Category Archives: Shade Gardening

Advice, Bees & Pollinators, Botanical Names, Butterflies and Moths, Invasive, Native Plants, New Gardens, Planting, Shade Gardening, Sun Gardening, Wildflowers, Winter Sowing

Beware those Wildflower Mixes!

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    By Emma Murphy, Master Gardener

    The Oxford Dictionary defines “wildflower” as “a flower of an uncultivated variety or a flower growing freely without human intervention.”  It has nothing to do with the species’ native range, its benefits for pollinators, or its impacts on ecosystems. A “wildflower” could be native, non-native or at worst invasive.

    Last year at this time, I wrote a blog post about roadside wildflowers. Most of these flowers (like chicory [Cichorium intybus] on the left or Oxeye Daisy [Leucanthemum vulgare]) are non-native opportunists from Europe or Asia that colonize quickly on disturbed sites or ditches and wetlands and outcompete native species, but lots of people assume they are native because they’re everywhere along roadsides (I did for years!).

    The bottom line? Wildflower does not equal native.

    So, if you want to buy a wildflower mix to create a long-term habitat for native pollinators, beneficial insects, and bees in your gardens, the mixes found at big box stores and large nurseries are probably not the mixes you want.

    Why the Label can Mislead

    A lot of retail “wildflower” mixes are designed for fast colour. They focus on non-native annual flowers, which bloom quickly and beautifully in the first season but fail to support local pollinators (and isn’t that the point?), or can even become invasive.

    While mixes don’t need to be exclusively comprised of species native to Ontario to provide good habitat for pollinators and beneficial insects (although that’s the best case scenario), they shouldn’t be invasive and should be perennials so that your garden continues to look good year after year.

    Why is this Important?

    Pollinators need more than flowers that simply look pretty. They need plants that fit local conditions and provide food, shelter, and nesting support over time – that are beneficial to the local ecosystem.

    What’s the biggest red flag? Seed mixes that only provide the common names of species instead of the scientific (Latin) names. While common names can be easier to remember and pronounce, they also vary by region, and one plant can have several different common names. This can cause confusion about what the actual species is.

    A Case in Point

    Last year at the PMG A Day for Gardeners a lady approached me with a large bag of pollinator seed mix as I was working on the advice table. She wanted to know if it was good. There were no Latin names (first red flag) so I asked her to leave it with me to investigate.

    After checking as best I could we determined that almost 80 percent of the seeds were not native and were annuals. She planned on returning the bag to the store.

    The Problem with Mixed Seed Packets

    • Big companies that sell across Canada create one seed mix to sell across the entire country but what might be native in Alberta probably won’t be in Ontario
    • Seeds have different germination requirements so you may find some seeds don’t germinate at all
    • Different seeds may not grow well together
    • Some seeds may not like your site conditions and others may become dominant

    The worst problem is if they contain non-native, invasive seeds.

    Let’s look at an example. McKenzie Wildflowers Pollinator Mix.

    1. Only five flowers native to Ontario (*) and all less than 5% of the mix except for the Purple Coneflower, which is 12.67% and Lanceleaf coreopsis, which is 6.33%
    2. The first three flowers, which comprise over 42% of the mix, are all non-native
    3. Your seeds are only 14% of the mix – the rest is vermiculite (filler)

    Here’s a full breakdown.

    Better Ways to Choose

    The best seed mixes are transparent. They tell you exactly which species are included, how much of each is in the packet, and whether the plants are native to your region. Regional native mixes can be useful, especially when they include a balance of annuals and perennials and are clearly suited to your regional climate.

    If you’re serious about supporting biodiversity, the most important thing you can do is choose seeds that are native to your specific region.

    I’ve seen several companies create better wildflower mixes in the past few years, including Northern Wildflowers, Native Plants in Claremont, OSC and, for large projects, St Williams Ecology Centre. I’m sure there are others I have missed so be sure to comment if you know any!

    One key thing to remember with native plant seeds is that most need winter stratification (a cool, wet natural dormancy period over winter) to germinate well. That means that direct garden sowing should take place in the late fall after the first frost (mid-September to November, depending on your region), not in the spring. If seeds can’t be stratified, many will not germinate until the following spring and germination rates may be slightly lower.

    A Simple Rule for Gardeners

    If your goal is to truly help pollinators, choose local native plants first and sow your seeds in the fall for best germination. Avoid mystery mixes (especially those with only common names), check the label closely, and be cautious of bags that promise an instant meadow without giving details. Colourful flowers are nice, but real pollinator support comes from the right plants in the right place, and that doesn’t happen overnight.

    Choose the Right Seeds – Go Native, Not Just “Wild”


    Additional Reading

    Bees & Pollinators, Native Plants, Perennials, Shade Gardening, Sun Gardening

    What’s Still Feeding Pollinators in Your Fall Garden?

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    by Silvia Strobl, Master Gardener

    It has been a warm start to the fall season, but despite a little more frequent rain in September, the summer drought has continued here north of Peterborough in my 4b Plant Hardiness Zone garden. My soil is also sandy and dry. So what could still be blooming and feeding our most effective pollinators, the native bumble bees?

    Although bumble bees are more active in spring and summer, they still need nectar and pollen in fall because the gynes, unmated females that will become next year’s new queen bees if fertilized, are mating and then must build up fat reserves and find a place to overwinter (The Xerces Society 2025). At this time of year you may see bumble bees sleeping on flowers in the morning, especially after a cold night or overnight rainfall. These are mostly the solitary male bumble bees that sleep outdoors. They are searching for a mate, and then they will die. Bad weather may also force female bumble bees to sleep outdoors, but their preference is to return to the hive at night (St. John 2023).

    Here are a few drought-hardy native species that were still blooming and supporting pollinators in my garden on October 10th. All are resistant to deer. Sun, soil and moisture requirements, height, bloom colour and bloom time are noted for each.

    Smooth Aster (Symphyotrichum laeve)

    Full sun – light shade; Sand, loam, clay; Dry to Medium; 4 feet tall; Lavender to light blue; September – October

    Smooth Aster has very frost-hardy flowers that often bloom into early November. The lavender to light blue flowers provide a lavish display. It has an upright form, is salt tolerant, and has the ability to survive drought.

    Given that it blooms into early November, Smooth Aster is an important food source for late season bumble bees. The backdrop of Sugar Maple in full fall colour contrasts nicely with its lavender blooms.

    New England Aster (Symphyotrichum novae-angliae)

    Full sun – Part sun; Sand, loam, clay; Moist-average soil; Tolerates dry soil but may look scraggly; 2-5 feet tall; Purple, pink; August – October

    New England Aster is another late bloomer, often lasting until it is hit by a few hard frosts (Booth nd). It is a clumping perennial that can be divided every 3-5 years and also “politely” seeds into garden gaps. To keep it from flopping over in fertile soils, it can be “Chelsea-chopped” in mid-June to restrict its height. It is an important nectar plant for migrating Monarch butterflies, as well as a larval host for 5 butterflies and more than 40 moth species (Booth and Gray 2024).

    A male Common Eastern Bumble Bee (Bombus impatiens) sleeping on New England Aster blooms.

    Zig Zag Goldenrod (Solidago flexicaulis)

    Part shade to Full Shade; Prefers, fertile loam but tolerates heavy clay; Well-drained soils; 1-3 feet tall; Yellow; August – October

    Zig Zag Goldenrod is a non-aggressive goldenrod that is a great addition to the shade garden. It provides pollen and nectar for both short- and long-tongued bees, wasps, flies and butterflies and it is the larval host plant for over 45 species of moths (Booth and Gray 2024).

    The leaves of Zig Zag Goldenrod can also change colour in fall, adding to the plant’s aesthetic value.

    Blue-stemmed Goldenrod (Solidago caesia)

    Part shade to Full Sun; Most well-drained soils, tolerates poor soil; 1.5 – 3 feet tall; Yellow; August – October

    Blue-stemmed goldenrod has yellow clusters of flowers that bloom all along the purplish-blue stem in early autumn, creating streaks of gold if planted in large patches. Unlike other goldenrods, it does not spread aggressively. Its leaves host larvae of 45 moth species (Gray and Booth 2024).

    Common Eastern Bumble Bee on Blue-stem Goldenrod.

    Button Blazing Star (Liatris aspera)

    Full Sun; Dry-Medium; Sand, loam; 2 – 5 feet tall; Yellow; August – October; Purple-Pink

    Button Blazing Star is one of the most drought tolerant blazing stars. Unlike Dense Blazing Star (Liatris spicata) its flowers are held on individual stems rather than in spikes and the corms cannot be divided. Birds especially prefer its seeds (Diboll and Cox 2023).

    Button Blazing Star provides nectar to migrating Monarchs in my garden on Sept. 2. It was still blooming on October 10th.

    The evening of October 9th we had a second hard frost (-6oC with wind chill) but the next day all of these native perennials were still blooming. If you are looking at your garden this Thanksgiving and not seeing any plants still flowering and supporting pollinators, maybe make plans to add one or two of these next spring?

    REFERENCES

    Booth, S. no date. Native Asters for Ontario Gardens.

    Diboll, N. & H. Cox. 2023. The Gardener’s Guide to Prairie Plants. The University of Chicago Press. 636 pp.

    Gray, R. and S. Booth. 2024. The Gardener’s Guide to Native Plants of the Southern Great Lakes Region. Firefly Books. 352 pp.

    St. John, K. 2023. A Closer Look at Sleeping Bumblebees. Outside my Window blog post.

    The Xerces Society. 2025. Bumble Bees: Nesting and Overwintering.

    RELATED

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    The Secret Life of the Eastern Bumblebee
    Fall Colour in Your Garden
    The Late Summer/Fall Garden
    Native Plants, Perennials, Shade Gardening

    Underfoot & Under-Valued? The Common Liverwort

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    By Mary-Jane Pilgrim, Master Gardener

    Umbrella liverwort (Marchantia polymorpha) is a fascinating plant that often catches the eye with its unique, umbrella-like structures. These small, flat, and green plants have been around for millions of years, making them one of the oldest plant species on Earth. They do not have a vascular system, and like ferns, they produce spores instead of seeds. While they do not flower, the female reproductive structures mature to look like tiny palm trees or umbrellas. For this reason, the common variety is called umbrella liverwort.

    In our area, umbrella liverwort is commonly found in moist, shaded areas like garden beds, greenhouses, and along stream banks. This plant is native to many parts of the world, including Ontario, and has a long history of thriving in damp environments.

    While liverwort is native, it can sometimes behave like an invasive plant, especially in gardens and greenhouses. It thrives in conditions where moisture is abundant, and air circulation is poor. If left unchecked, it can spread rapidly, covering the soil surface and competing with other plants for light and nutrients. However, its unique appearance and ancient history make it a cool plant to observe in your garden.

    If you want to manage umbrella liverwort, focus on improving drainage, reducing moisture levels, and allowing more sunlight into the affected areas. But for those who appreciate its prehistoric charm, umbrella liverwort can be a delightful addition to a garden, provided it’s kept in check. An added benefit is that you don’t have to plant them — they just show up!

    Bees & Pollinators, Butterflies and Moths, Myths, Native Plants, Shade Gardening

    Native Ontario Goldenrods for Your Garden

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    by Emma Murphy, Master Gardener

    The burst of bright yellow in our late summer gardens and surrounding countryside heralds the blooming of our iconic native goldenrods. Although there are more than 25 goldenrods native to Ontario, most people are familiar with Canada Goldenrod (Solidago canadensis), which is likely the tall one you see as you are out driving.

    I have lots of Canada Goldenrod in the naturalized back of my garden, but I also call it my garden thug, because it’s very happy there and trying to take over the world (or at least my backyard). First it outcompeted my New England Asters, and then started crowding out my newer planted trees.

    So I started exploring other, more well-behaved goldenrods to add to my garden that still bring all the benefits of this lovely plant, including acting as important nectar and pollen sources for many specialist pollinators and host plants for many moth and butterfly caterpillars. Goldenrods are important late season fuel for migrating butterflies (like monarchs) and our bumblebees.

    Here are 3 goldenrods that you should be able to find at native plant nurseries (and maybe eventually in our regular nurseries) that I am experimenting with in my garden.

    Zigzag Goldenrod (Solidago flexicaulis)

    I first saw this goldenrod in a local provincial park and fell in love with it because it thrives in shade/part shade! It can take fairly dry conditions and will grow up to 3 feet high. I’m told if it’s happy it will spread nicely by rhizomes and seed. The name refers to the “zigzaggy” form of the stems. Added bonus? It’s fragrant.

    Photo credit: Kirsten Johnson

    Bluestem Goldenrod (Solidago caesia)

    Another winner in my book (before it’s even flowered) because it also brightens up shade gardens, although this one prefers moister soils. Bluestem Goldenrod has graceful, arching stems and bright yellow flowers and can reach 3 feet tall – the name comes from the purplish stems. It will colonize over time by self seeding. Also known as Wreath Goldenrod.

    Photo credit: Tom Feild

    Stiff Goldenrod (Solidago rigida)

    This one’s a sun lover and can reach 5 feet; I’m trying it in my front garden bed with my New England Asters (Symphyotrichum novae-angliae), cup plant (Silphium perfoliatum) and false sunflowers (Heliopsis helianthoides) because it needs similar height plants to avoid floppiness. Unlike the bluestem goldenrod, this one is upright and has large oval leaves and a cluster of yellow flowers at the top of the stems.

    Photo credit: Dan Mullen

    The City of Toronto’s LiveGreen initiative has some excellent additional information on various other goldenrods here. There is one to meet whatever garden conditions (sun/shade; dry/wet etc) you might have. You can also grow some in containers!

    For those interested in more information on identifying and learning about goldenrods here are a few resources:

    Ontario Wildflowers – Goldenrods Group

    Ontario Wildflowers – Learn the Goldenrods

    Goldenrods

    Native Goldenrods for Ontario Gardens

    So what new goldenrods will you try in YOUR garden?

    Do Goldenrods Cause Hay Fever?

    And finally (because we’re always asked this question as soon as fall hay fever starts) no, goldenrods do not cause hay fever. Their pollen is far too heavy to be blown around in the wind – the real culprit is Common Ragweed (Ambrosia artemisiifolia) which is easily blown around by the wind and while native, will never find a place in our garden (my husband gets hay fever). NOTE: yes I acknowledge that some people are allergic to goldenrod but they have to literally stand beside them to get the pollen on them). I love what Horticulture Magazine has to say

    So why do we blame goldenrod instead of ragweed? Probably because goldenrod flowers are so showy. Ragweed’s green flowers are inconspicuous. It makes sense that people suffering from allergies suspect the plant that they can see is in full, abundant bloom.

    Horticulture Magazine

    Garden Design, Information, Native Plants, Perennials, Shade Gardening, Websites

    Gardening with Ferns

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    By Cheryl Harrison, Master Gardener

    Ferns are fascinating plants! They evolved more than 350 million years ago. Ferns and their allies were the most common plants during prehistoric times. Today, there are over 12,000 fern species growing everywhere except at the poles.

    Ferns are special in the gardening world. They are exotic and beautiful but not as flamboyant as many plants. We have developed a fern “dictionary” to describe them. For example, an entire fern leaf is actually called a frond and the stem is called a stipe. Ferns reproduce via spores which are not the same as seeds and ferns do not produce flowers. If you study ferns, you may be a pteridologist….oh my!

    Fern propagation means collecting spores or bulblets. Fern propagation, using spores or bulblets, is explained here . There is only one native Ontario fern that produces bulblets. It is the bulblet fern or Cystopteris bulbifera. The easiest way to obtain a new fern is, of course, to buy one. A list of local vendors is below. Some ferns spread via rhizomes or underground runners, just split the root with a sharp shovel and separate out the fronds of the new plant. You may also split ferns with fibrous roots as you would many perennials, once they reach an adequate size, again using a sharp shovel. You may split then plant ferns in the spring or fall. Check out your friend’s gardens…you may find a fern, or two, growing that your friend may be willing to share. Please do not harvest from the wild. Some fern species no longer grow in the wild because of over harvesting.

    Maidenhair fern (Adiantum pedatum), Author’s garden

    Ferns may be used in your garden as an exclamation point or a secret quiet spot, mixed in with your other shade loving perennials or in a woodland garden. I have some ferns mixed in my gardens now but 2021 is the year that I plan to tackle the creation of a woodland garden. I have already put in an order for some ferns including the bulblet fern (Cystopteris bulbifera), ghost fern (Athyrium X Ghost) and the ostrich fern (Matteuccia struthiopteris). This grouping should work well together because they all prefer shade or part sun and moist soil with lots of organic matter. I plan to amend their location with compost and to mulch after planting to maintain moisture and reduce weeds. These plants are perennials so I will expect to see them again next year.

    Ferns are beautiful plants whose graceful, arching fronds would make a great addition to your garden!

    Resources

    American Fern Society

    Ontario Ferns

    Peterson Guide to Ferns, Houghton Mifflin Harcourt; Second Edition (Sept. 26 2005), ISBN-10: 0618394060

    Where to Buy Ferns

    Gardens Plus, Peterborough

    Ground Covers Unlimited, Bethany

    Native Plants in Claremont

    Please support your local nurseries. Many of them, including those listed above, carry the more unusual plants that you will not likely find at the big box stores.

    Advice, Bulbs, Links, Native Plants, Perennials, Shade Gardening, Websites

    Spring Ephemerals

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    By Cheryl Harrison, Master Gardener

    Definitions of “spring” and “ephemeral”, curtesy of Merriam-Webster online dictionary, are “to come into being” and “lasting a very short time”.  Two wonderful words, when used together, mean those lovely but short-lived flowers that we may see on our walks through woodland gardens or deciduous forests at this time of year!

    My list of favourite spring ephemerals includes:

    Trillium (Trillium grandiflorum) – Of course, this native plant comes to mind first.  It is Ontario’s official flower but not Ontario’s only trillium … there are four other native species. Trillium grandiflorum produces one large, white, three-petaled flower above three, simple, broad leaves.  The flower fades to pale pink as it ages.  Red seeds are produced which are mainly dispersed by……ants!  Seeds germinate slowly and take 4-5 years to become a mature flowering plant.  Plants grow to reach 30-45 cm (12-18 in.) high, prefer moist rich soil and dappled shade.

    trillium
    Trillium grandiflorum

    Dog-toothed violet (Erythronium americanum) –  These pretty little native flowers grow from a corm.  They are small, just 15 cm (6 in.) high but their bright, yellow flowers stand out  and along with their spotted leaves (hence their other common name “Trout Lily”), are one of the earliest spring ephemerals to appear.  They prefer rich, moist but well-drained soil and part to full shade.

    dogtooth
    Erythronium americanum

    Bloodroot (Sanguinaria canadensis) – If you remember your high school latin, you will recognize where Sanguinaria originates when you learn that all  parts of this native contains an orange/red juice.  The Latin sanguinarius means “bloody”.  S. canadensis is the only species in this genus.  It produces a white flower, that may be tinged in pink, and has deeply lobed, flat leaves.  It prefers part to full shade and well drained, moist, rich soil but seems to survive in varying soil conditions.  This plant will grow under your black walnut tree!  S. canadensis grows 15-30 cm (6-12 in.) high and spreads through rhizomes.

    bloodroot
    Sanguinaria canadensis

    Mayapple (Polophyllum peltatum) – Mayapple makes a great groundcover.  It grows up to 45 cm (1.5 ft.) tall and produces one white flower which appears under it’s umbrella-like, multi-lobed, two leaf foliage in late spring…..a single leaf means no flower and no fruit.  The leaves and root are poisonous as is the immature green fruit.  Only the mature yellow fruit is edible.  This plant spreads through rhizomes, prefers light shade and moist, rich soil.

    mayapple
    Polophyllum peltatum

    Jack-in-the-pulpit (Arisaema tryphyllum) – Where do I start; this plant has a very interesting flower …. the spathe is the most conspicuous part.  It is a hooded, tube-like structure and houses the spadex which is a spike and is where the actual flowers are located.  Clusters of bright, red berries form in the fall.    It grows 30-90 cm (1-3 ft.) tall and prefers moist, rich, slightly acidic soil and part to full shade.  Jack-in-the-pulpit grow from corms.

    jack
    Arisaema tryphyllum

    Next time you go for your woodland walk look for the spring ephemerals.  Their appearance signals that warmer weather is coming very soon!  Let the gardening season begin!

    Many nurseries now carry native plants and some specialize in natives.  Just be sure to ask about the origin of the plants that you are buying, you are looking for plants that have been nursery propagated not harvested from the wild.

    Suggested Nurseries

    Resources

    Books

    • The Ontario Naturalized Garden, by Lorraine Johnston ISBN1-55110-305-2

    Websites

     

    Holidays, Perennials, Shade Gardening, Websites

    The Christmas Rose: Helleborus niger

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    By Judy Bernard, Master Gardener

    Nothing warms a home up as much as plants do. At this time of the year there are so many options to choose from: Poinsettias ranging in colour from white to deep reds, Cyclamen, Christmas Cactus, Amaryllis, Rosemary to name a few. There is one, however, that is usually found in garden centres in the spring but which one can occasionally find in a grocery store or florist in the fall, and that is the Christmas Rose. Its botanical name is Helleborus niger and its common name is Hellebore.

    Helleborus niger is a hardy perennial in the Raniculaceae or buttercup family. It has dark green evergreen foliage and delicate white flowers resembling a wild rose. They are hardy to zones 3-4. Bloom times vary from November to February/March, depending on the location. They like semi-shade and grow well in sheltered areas in well-draining soils.

    If you are fortunate enough to find one in your local store, not only will you have a conversation piece, you will be able to plant it outside in your garden and enjoy it for many years.

    Links:

    Photo credit: Sue Flinders Adams: After being purchased in a  grocery store in November/December, it was planted at Portage Lakehouse, Haliburton and bloomed under the ice and snow the following spring. Picture taken April, 2017.

    Garden Design, Health, Light, Native Plants, New Gardens, Perennials, Shade Gardening, Shrubs & Trees, Sun Gardening

    The Light in Your Garden

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    by Chris Freeburn, Master Gardener

    Growing any plant successfully in your garden depends on many factors and an important one is the amount of light you get throughout the day. Growing Hosta out in the blazing sunshine is fine when they first emerge in springtime, but most Hosta will fry with the hot summer sun all day long. A peony without enough sun will have lovely green leaves, but will probably not give you any flowers.

    Take a day or two to notice when your flower beds are in sun and for how long. Full sun means at least 6 hours of sun a day. Full shade means no direct sun. Part sun should only be about 3 hours. Morning sun is the best as it is not harsh and hot like late afternoon sun, so if you have gardens facing east, you have the best light for most plants.

    3

    Knowing which direction your home sits is important too. Get your orientation fixed in your mind. Remember that trees and buildings will shade the gardens as the sun moves throughout the day. As the seasons change, the sun will move slightly in its orientation and where the sunlight comes from will change. Be prepared when you go plant shopping, read plant tags and talk to experts to be sure you are putting the right plant in the right place for the right light requirements.

    Like growing just outside your garden growing zones, gardeners can also grow outside sun requirements. Hybridizing has enabled us to have plants that will grow outside their normal light needs. For instance, there are now Hosta that will take a lot of sun. Try to stretch the limits if you want that certain plant in that certain place, but remember to monitor it to be sure it is not being stressed and is performing at its best.

    1

    Lighting may change in your garden. If a big tree is removed, a full shade garden can become a full sun garden. As a tree grows in your or your neighbour’s yard, or if a new building goes up, it will become more shaded. You may find that you will have to relocate plants when this happens.

    Spend more time in your garden, just watching. It is good for your education and good for your soul.

    Annuals, Bees & Pollinators, Birds, Books, Bulbs, Children, Compost, Garden Design, Health, Herbs, Houseplants, Links, New Gardens, Perennials, Planting, Pruning, Seeds, Shade Gardening, Shrubs & Trees, Soil, Tools, Uncategorized, Vegetable Gardening, Weed Control

    The Peterborough Garden Show

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    By Mary-Jane Pilgrim, Master Gardener

    It’s coming in 25 days.  It can’t come soon enough.  In our city, “The Garden Show” is a true sign of spring.  It’s an occasion that brings together speakers, workshop leaders, vendors, horticultural society members, master gardeners, exhibitors and many others for one reason:  “For the Love of Gardening”.PGS-logo-small

    This year marks the 19th fantastic show: 
    April 26 – 28, 2019 (Friday 5-9pm, Saturday 10am-5pm & Sunday 10am-4pm).

    And there’s great news ! The show has MOVED – to Fleming College’s brand new Trades and Technology Centre on Brealey Drive with lots of FREE parking and a $10, one-price ticket so you can enjoy the show all weekend.

    The Peterborough and Area Master Gardeners will have a booth at the show, and will be happy to answer any gardening questions that you may have. Watch for our red aprons!

    The theme “Coming Up Roses” is reflected in several of the amazing speakers along with educational and fun workshops and demos.

    This award-winning show was honoured in 2017 with both a “Canada 150 Garden Experience”, and “Garden Event of the Year” by the Canadian Garden Council, so come and see what all the fuss is about.

    You will find many of your old favourite vendors along with some new ones.

    …and don’t forget the popular “Little Green Thumbs” Children’s Garden that is always teaming with liveliness and action! There are learning activities, face painting, crafts and even a take-home project. Their theme this year is “Miniature Gardens for Elves and Fairies”.

    All the show profits go back into our community to fund scholarships for post-secondary students studying in horticulture-related fields,various local projects & Community Gardens.  Since 2002, the show has put over $200,000 back into our community.

    Please save the date, visit and and learn why “Everything’s Coming Up Roses” in 2019.

    Learn more about the incredible speakers, workshops, bus trips, places to stay and tickets here: peterboroughgardenshow.com.

     

    Allelopathy, Compost, New Gardens, Perennials, Planting, Pruning, Shade Gardening, Shrubs & Trees, Soil

    Truth or Fiction? Are Black Walnuts Toxic in my Garden?

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    by Emma Murphy, Master Gardener

    As a Master Gardener, one of the most common questions I get asked is about the toxicity of walnut trees (Juglans nigra).

    “Well I heard that the juglone stuff in the roots kills everything and that I can’t plant anything under or anywhere near a walnut tree.”

    Well yes Virginia, you can plant a garden under a walnut tree, and have it thrive. Let’s look at Exhibit 1 below – an established perennial bed under a walnut tree. It’s at our house, so I guarantee it’s real, and it’s been there since late 2007.

    BP4

    Lots of lovely perennials here – hostas (Hosta spp.), daylilies (Hemerocallis), bearded iris (Iris germanica), summer phlox (Phlox paniculata), wild ginger (Asarum canadense), purple coneflower (Echinacea purpurea), ditch lilies (Hemerocallis fulva), although those last ones are doing just a little too well LOL. Don’t believe it’s a walnut tree? Here’s a photo from a bit further back on the street.

    BP1

    Yes, she’s a big old lady – we think she was planted around the same time the house was built, making her about 140 years old. I think she’s getting a bit tired out – most years she doesn’t produce too many walnuts. Her slightly younger cousin is to the left of the barn in the background – LOTS of walnuts off her (and yes a garden under that one too).

    So where does this fallacy come from that ‘nothing grows under a walnut’? Well certainly all parts of the walnut tree contain a chemical called juglone (heck it’s even in the Latin name!). Juglone is a chemical that affects other plants growing nearby (a phenomenon called allelopathy). Simply put, allelopathy involves “living or dead plant parts that release chemicals into the soil which have an effect on other plants—positive or negative.” For walnuts it seems like an attempt at self preservation, with juglone acting like a natural herbicide on other plants.

    As Professor Linda Chalker-Scott explains in her recent (2019) peer-reviewed Washington State University Extension paper, damage to tomatoes and other crops near walnut trees in the 1920s caused people to believe that toxic chemicals were involved, and this perception persisted and became widespread despite there being no evidence (and this was before social media existed!). The US Department of Agriculture did field testing – no problems. When applied in a laboratory setting to seeds and seedlings it did cause stunting, wilting, and necrosis, but the specific way it did this was unclear. The most recent science suggests that juglone disrupts photosynthetic and respiratory pathways and interferes with water uptake in plants.

    Picture1

    So! It does affect plants – the laboratory says so. Well yes, and no. Field tests do not support the laboratory work, which doesn’t accurately mimic real life conditions in your average residential garden (again, for more detail read the excellent paper referenced above). Two very old University Extension papers (1973 and 1993) continue to be used to state which plants are ‘sensitive’ and which are ‘tolerant’. However these were simply observational papers—meaning that they correlate the presence of walnut trees with damage to other species but do not confirm a causative relationship. Neither should be considered good scientific evidence.

    Gardening With Walnut Trees – My Story

    I am sure the scientists, arboretums, farmers, and garden writers will continue to debate this topic for a while. Meanwhile, here’s our story. In 2007 I wanted a garden bed under our black walnut in my front yard. At the time I had heard the walnut horror stories, so I thought – well, how about I just don’t disturb the roots of the tree? (not a good thing to do when establishing any garden beds under a tree). I put good topsoil and compost down, making sure to minimize tearing up of the soil and roots, and planted, and watered, and waited. Things grew. Winter happened. Next spring plants came up. For the most part I just moved perennials that were already on site, although some hostas were new. Here’s the garden in 2008 in the fall.

    BP5_plants_2008

    Fall asters (Astereae spp.), sedums (Sedum ‘Autumn Joy’ in this case), hostas (Hosta spp.), wild ginger (Asarum canadense), fall rudbeckias (Rudbeckia fulgida and triloba), purple coneflower (Echinacea purpurea), ninebark (Physocarpus opulifolius), iris (Iris spp.), astilbe (Astilbe spp.), sweet woodruff (Galium odoratum), Ozark sundrops (Oenothera macrocarpa), coral bells (Heuchera spp.), cranesbill (Geranium spp.). All doing just fine.

    And 2009 below, in the spring. Irises (Iris spp.) lemon lilies (Hemerocallis lilioasphodelus), lungwort (Pulmonaria spp.), poppies (Papaver rhoeas), ditch lilies (Hemerocallis fulva), variegated solomon’s seal (Polygonatum odoratum ‘Variegatum’), bracken (Pteridium aquilinum), bleeding hearts (Dicentra spectabilis), daylilies (Hemerocallis spp.).

    BP6_plants_2009

    Certainly, planting in general under walnuts is challenging – they cast dense shade and have extensive, water hungry root systems. Watering after establishment and for the first season is critical. We also had our walnut tree pruned professionally (it needed it) so it actually gets decent sunlight in the latter part of the afternoon. Like any fruit or nut tree they are messy, from their spring pollen to their leaves and nuts…oh those nuts.. 2017 was a crazy year – buckets of walnuts (I even had to engage my neighbours’ lovely children from across the street to help collect them) to 2018, with almost no walnuts. My trees are old too – although well pruned, their leaves drop at that first hard frost. 1

    In Defence of Walnut Trees

    Black walnuts are not all bad, and I will continue to treasure them in my yard. They are an amazing shade tree, are highly valued for their fine grained dark wood (for furniture), a great food source for wildlife and birds, and my white breasted nuthatches’ favourite spot to hide their seeds.

    We have definitely had our challenges with our walnut trees, and I’ve learned a great deal over the past 20 years. But one thing I know – I can garden with them around. You can too.

    Note: Black walnuts are not the only tree that produce juglone – other members of the Juglandaceae also produce it as well as hickory trees. Butternut, English walnut, bitternut hickory, pignut hickory, pecan, shagbark hickory, mockernut hickory are in the same family.