant an urban forest?

Or maybe your or your neighbours' kids will go to High Park to learn about native plants and animals from H.P. Nature?

Block Ambassadors

Would you like to help us enrich your block for pollinators? We need Block Ambassadors! You don't need to be a gardener or a naturalist - just someone who likes talking with neighbours and promoting this project. We'll ask you to donate a few hours a month of your time to helping your neighbours get the plants and the help they need. You can reach us at [this address will change very soon now!] See our map of ambassadors in your vicinity.


Tuesday, November 26, 2019

Which flowers attract the most pollinators?

People often ask me "Which plants are best for pollinators?" There's no perfect answer, but I usually urge people to plant native perennials. But, is this right from the BBB (Birds, Butterflies, and Bees) point of view?

Professor Christina Grozinger
The perfect pollinator plant depends a lot on where you are planting it. A 20th floor balcony demands different choices than a back yard flower bed.  Experienced gardeners are good at helping you decide which plants will thrive in your location, but when we throw in the BBB perspective there is simply less expertise out there.

That's why it's nice to report that a number of pollination scientists have actually tested this. No one study covers the entire range of horticultural conditions but we can piece together a pretty good set of answers by looking at half a dozen papers published this decade.

I started off down this winding garden path by reading a recent article from the University of Pennsylvania titled "More Than Meets the Eye? The Role of Annual Ornamental Flowers in Supporting Pollinators". This is an open source paper (yay, authors!) from the lab of Christina Grozinger, a well respected pollinator biologist.

Emily Erickson
I was interested in this article because it looked at annuals, which are much more likely to be found in say a window box or balcony planter than perennials. Emily Erickson, a Ph.D. student in Christina's lab, went deep rather than wide. That is, instead of looking at 25 different species of ornamental annuals, she looked at just 5 species (Alyssum, Egyptian Starcluster, Lantana, Marigold, and Zinnia) but she evaluated 5 different strains of each species. This is really important because plant breeders don't usually select for things important to pollinators: nectar and pollen. Instead breeders look for color, size, and length of bloom. Some ornamental strains of common annuals are literally castrated - they provide no pollen to avoid mussing up your flower arrangements. Not so good for many pollinators!

By looking at many popular strains of some of the most often recommended annuals for pollinators, Emily was able to say not only which species of annual attracted the most butterflies, bees, and birds but also whether it matters which strain you find at the garden center. The short answer is yes, it very much matters.

Here are the 25 ornamental annuals Emily Erickson tested for attractiveness to pollinators:
Erickson et al 2019, Figure 2. Environmental Entomology. Copyright © 2019, Oxford University Press

Could you pick the best BBB plant by eye? The results are surprising. The most attractive strain, by number of pollinator visitors, was Alyssum 'Snow Princess', and in second place Alyssum 'Frosty Knight'. Snow Princess had more than three times as many visitors as the average strain tested.

Why? Well, one factor is that those two Alyssum strains have been bred to be sterile - they don't set seed. This means sterile flowers keep on providing nectar and pollen much longer than a flower which has been pollinated and turns its energies to setting seed. Florists and garden show exhibitors know this trick - a mesh bag or old stocking tied over a spike of delphiniums or larkspurs will give many more flowers in bloom for the vase than a flower spike in which pollinators have had access.

The other three Alyssum strains are all fertile and had average numbers of visitors, except for 'Wonderland Deep Purple', which had the third lowest visitor count of the 25 strains. Strain matters!

"Egyptian Starcluster" is a more awkward name than Pentas, the scientific genus name. This species is hyped as great for pollinators, but had the lowest average visitation over the 5 strains, as well as the lowest and second lowest strains. I'd avoid it! Here are quotes from three different websites:
"Pentas is one of the best pollinator friendly plants you can grow."
"Colorful pentas, also known as Egyptian starcluster or star flower, are one of the best choices to attract pollinators like butterflies and hummingbirds to your garden."
"Vibrant blooms are a magnet for pollinators."
Zinnia 'Peppermint'. Clement Kent, CC-by-SA 3.0
 Emily Erickson noted not just the number of pollinators but the kinds as well. Alyssum had mostly bees and flies visiting, while marigolds had bees and some butterflies. Lantana had almost entirely butterfly visitors, while Zinnia had a good balance of types of pollinators. Please note that among Zinnia strains, you're best off with those that are not too doubled. In the picture from my back porch this summer on the left,  are three blooms from the seed strain 'Peppermint'. The one on the right is so doubled that the actual florets (the little yellow bits in the center) are covered up. That flower may be nice to our eyes but it will get no pollinators. The one in the middle is what you are aiming for.

Monarch on Zinnia. Clement Kent, CC-by-SA 3.0
If you buy zinnias at a store, look for a broad central region with actual florets, such as the one on the right from my garden. These really do get a great stream of butterflies, bees, and hummingbirds.

Well, it's time for me to help with dinner. Next time I blog, I'll look at scientific studies of pollinators on perennials and herbs, with some delicious advice for balcony gardeners.


Saturday, October 26, 2019

More succulents we will have on Monday, October 28th 2019

At Barry Parker's talk we'll have divisions of other succulents. Two that I'm including are the Queen of the Night cactus, which has grown reliably in a pot for me for thirty years, and was probably as old when I got it from another indoor gardener. I'm just bringing one cutting, but in the spring I can provide many more. I'm bringing the pot inside this weekend for the winter. It has extraordinary, gigantic blooms! For more details, click on the above link.

Another plant I'm contributing is from southwestern Morocco and the Canary Islands. It's variously called either Caralluma (the older name) or Apteranthes burchardii. There's a nice snippet about it here. Like the Stapelia or Carrion Flower that I am also contributing, this is one of what I call the stinking milkweeds. That is, it's a succulent in the milkweed family with fleshy stems, no leaves, and grows in very dry areas. Unlike the giant carrion flower, this has clusters of many minature flowers at the tips of the stem in early summer.
Caralluma europaea - Wikimedia

Caralluma fimbriata
If you ever want to amuse yourself by specializing in one kind of houseplant, the Carallumas are an option. A quick waltz through some of the species:
Caralluma acutangula - from Wikimedia

Thursday, October 24, 2019

Stinking milkweeds - excellent succulent houseplants!

Celebrating our upcoming talk on succulents by Barry Parker, here is one of the more unusual succulents in the milkweed family. Stapelia is an African genus of leafless succulents from near-desert regions. The swollen stems look a bit like cacti, although there is no relationship.
Stapelia grandiflora stem and bud. Clement Kent, CC-by-SA 4.0

These beauties spend the winter in my kitchen window, as they won't tolerate temperatures below about 10C/50F. Most importantly, in winter they need to be kept almost bone dry. I water them perhaps once a month between November and May, and only very sparingly.

view of bud from above. Clement Kent, CC by SA 4.0
All of this changes when they go outside after it's warm enough. I give them a week in partial shade to prevent sun scorch, then move them to the sunniest part of my porch. Then I begin a regular program of watering with occasional infusions of soluble fertilizer. By July or August I'm greeted by the huge buds, about 3" wide by 4" long.

Several days will pass as the buds grow, and grow, and grow. Finally, one morning before I'm up, they will open.

When this happens, there's a treat for many senses. The nearly foot-wide blooms are a rich golden-orange with dark purplish-red stripes. The hue deepens to the same red meat color at the center of the flower, where elaborate floral parts sit.

freshly opened Stapelia flower, 10" wide. Clement Kent, CC by SA 4.0

The flower is densely covered in long hairs or cilia. Brush them with your fingers - some say it feels like fur.
Stapelia grandiflora closeup showing hairs. Clement Kent, CC-by-SA 4.0
 So far we have sight and touch covered. Take the next step: get close to the flower and take a whiff.

Phew!!! smells like rotting meat!  You've just discovered the most powerful lure in this flower's pollination bouquet. It looks and smells like a rotting carcass, to attract its pollinator: carrion flies.

Let's look again at the center of the flower. See the white egg clusters? They are from the greenbottle fly, one of the first flesh-feeder to arrive at dead animals in the wild.
greenbottle fly eggs on Stapelia - Clement Kent, CC-by-SA 4.0

Click on the video below to see the hatched eggs - a.k.a maggots - waving in the breeze as they try to find the yummy dead meat. Mama greenbottle makes a flying visit.

If you sit and watch your flower for a bit longer, you'll see other visitors.

If you should be lucky enough to have two flowers open at the same time, and the flies carry the pollinia (specialized pollen clusters) from one to another, then you'll eventually see a very milkweed-like seed pod develop, and open to reveal seeds with fluffy appendages to help them fly.

If you want to share with friends, or just have more for yourself, use a clean knife to cut one of the stems (or just snap it in half). Don't get the white sap on your skin - it is irritating. Let the detached stem sit in an airy, dry, sunny place for several days to heal. Then plant it in very free draining material, like you would use for a cactus (gravel is good). Don't water more than once every few weeks until you see signs of new growth. 

Sunday, October 20, 2019

Balcony and Apartment Gardens with Succulents

Barry Parker taught Animation at Sheridan College, and his students work at Nelvana, Pixar, Disney, etc. Barry also helped design animation programs in India and Singapore and has been an international judge at film festivals. 

Barry Parker tufa trough with alpine scene
one of Barry's troughs
But I know Barry best as a fantastic gardener. The garden he and Michel LeFebvre created in Toronto was a wonderful place to learn about new plants and new techniques, all arranged and executed with a very acute sense of design. He ran courses on how to make your own tufa containers for succulents on your porch or balcony.                                                                                                                                                                        But, (alas!) on retirement Barry left us for a lovely second floor apartment with two balconies in Montréal. He now gardens mostly in pots, growing a wide range of succulents and other plants, often from seed. When I visited him in September he had some very nice aloes he grew from seed with fascinating new colour patterns on the leaves - and they were blooming too!                                                                                                                                                               
seed-grown agave by Barry Parker
one of Barry's seed-grown aloes
So, I'm very happy that Barry will be speaking to us on Monday October 28 (details above). All year long, members of the Horticultural Societies of Parkdale and Toronto have been making divisions of succulents to bring to this meeting. A little bird even told me that one of Barry's larger agaves will be at the meeting to be given away. I myself have divisions of my night-blooming cactus and of my Madagascar Milkweeds (Stapelia) and their Canary Islands relatives Caralluma to give away.                                                                                                   We really hope to see some apartment/condo gardeners at our meeting. Attending the meeting is free as always, but for this special event we are giving new members first choice of the succulents and indoor gardening books (1 per new member, please!).

Thursday, October 3, 2019

Back to the Future - Retiring to Help Pollinators

In the last few years, my posts to this blog have been sparse because I've been very, very busy delivering many academic commitments. But as of 3 days ago, I retired from full-time scientific work to focus more on conservation - hurray!

Pete Ewins - in his garden. photo-CK
This fall I'm rejoining the board of the Horticultural Societies of Parkdale and Toronto, who supported several large pollinator projects I'll be blogging about in the coming months. I'm also collaborating with In the Zone Gardens, a joint project of WWF Canada and Carolinian Canada. ITZG is helping people plant pollinator and wildlife gardens. Today I'll be joining Pete Ewins of WWF Canada at my favorite organic farmers' market, Dufferin Grove, where I've done previous pollinator events.

At Dufferin Grove I'll be contributing several pollinator perennials and shrubs to Pete's free giveaway table. I'm highlighting some of them below.

Monarch on Swamp Milkweed - photo CK
One plant I may have trouble giving away is Swamp Milkweed, Asclepias incarnata. It's a great plant, but my seedlings are small plugs, which most people ignore. But experienced gardeners know that a plug plant put in the ground this fall will be a big, blooming fountain of flowers next summer. So I hope to give many of my 50 seedlings away today. I grew them from wild-collected seeds from three locations in Ontario and Québec, courtesy of the North American Native Plant Society Seed Exchange. This way gardeners will get wild plant vigor and a range of flower colors from pale pink to red.
Arrowwood Viburnum - F.A. Martin, CC By SA 4.0

I'll also have three good sized bushes - two Viburnums and one Ninebark.

Arrowwood Viburnum, Viburnum dentatum, is a big bush in the wild but smaller varieties have been selected for gardens, which is what I'm giving away. Like our other native viburnums, it has attractive
clusters of white flowers in spring for the pollinators, followed by blue berries in late summer and fall for the birds. Its leaves turn lovely shades of red in autumn. The leaves also feed a variety of caterpillars, including those of the Holly Blue butterfly and the Hummingbird Clearwing Moth.

Holly Blue butterfly - Charles J Sharp, CC BY SA 3.0

Hummingbird Clearwing Moth, Judy Gallagher, CC BY 2.0

Ninebark (Physocarpus opulifolius), is a shrub much used by landscapers for its good foliage and growth form. As I pointed out in my article "Soil Spectrum", in Ground, the journal of Landscape Ontario, Ninebark is one of the native plants which gets it roots extremely deep in the soil, so after the first year it never needs watering and in fact brings up nutrients from subsoil layers to the topsoil. With abundant white flowers in spring and various native moth caterpillars living on the leaves (to feed the baby birds!), its a perfect backdrop to a pollinator garden.
Ninebark, by Eric Hunt, CC BY-SA 4.0

Thursday, August 30, 2018

Night Blooming Cactuses - Queens of the subtropical pollinator garden

Night blooming cactus

Not everyone lives in the colder north. Pollinator gardens are possible and needed in tropical and subtropical climes, due to the continued loss of habitat there. One of the most fascinating groups of plants and their pollinators is the night blooming cactuses of subtropical and tropical America.

This is a surprisingly large group, with many species (Wikipedia).  The one I grow is probably Epiphyllum oxypetalum which is a native of southern Mexico to South America. This is one of many cacti pollinated by bats and some sphinx moths. The amazing videographer Louie Schwarzberg shows this in his The Beauty of Pollination clip. Look for the mama bat carrying her child! And, near the end of the portion on bats, there's a bat coming by some months later and eating the delicious fruit of the cactus.

That's right, many of these cacti have large, good tasting fruit. One of the best known (find it in most Chinese or Vietnamese groceries) is the dragonfruit.

My night blooming cactus tempts me for many days before the event with the gradual growth of the bud, starting from a tiny pip on the edge of a leaf to a 3-6 inch bizarre object which finally begins to show white on the petals. Then I know that it will open the coming sunset. I try to invite friends and neighbors over for that evening to sip a glass and watch the process.

About half an hour after sunset the petals will begin to open, in a process that may take an hour or more. When the outer petals are forming alien-looking spikes at right angles to the main flower, it's fully open and then the fragrance begins to build.

At this point guests are often on hands and knees, looking into the amazing corolla and sniffing it:

You can see a nice time-lapse video of a potted plant blooming at YouTube

If you want to grow Epiphyllum oxypetalum as a house plant it's not hard. Give it a freely draining soil and bring it indoors well before frost. During winter, give it hardly any water and no fertilizer. Around March-April, long thin stems will begin to grow upwards, possibly reaching 10 feet in a really vigorous plant. You can pinch these to keep them in bounds. Short air roots grow from these stems, which the cactus uses in nature to anchor itself to the bark of tree trunks or to rocky slopes.

Once it is reliably mild outside, you should move your cactus outdoors. But, for the first week or two, make sure to keep it totally shaded - otherwise the leaves will burn. I cover my plant with a muslin-like cloth at first. In Toronto's latitude, after this hardening off the cactus can take full sun.

As soon as it is ready for sun, you can start giving your plant plenty of water with a low-nitrogen fertilizer, diluted to half strength. Once it gets hot, the skinny stems will begin to widen into flat green "leaves".  After leaves have matured for a month or two, you'll find small swellings on their edges that grow into flower buds.

the Wellesley College cactus night

Selby Gardens Cactus Evening
Around the world, those lucky enough to have night blooming cactus ready to pop have thrown parties that may go dawn to dusk.

In the New York Times, JoAnna Klein describes the cactus and some of the parties celebrating its bloom. She quotes from a 1937 newspaper clipping describing a cactus party at Blithewold Estate:

 “Bristol’s Cereus Puts on Show” shouts the headline. An eye-popping photograph shows the trailing leaders of  a huge plant with about 29 flowers in bloom. The caption explains they are only a portion of the 200 or so that opened on a night-blooming Cereus in a greenhouse on the estate of a certain William L. McKee. This from the Providence Sunday Journal, August 8, 1937.
The article notes an “enthralled audience” gathered to enjoy the spectacle. It is reported that at about 8 p.m. the “gorgeous white blossoms began to expand from their green pods.” This corresponds to the time when our Blanca begins to move, give or take 20 to 30 minutes. A certain W.H. Owen, superintendent of the property had been caring for the plant over the previous 12 years and had become thoroughly acquainted with its habits. “He said he expected it to blossom several nights ago but it didn’t probably because it was bearing more blooms than ever before.”
By 8:30 p.m., it is reported, “fully 150 blooms, six inches in diameter and containing a circle of creamy yellow stamens within were exposed to view.”
“The flower bears some resemblance to a huge white tulip and exudes a powerful, sweet fragrance, completely permeating the atmosphere of the hothouse.”  This particular specimen, Mr. Owen explained, had been developed from a cutting brought from Peru 30 years previous.   The plant had spread the entire breadth of the building, some 14 feet.
Eudora Welty

Eudora Welty was a celebrated Mississippi writer, who had a beautiful garden. In her book The Golden Apples she wrote that when her night-blooming cereus plant (“a naked, luminous, complicated flower,”) began hinting at exposing its fragile white buds each year, Welty would throw parties that would last from dusk until dawn in its honor.

If you are interested by this, you could try growing one or two (or 5 or 10, space permitting) of the gorgeous hybrid "Cereus" cacti, many of which can be grown in hanging pots. They have a range of flowers from crimsons to pale golds. I'll finish this off with a photo by "Lance", from his Hawaiian blog: