Thursday, February 27, 2020

Project Swallowtail Plant List - Key plants for Swallowtail Butterflies

This is the first of several pages that will list native plants we are using to support native pollinators in Project Swallowtail. This page highlights species we're using to support native Swallowtail butterflies. Other pages will give more complete list of trees, shrubs, perennials, and grasses beneficial to different birds, bees, butterflies and other pollinators.

But first, let me direct you to a previous post on just this subject: Hops and Spice, Pipes and Paws - How Large a Tale will you Swallow? That post has fun with some of the history around these plants, animals, and human customs.

Our plant list for swallowtails:

  • Hoptree
  • Pipevine
  • Pawpaw
  • Spicebush
  • Sweet crabapple
  • Tuliptree
  • Black cherry
  • Pussy willow
  • Aniseroot
  • Golden Alexanders
  • Great Angelica
  • Anise, caraway, coriander, dill, fennel, lovage, and parsley

Details - see below!


Giant Swallowtail
Giant Swallowtail, Gordon Roberton CCbySA3.0

There are only two Ontario native plants Giant Swallowtail caterpillars will eat, and one of them, Prickly Ash, is a monster in the garden. Don't go there, unless you have a big property, and you want to be able to say, as Sean James does, "kiss my Prickly Ash" to annoying visitors.

Instead, we're planting Hoptree (Ptelea trifoliata). This shrub to short tree (up to 6m tall but can be pruned much shorter; 2-3 m along the shores of Lake Erie) thrives in the sandy soils found in our area, and is not too particular about light or moisture. 

Ptelea trifoliata 'Aurea' ; photo Karl Gercen
We'll be using plants grown from local seed, but if you are into foliage colors you can consider the variety "Aurea" which won a RHS Award of Garden Merit for its pale spring leaves.

I wrote about hoptrees and giants in this post which you can peek at for more details, including how to grow your own from seed.

Be sure to look online for images of Giant Swallowtail caterpillars so you can recognize them when a female has found your bush! 


Pipevine swallowtail, ©Troy Bartlett

Pipevine Swallowtail

Here's another butterfly with only a single native host, the pipevine Aristolochia macrophylla. This Appalachian species is at the northern limit of its natural range with us, although it was in much demand a century ago as a way of shading porches. The pipevines are a large family in the tropics, and they all share compounds in their leaves which are very bitter if eaten. Like the monarch does with milkweed, Pipevine swallowtail caterpillars store up these bitter compounds so that the adults are very nasty tasting for birds.

Pipevine can be a vigorous grower where it is happy. A fence is an ideal spot for it, like the big spread of it on Ward's Island near the Island Cafe, which used to harbour many of these butterflies. Most soils are OK, but the vine doesn't like to be too dry. I've seen it growing well in half shade.


Zebra Swallowtail

The only local host for the elegant Zebra swallowtail is the pawpaw tree, whose very tasty fruit is a fine
reward for pollinator gardeners in the fall.

It takes two different pawpaws to cross-pollinate and set fruit, and being a small tree they may take five years after planting to reach blooming size. But after just a few years zebra swallowtails can lay eggs on the leaves - they don't care about the fruit.

In nature, pawpaws are often found in moist soil near streams or rivers, and can tolerate partial shade. Once they reach blooming size, they send up new stalks from suckers. I trim mine off once a year, a 10 minute task.

My two pawpaws were grown from pawpaw fruit from the Niagara area, sold by a farmer in the Dufferin Grove Organic Market. I know of at least two other properties in our area with large, well-yielding pawpaws.

Spicebush Swallowtail

Spicebush swallowtail
Compare the blue hind wings of the Spicebush and Pipevine swallowtails. They are part of what biologists call a mimicry complex. Lindera benzoin - Spicebush - is the favored host plant for Spicebush caterpillars, and also for the Promethea moth. The Tiger Swallowtail and the Imperial moth also feed on the leaves.

Spicebush has small but fragrant yellowish flowers in spring and red fruit in fall, although there are separate male and female plants, so you need one of each within a few back yards of each other to get fruit. Fruit, leaves, and stems are aromatic and have been used in teas and other recipes.

Spicebush blooms more in the sun but tolerates shade very well. My bush is planted north of an old pear tree where it gets several hours of afternoon sun.

These swallowtail caterpillars can also feed on Tuliptree leaves - see the Tiger Swallowtail, below.

Male spicebush flowers - public domain
Imperial Moth, Joel Mills, CCbySA 3.0

Tiger Swallowtail
Eastern Tiger Swallowtail, Derek Ramsey CC by SA 3.0

As a child I didn't know that "Tigers" could be one of several very closely related species. The USA tiger's caterpillars feed on Tulip Trees and a fair number of other trees, the Canadian tiger replaces tuliptrees with poplars, and there is a hybrid species left over from the ice ages in the Appalachian mountains. 

To add more to the confusion, the females can either be traditionally tiger-colored or have a black form which looks a great deal like the Black Swallowtail (below).

There are about 7 or 8 host plants for the Tigers, but the ones we are featuring in Project Swallowtail have benefits for other pollinators too. These are the Tulip Tree, Black Cherry, Sweet crabapple, Pussy Willow, and our friend the Hoptree (above).

crabapple, Per Palmkvist Knudsen,
CCbySA2.5

Sweet crabapple

Malus coronaria is native to our region and an excellent small garden tree, for pollinators in spring, caterpillars in summer, and birds in fall. Full sun produces the greatest bloom and fruit set. Jam is delicious!





Tulip tree, Clement Kent CC by SA 3.0

Tulip Tree

Liriodendron tulipifera is a native giant magnolia - up to 50m/160ft in the south. An excellent shade tree, we planted it in Kathy's Garden to give shade and beauty to seven future generations, as the ash and beech and Austrian pine trees around it die over the next few years. It's valued for its wood.

Honeybees love tuliptrees in bloom, and make a flavour-rich dark honey from it. A friend gave me a jar of it from a grove in Ohio, which I save for special occasions.

Tuliptree Silkmoth, Thomas Barnes Public Domain
Tuliptrees are native to Carolinian Canada, but used to be rare in Toronto. A friend now grows them as far north as Creemore. The City of Toronto has added them to the list of trees the city will plant for free in your front yard if you ask. Several in the Dufferin Grove neighbourhood have now reached 3 stories tall - this tree can grow several feet per year when young!

 It hosts "only" 28 species of native moths, including the giant Tuliptree Silkmoth, and of course the tiger swallowtail.

Black Cherry

Prunus serotina is like sweet crabapple - flowers in spring, leaves in summer, and fruit in fall for birds. It's like tuliptree as it is a large tree with valuable lumber which can live hundreds of years. 

I had a property on the shore of Lake Huron with one enormous Black Cherry and several of its children. The big tree had been struck lightning but survived. Just down the hill to the lake grew Alternate-leaved Dogwood, whose blue or purple berries ripened just after the cherries. We had torrents of birds for those weeks!







Emperor moth. Jena-Phillippe Harmon, CCbySA 3.0
Talk about beauty: Coral Hairstreak, Eastern Tiger Swallowtail, Red-Spotted Purple, Spring Azure and Viceroy butterfly and Io, Cecropia, Promethea, and Emperor moth caterpillars feed on the leaves - it's one of the top trees in ecologist Douglas Tallamy's list of best trees for wildlife.











Pussy Willow

Pussy willow - Silk666, CCbySA 3.0
The native willow Salix discolor is a champion at supporting pollinators, and children! A few stems of "pussies" is one of the finest signs of spring. Keep them in water for a few weeks and you'll find roots on the lower stems. Plant them out in a sunny, moist spot and in just a few years you'll have pussies of your own to give away.

I watch my cut stems carefully. Pussy willows have male and female plants. If the soft white of the buds is replaced by golden pollen-bearing stamens, you have a branch from a male tree. The early spring pollen is incredibly valuable to early spring bees, including honeybees and bumblebees.

And the butterflies and moths! Another Tallamy favorite, pussy willow supports Acadian hairstreak, black-waved flannel moth, cecropia moth, Compton's tortoiseshell, cynthia moth, dreamy duskywing, eastern tiger swallowtail, elm sphinx, imperial moth, Io moth, modest sphinx, mourning cloak, polyphemus moth, promethea moth, red-spotted purple, small-eyed sphinx, twin-spotted sphinx, and viceroy. In fact, a small grove of willows is one of the best ways to guarantee seeing mourning cloak butterflies on mild days in late fall and early spring. 

OK, enough about Tigers and their hosts. One more swallowtail to go:


female black swallowtail, Kenneth Dwain Harrison CC by SA 3.0

Black Swallowtail

The black swallowtail Papilio polyxenes is probably our most common swallowtail. Males and females are both black but differ in the amount of blue (mimicking the pipevine swallowtail).




male black swallowtail, D. Gordon Robertson CC by SA 3.0
Males defend mating territories fiercely, and if you visit a hilltop in High Park in summer you may see an aerial battle between two males. 

Females search for plants from the carrot/Queen Anne's lace family to lay their eggs. Given the abundance of the invasive but well established Queen Anne's Lace (wild carrot), they don't have to look far.

If you want some native plants to feed black swallowtail caterpillars and provide blooms for other pollinators, I recommend three. 

The dappled-shade adapted Aniseroot sweet cicely (Osmorhiza longistylis) has anise-scented and flavoured leaves and springtime white flowers. 

Golden Alexanders
Derek Ramsey CCbySA 3.0

Golden Alexanders (Zizia aurea) has beautiful yellow clusters in May or June; it dies back if the soil gets dry. In addition to the black swallowtails, the solitary mining bee Andrena ziziae feeds its young only the pollen of Golden Alexanders. I have it in a spot with half a day's sun.




Great Angelica (Angelica atropurpurea) is a native perennial we should know better. Its sweet stems and roots were used for making candy, and Indigenous peoples have a number of medicinal uses for it. With golden blooms on purple stems three to six feet tall, it is a major plant in the water or rain garden. It needs moist soil and a reasonable amount of sun. Hordes of smaller pollinators will be attracted to the blooms.

Black Swallowtail caterpillar
@401rooftopgarden  - CC by SA 3.0
And then, there are all the non-native but delicious herbs that will feed black swallowtail caterpillars. Anise, caraway, coriander, dill, fennel, lovage, and parsley are some of the more common ones. On the rooftop garden of 401 Richmond in downtown Toronto, gardener Saskia Vegter found caterpillars last year, showing that apartment dwellers can attract this butterfly.














Thursday, February 6, 2020

Balcony Herbs for You and for the Pollinators

Many of us live in apartments, without a plot of earth for a garden. If you want to treat yourself and pollinators well, what should you grow in pots or planters?

My answer is Herbs. They'll be great for you in the pot, pan, or salad, and if you manage them right, full of flowers for pollinators. Further, many herbs are very tolerant of the wind and drying conditions of an upper-floor balcony, so they'll be easier for you to grow than other flowering plants.

Basil flowers - by Natalie Ward
Basil is one of my favorites. Even though I have a back yard, it's too shady these days for basil to get the full heat and sun it needs. So, I grow it in pots on the deck.

Carpenter Bee on Basil - Gideon Pisanty,
 CC by SA 3.0
Many people trim off the basil flower spikes, because it prolongs the growth of the leaves. But the flowers are excellent in salad, and very
attractive to pollinators.

If you have a big pot, I'd recommend a mix of sweet basil, lemon basil, Thai basil, and holy basil. Put it next to your patio tomatoes to remind you to use the leaves with tomato dishes!

Thyme in a pot - Greenmars, CCbySA 3.0

I never have enough Thyme!  It's highly tolerant of drying and heat. Many varieties are winter hardy. You can find half a dozen different flavors and forms, with flowers ranging from pink to pale purple to white. As with basil, if you have a long window box, try mixing several varieties together. The flowers are edible but strong tasting, so best in soups and stews.

I hope I don't need to remind you not to use pesticides on your herbs???


Coriander/Cilantro - H. Zell, CC by SA 3.0
 A fantastic group of herbs to grow from seed in pots are the carrot family herbs dill, fennel, and coriander (Coriandrum sativum). They grow easily from early spring sown seed, but they need a but more watering than thyme does. Flowers, of course, are their way of making the yummy seeds, so do double duty on your balcony. However, these annual plants die back after the seeds ripen, so plant several waves of them spaced about two weeks apart for whole season enjoyment.

Dill in full bloom - Clement Kent, CC by SA 3.0
If you use the leaves (coriander leaves = cilantro), you can pinch one of these plants several times to get it to grow more bushy. Then when you stop pinching, you'll get an explosion of flowers.




 In summer heat, the leaves can be all too fleeting. Of course, you can dry them, but my in-laws used to freeze dill  (Anethum graveolens) just after picking, to have fresh green sprigs on potatoes or fish - an Estonian favorite!


Fennel -  K√∂hler's Medicinal Plants (1887)





"Above the lower plants it towers,
The Fennel with its yellow flowers;
And in an earlier age than ours
Was gifted with the wondrous powers
Lost vision to restore." - Longfellow, The Goblet of Life, 1842

Fennel (Foeniculum vulgare) is biennial, so it doesn't bloom until the second year. In the ground it is quite hardy but in you may need to wrap the pots to bring it through our winters. Remember, Longfellow warned you it will grow tall! Bronze Fennel is an attractive variety.




A bed of Chives in June - Clement Kent, CC by SA 3.0

Bumblebees like Chives

Garlic Chives - Clement Kent, CC by SA 3.0
Chives (Allium schoenoprasum) make a good pot plant, although I find if not watered enough they get rather bitter. For the purple species, blooming is in early summer. Remove the flowers when they fade for a smaller bloom later in the summer.









Chive flowers are longish, favoring bumblebees.

At my friend Jon's cabin near northern Georgian Bay, chives have naturalized on the granite rocks where they grow in a very, very thin layer of gravel. They also grew on nearly bare granite at my parents' cabin near Thunder Bay. So I can say with complete confidence that they will be hardy in your pot on the balcony.


"He who bears chives on his breathe,
Is safe from being kissed to death."
Marcus Valerius Martialis, 80 A.D.

Martial's epigram is even more true for Garlic Chives (Allium tuberosum), whose leaves have the added flavor and scent of garlic. I used to grow these under the kitchen window for a milder addition to salads than a crushed garlic cloves, but they seeded so abundantly I had to exile them to the back of the yard. Flowers arrive in late summer, and are attractive to pollinators, but too strong-tasting to me to use in the kitchen.



Spanish Tarragon - George Hull, CC by SA 2.5
Did you know that there are many species of marigolds in Mexico? Tagetes lucida is also known as
Spanish Tarragon. It's completely unrelated to French Tarragon, which tends not to thrive on balconies. But the Spanish Tarragon marigold is happy in sun and baking heat. The leaves are good in many of the same recipes where you'd use a regular tarragon. And, in late summer/early fall, you get many small yellow flowers for the bees.




Wow - so many more herbs to go! For sunny planters I'd also recommend marjoram and oregano, both great bloomers and worthy in the pot or on the pizza. But let's turn to those of us whose site faces north, or an adjoining building.



Make mine Mint! There are many species of mint (Mentha) and most of them will tolerate some shade. They are better in pots than in the soil, because they tend to runner about and take over the garden if you let them. They are of course an essential of herbal and Mediterranean teas, and of many kinds of cooking recipes. There is spearmint, peppermint, lemon mint, chocolate mint...the list goes on.

I've put multiple mints in one pot, and this works fine for the first year. But by the second and later years one has driven the others extinct.

Flowering happens frequently, and I like to add the flower spikes to fresh mint-water for summer hot days. But, please pick them off when they are done, or your plants will tend to get woody and leggy.

There are many other herbs, of course - every culture around the world has its favorites. Try some that bloom well on your balcony, and share your herbs with the pollinators!