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, Soil

The Dark Side of Landscape Fabric

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By Carol Anderson, Master Gardener in Training

Over the years I have worked in many gardens with challenging microclimates, as well as those with challenging conditions such as poor drainage, drought, lack of sunlight, windy and excessively dry, and gardens with poor soil structure. However, the most challenging situation I have personally had to contend with was a garden that was “smothered” in landscape fabric. Although well-intentioned gardeners often utilize landscape fabric to control excessive weed growth in garden beds … the end result is most often the creation of a “garden catastrophe”.

Don’t get me wrong — landscape fabric has some applications that can make the garden more esthetically appealing and easier to manage, however its use should be largely limited to acting as a barrier under rock formations and/or stone installations where plants and weeds will never call home! In any other application, the result is hard packed, poor soil, unmanageable weed infestations and ultimately limitations in the natural growth and health of plants. Understanding the natural composition of soil and the cycle of life that occurs in the dirt and how this creates a natural environment conducive to plant growth will perhaps aid in understanding why landscape fabric is an enemy. 

Soil … the essence of life for plants. Soil is a mixture of mineral and organic material that is capable of supporting plant life. The ideal soil composition is 45-48% minerals, 2-5% organic matter and 50% pore spaces (filled with ~25% air and 25% water). As plant matter decomposes, it is worked into the soil by insects and other organisms. Through this process, the soil is continuously fed the nutrients needed to sustain plant life and air spaces are created which ensure water and nutrient availability to plant roots. Microorganisms in the soil contribute as well to ensuring nutrient availability and uptake for plants.

Landscape fabric halts this process by preventing the natural mixing of decomposing organic matter into the soil, resulting in hard-packed or poor quality soil. Good soil looks soft and crumbly. Poor soil looks either compacted and hard or very loose (such as sandy soil). Both of these soil conditions prevent plants from accessing water and nutrients in the soil. This picture depicts the poor soil structure and composition discovered in a garden after years of landscape fabric use. The was no evidence of organic matter and a lack of insects and worms that would be normally found in garden soil. As a result, the plants were weak, small, and nutritionally deprived.

If you are not yet convinced, let me also dispel the myth that weed growth is halted by the use of landscape fabric. While it may reduce the number of weeds in your garden initially, the ones that do thrive become entangled in and under the fabric. The removal of the weed bed that is embedded in the fabric becomes a nightmare to try and accomplish without destroying the rest of the garden. In addition, the organic matter and mulch used on top of the fabric facilitates weed growth, the roots of which ultimately penetrate the landscape fabric. Often the plants that you love also become embedded in the fabric as they try to grow and reproduce without the space to allow them to spread naturally.  

Websites

A Banner Year for Bunnies

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By Lois Scott, Master Gardener

The bunnies have been thick in my garden this summer.  We have seen wave after wave of adorable but hungry juvenile rabbits that have made the chipmunks look like garden angels!

According to Wikipedia the Eastern cottontail habitat “includes open grassy areas, clearings, and old fields supporting abundant green grasses and herbs, with shrubs in the area or edges for cover”.  This, including the neighbours’ property and the adjacent park describes the habitat around my home. 

This article by the Halton Master Gardeners describes two general strategies for protecting your plants from being eaten by rabbits and rabbit (and deer) resistant plants.  They suggest physical barriers and bad smell or taste:

Click to access deer-and-rabbit-resistant-plants.pdf

Hardware cloth (wire-based) is my go-to for plant protection.  I have it around young trees and shrubs year-round to protect them from winter browsing.  I have chosen to protect certain herbaceous plants in my garden by using hardware cloth and other more ‘creative’ barriers such as my ‘lashed together’ log cabin to protect a cylindrical liatris that the rabbits can’t get enough of.  If you are fencing a garden rather than a plant the fencing should be at least 2 feet high and sunk vertically into the ground at least eight inches.  Rabbits dig! 

Hardware cloth deters rabbits

This site https://www.torontowildlifecentre.com/wildlife-emergency-rescue-hotline/conflicts-with-wildlife/common-rabbit-problems/keep-rabbits-out-of-your-garden/  also recommends ‘scaring’ away rabbits by “placing unfamiliar visual stimuli around the yard such as shiny pinwheels, beach balls or foil balloons” or “mesh bags filled with pet fur or human hair hung at rabbit eye level” as long as there isn’t a rabbit nest close by as it may cause the mother to abandon the nest.  I think I may prefer the rabbits!

More creative “log cabin” used to protect rabbit-preferred plants

When it comes to what plants might be rabbit resistant, remember that these plants are only resistant, not foolproof.   I guarantee the rabbits haven’t read the list and when growing bunnies are hungry, they become less selective. 🙂

My garden is looking very full at this time of year so in spite of missing significant parts of certain plants the damage is not really noticeable when looking at the garden as a whole.  Rabbit populations go up and down so next year I may be wondering where all the bunnies are.

Garden Design, Perennials, Websites

Low Maintenance Gardening

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By Marilyn Homewood, Master Gardener

Sound too good to be true??  Years of trial and error on a property with a (shallow) dug well has taught me the value of adequate bed preparation for long term success of the landscape garden that consists primarily of perennials, shrubs and bulbs (with the odd annual and biennial tossed in).  I have large landscape beds and could not keep up without some kind of strategy. 

It may seem somewhat discordant to be discussing bed preparation in July but a little planning and preparation can go a long way towards achieving a garden that requires less maintenance, is easier to work in, requires little to no supplemental water or feeding all while looking attractive. The solution lies under our feet. 

My beds have all been dug to a depth of 18 inches.  This one time initial dig allows for loosening of compacted earth, removal of rocks (or boulders) and generous amendment of the soil with organic matter such as rotted manure or leaf or mushroom compost. This preparation will allow plant roots to reach deeper into the earth (especially those with large fibrous roots or tap roots) where residual moisture is still available during drought. Plants will become more resilient and able to survive on the rainfall alone.  In my garden, I have not watered the landscape beds since they were begun with the exception for first year plants that are getting established.  In dry spells, the blooms may be somewhat smaller but are still found in abundance.   

Coneflowers blooming well despite drought

The loosening of the soil also creates a better-draining soil makes it less likely that plants become water-logged or oxygen-deprived in those times when water is abundant.  This also minimizes loss of plants/bulbs to rot.   

The use of organic matter amendments helps the soil to retain the water that is provided by the rainfall by increasing the porosity of the soil.  And finally, an application of a thick layer of mulch (I use shredded bark) on the surface of the soil helps prevent evaporation of moisture from the ground and well as inhibiting the greedy weeds that will compete for moisture.

Second year delphiniums are 6-7 feet despite no water

Organic matter (OM) amendments provide a number of other benefits which ultimately gives healthy plants while saving us labour.  It enhances soil structure which increases the porosity of the soil leading to improved water infiltration, better drainage/aeration and help soils to resist compaction.  This makes soil more friable and easier for the gardener to work in as well as easing root penetration in the soil profile.  

OM helps to store and supply macronutrients (ex. nitrogen) and makes micronutrients (calcium, magnesium and potassium) available to the plant by increasing the soils’ ability to hold onto these elements (prevents leeching).  Also binds metal micronutrients (iron, aluminum, zinc, copper, manganese) and increases their availability to the plant.  All this means that your need for chemical fertilizers will be reduced or not required. 

Despite my best efforts, I had to make a succulent only garden in a difficult spot

OM also enhances soil microbial diversity that assists in the suppression of disease so plants are healthier. 

Deep beds mean deep roots; improved soil structure means better drainage and water holding capacity; increased biological activity mean more nutrients released for plant use and microbial diversity means less disease.  The result is healthy, vigorous plants that need less watering, less additional feeding/supplementation and less treatment for disease. 

Resources: 

Cornell University Cooperative Extension, Agronomy Factsheet 41, “Soil Organic Matter”, http://franklin.cce.cornell.edu/resources/soil-organic-matter-fact-sheet 

Leslie Cooperband (2002), “Building Soil Organic Matter with Organic Amendments” University of Wisconsin-Madison, 

Lois Berg Stack (2016), “Soil and Plant Nutrition: A Gardener’s Perspective” University of Maine Cooperative Extension: Garden & Yard, https://extension.umaine.edu/gardening/manual/soils/soil-and-plant-nutrition/ 

Annuals, Dreams, Garden Design, Garden rejuvenation, New Gardens, Perennials, Research

Gardening in July

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by Cheryl Harrison, Master Gardener

July is the month that I tend to really enjoy the garden….most of the work is done! The planting of seeds, and plants into pots and garden beds, dividing and thinning and garden creating is behind me for now. However, there are still a few garden tasks.

I try to keep up with weeding because weeds can quickly overrun your garden as they begin to set seed. Weeds take nutrients from the soil which your plants need and can smother out young plants. And I am one of those gardeners who enjoys weeding. I feel a great sense of accomplishment when I finish weeding a garden bed and when I pull out a weed and get the root….well that is simply thrilling.

Early July is a good time to trim back your annuals in order to encourage bushier growth and to trim off the spent blooms of your perennials to prevent seed production and allow the plant to put its energy into its roots. You may want to start fertilizing your potted plants because any fertilizer that was contained in the potting soil has probably been used up by now. There are lots of choices when it comes to fertilizers so talk to the staff of your favorite local nursery. They will be able to advise you and will likely carry the best products.

July is also the month when that garlic that you planted last fall is ready to harvest. We grow hard neck garlic that a kind neighbor started us on a few years ago. I removed the curled scapes last week and froze them for future use. I will keep an eye on the leaves on the garlic because when a few leaves have started to turn brown then the garlic is ready to harvest.

The rest of your vegetable garden may be starting to produce now as well. We have harvested some tomatoes already which is a bit earlier than usual for us. It is a good idea to check your vegetable garden daily so that you harvest and enjoy the results at their peak and to respond quickly to any issues that may arise.

I evaluate the appearance of my ornamental gardens in July. It is interesting to see if the garden looks the way that I had planned. I do not mean, “is it perfect” but how close is it this year to the feeling that I would like to achieve when someone walks through the gardens for the first time. I look at how the colours and textures work together. I ask myself if there are any bare spots or areas that I will need to renovate soon (eg. crowded and/or overgrown plants).

I am starting to plan my fall and next spring projects now. This year, two smaller gardens were joined and planted with mainly annuals for quick impact. I know that I plan to fill this garden with perennials and native woodland plants. This means keeping this garden in mind when I am shopping at the local nurseries.

Spring, and early summer, gardening can be a very busy time. July is the month to really enjoy your gardens and dream about what you might like to do next!

Insects, Vegetable Gardening

How Chemistry Plays a Role in Plant-Insect Relations in our Gardens

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By Laura Gardner, Master Gardener

Have you ever wondered how certain insects are able to discover a plant in your garden? How do they know it is there? Some of them may already have been hanging out there but others fly in from afar. How does a predatory insect seem to find its prey without much effort? Both insects and plants engage in the production and release of chemicals such as pheromones and allelochemicals. These can act as insect attractants and deterrents. 

Last year I grew Tomatillos. I usually grow Tomatoes but I thought I would try Tomatillos instead. One of my plants was visited by Three-Lined Potato Beetles (Lema daturaphila). These insects feed on plants in the Solanaceae family such as Tomato, Potato, Eggplant, Tomatillo, and Groundcherry. From my reading, this species is not very damaging so I was willing to monitor and see if beneficial insects would step in to act as biological control agents. Sure enough, soon afterwards, when I was inspecting my plants, I found an assassin bug eating the beetle larva that were under a leaf. Just like Lily Leaf Beetle (Lilioceris lilii) larvae, the Three-Lined Potato Beetle larvae cover their backs with their own excrement called a “fecal shield,” as a means of defence. Clearly the assassin bug was undeterred.  Plant volatiles had likely been released by the plant in response to the larvae feeding damage to the leaves. This has been described as an indirect defence mechanism[i].” The assassin bug responded as it detected the plant volatiles.

This spring, I planted some cantaloupe and watermelon seedlings in a raised bed. I read up on the various insects that are attracted to these plants—their life cycles and behaviours. One of the insects that favours cantaloupe and other members of the cucurbit family is the Striped Cucumber Beetle (Acalymma vittatum). Up until recently, I hadn’t seen any on my plants. Often, I will use floating row covers for protection from insect damage but these plants are currently flowering so they are uncovered so pollinators can access them. When I saw my first beetle, I thought about how it knew I was growing cantaloupe. Cucurbit plants emit floral volatiles in the air that travel. Adult cucumber beetles are attracted because the pollen of the plants makes up a part of their diet.[ii] These same and other volatiles also attract pollinators of these plants such as Squash Bees (Eucerini spp.).[iii]

Cucurbit plants also contain a chemical called cucurbitacin. This is the substance that gives some cucurbits a bitter taste. When cucumber beetles feed on the leaves and other parts of the plant, they absorb the cucurbitacin, rendering them unpalatable to many predators. Young plants produce more cucurbitacin than older plants—which make them more attractive and vulnerable to damage.[iv] Cucurbitacin is so attractive to the beetles that it encourages more and more feeding—called a “phagostimulant.”[v] (Is this the same as sugar, salt, and fat for us humans?) As the beetle feeding progresses, adult male beetles give off an aggregation pheromone called vittalactone that invites others to come and join the party.[vi] Cucurbitacin also plays a role in their reproductive activities as males transfer it to the females as “nuptial gifts.”[vii]

The beetles can also transmit bacteria via their feeding that causes a fatal wilt in the plant. What is also unfortunate is that the wilting plant gives off more volatiles that attract more beetles. The flowers of wilting plants are not as attractive as non-wilting plants—this encourages the beetles to move on to other nearby plants, thus causing further spread of the disease.[viii]

In the end, the key is to try to deter adult beetle feeding as much as possible. This can be achieved in a number of ways such as using floating row covers; delaying planting in the spring; planting more developed transplants; hand-picking beetles in early evening when they are most active; planting cucurbit varieties with lower levels of cucurbitacin,[ix] interplanting plants like radishes and nasturtium with melons,[x] and using straw mulch around plants to attract beneficial wolf spider predators.[xi] Some cucurbits like watermelon are resistant to bacterial wilt,[xii] unlike cantaloupe. So perhaps by the end of the summer I will at least have watermelon.

[i] Dicke, M. (2009), Behavioural and community ecology of plants that cry for help. Plant, Cell & Environment, 32: 654-665. https://doi.org/10.1111/j.1365-3040.2008.01913.x

[ii] Rojas, Erika Saalau et al. Bacterial Wilt of Cucurbits: Resurrecting a Classic Pathosystem. Plant Disease 2015 99:5, p. 569. https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-10-14-1068-FE

[iii] Andrews ES, Theis N, Adler LS. Pollinator and herbivore attraction to cucurbita floral volatiles. J Chem Ecol. 2007 Sep;33(9):1682-91. doi: 10.1007/s10886-007-9337-7. Epub 2007 Jul 21. PMID: 17659427.

[iv] Rojas, p. 569.

[v] Wallingford, Anna. What Cucumber Beetles Want. Over Informed on IPM. August 13, 2020, Episode 24. https://extension.unh.edu/blog/2020/08/over-informed-ipm-episode-025-what-cucumber-beetles-want

[vi] Ibid.

[vii] Rojas, p. 569.

[viii] Alexander, Lauren Maria. Take Control of Cucumber Beetles. Growing Produce. https://www.growingproduce.com/vegetables/take-control-of-cucumber-beetles/

[ix] Ibid.

[x] Cline, G. R., Sedlacek, J. D., Hillman, S. L., Parker, S. K., & Silvernail, A. F. (2008). Organic Management of Cucumber Beetles in Watermelon and Muskmelon Production, HortTechnology hortte, 18(3), p. 444. https://doi.org/10.21273/HORTTECH.18.3.436

[xi] Striped and Spotted Cucumber Beetle: Insect Pests of Vegetable Gardens. Kansas State Research and Extension. https://bookstore.ksre.ksu.edu/pubs/MF3545.pdf

[xii] Rojas, p. 565.

Advice, Annuals, Websites

Begonias, so many Options!

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By Christine Freeburn, Master Gardener

The choices for summer annuals seems to grow greater every year. Filler plants like geraniums, petunias, marigolds, impatiens are lovely, but the begonia has so many variations of shapes, sizes, colour, and sun requirements, they are worth a try in your hanging baskets or containers.

Begonia are generally easy care with no deadheading and different varieties can grow in sun or shade. Flowers are often smaller but there are lots on the plant. They often just fall off or can be pinched off quickly. Leaves come in many shapes and sizes, colours and textures. When you go into a garden centre, you need to know what type of begonia you are looking for.

Fibrous rooted types include the easy Dragon Wing variety which are great in window boxes and containers. They come in red, pink or white, grow about a foot tall and wide, and can take sun or part sun. There is a new variety called Canary Wing which has yellow leaves and prefers less sun.

Wax begonias Begonia semperflorens are usually sold in cell paks, prefer part shade, can have bronze or green thicker fleshy leaves and white, pink or red flowers. Often called bedding begonia, they are great in the garden as an alternative to impatiens.

Tuberous begonias include the Solenia type Begonia x tuberhybrida which can take full sun and come in a variety of colours from shades of pink to yellow and red. Great in hangers or containers.

Solina begonia

‘Nonstop’  and ‘Illumination’ are  hybrid variety of tuberous begonia that will take the heat but want shade. They come in lovely shades of pink, red, yellow, peach or white. These also work well in containers and hangers.

Reiger begonias can produce double blooms, are more upright and also prefer shade.

Gryphon Begonia is a cane type begonia with stunning foliage and upright habit which will do well in part shade in the garden bed. Although the plant rarely flowers, the maple shaped leaves on a 2 foot plant looks great.

Rex Begonias have amazing furry leaves in many different shapes and colours. They do not want any sun and are often used as houseplants. Flowers are rare on these lovely specimens, but the leaves are the showstopper.

Rex begonia

And if you grew houseplants in the 70s, you might also remember the cute little indoor begonia called Strawberry Begonia Saxifraga stolonifera which grows similar to the spider plant having babies growing from trailing stems. These little houseplants are difficult to find but a nice addition to a houseplant collection.

Although begonias don’t need constant deadheading like so many other annuals, removing spent blossoms will keep the plant looking fresh and encourage new blooms.

Soil should be well draining and evenly moist but don’t over water as this can lead to root rot. Begonia stems are fleshy and brittle, and can break easily, so they don’t do well in wind. Fertilizing for bloom and good health can be done weekly over the summer months.

http://www.missouribotanicalgarden.org/

https://www.thespruce.com/

Advice, Perennials, Propagation

Peonies: The Stars of the Show at Present

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By Mary-Jane Pilgrim, Master Gardener

Peonies are like the royalty of the flower world, with their lush petals and captivating fragrances. If you’re itching to grow more of these stunning beauties in your garden, you’re in luck!

Peony plants fall into one of three categories: herbaceous peonies, tree peonies, and intersectional/Itoh peonies (modern crosses between herbaceous and tree types). This article addresses the propagation of herbaceous peonies by seed and by division.

  1. Growing Peonies from Seeds: Starting peonies from seeds is like embarking on a rather long gardening adventure. First, collect ripe seeds from mature peony plants once the flower heads have dried. Give them a good soak in water for a day to help with germination. Then, plant the seeds in well-draining soil in a pot or tray. Cover the container with plastic wrap to create a cozy greenhouse effect.

Now, it’s time for a little winter simulation. Pop the container in a cool spot like your fridge for about three months. After the chill period, move the container to a warmer spot with indirect sunlight. Keep the soil moist, and be patient. It might take a while, but soon you’ll see those precious seedlings sprouting. Once they grow bigger, you can transplant them into individual pots or your garden. Remember, it may take a couple of years for them to bloom.

  1. Dividing Peonies: Dividing peonies is like giving them a fresh start and making more peony magic happen. Autumn or early spring is the perfect time to divide these beauties. Carefully dig up a mature peony plant, making sure to keep as many roots intact as possible. Gently shake off excess soil and look for natural divisions or “eyes” on the plant – these are the points where new shoots will emerge.

Grab a clean and sharp knife, and cut the plant into sections, making sure each division has a few healthy roots and eyes. Then, replant these divisions in well-prepared soil in a sunny spot. Give them a good drink of water and watch as they settle in and grow. Don’t be surprised if it takes a year or two for the divided peonies to bloom, but when they do, it’ll be worth the wait!

With these two propagation methods, you can expand your peony collection and enjoy a blooming paradise in your garden. Whether you choose seeds or division, the joy of growing peonies will reward you with breathtaking blossoms and a sense of accomplishment. Happy gardening!

Bees & Pollinators, Perennials, Propagation

Why are my Columbines Changing Colour?

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by Emma Murphy, Master Gardener

Columbines (Aquilegia spp) are lovely perennials. I have had them in my garden for many years, and they always offer a pop of colour in the late spring/early summer garden here in Lakefield, Ontario.

These easy care perennials come in a variety of colours, shapes and sizes – most are bi-coloured, ranging from pastel shades to vibrant hues. Columbines have distinctive five-petaled flowers with long backward-extending spurs as pouchlike extensions of the petals, containing nectar. Sepals and petals are brightly coloured. The leaflets of the compound leaves are usually rounded and notched.

In my garden I have both cultivars and straight species (native) columbines, but it was a query on our Master Gardener of Ontario’s Facebook page about someone’s columbines changing colour from year to year that caused me to go down the research rabbit hole to try and find an answer for them.

What Did I Find Out?

Well, apparently columbines really like to hybridize with other columbines. They really do. They are also sensitive to their soil conditions and a number of other factors.

There has been some fascinating research done at universities like UC Santa Barbara (here and here). In one study they used two columbine varieties – red columbines pollinated by hummingbirds, and white or yellow columbines pollinated by hawk moths. Apparently hummingbirds prefer medium length nectar spurs (the ‘tails’ on the columbines), while hawk moths prefer the relatively longer-spurred species.

A. formosa (left) is primarily pollinated by hummingbirds. A. pubescens (right) is primarily pollinated by hawk moths.
Source: https://people.eemb.ucsb.edu/ballerini/evangeline/research.html

The study also noted that columbines can change from blue to red, then white to yellow. According to the researchers, the colour shift from red to white or yellow in columbines has already happened at least five times in North America.

So Why Do They Change?

There are several reasons why columbines change colours:

  • DNA mutation
  • Natural selection
  • Adaptive radiation
  • Hybridization
  • Changes in soil conditions

DNA Mutation

Based on the UC Santa Barbara findings, at least 34 genes produce different columbine flower colours. Because of the presence of various genes, there’s an increased likelihood that the colours will change simply due to gene mutation. It doesn’t happen because of creation of new genes, but just because of current gene mutation.

Natural Selection

In the studies and mentioned above, if most pollinators are hummingbirds, most of the columbine colours are red. However, when the population shifts and most of the pollinators become hawkmoths, there’s a potential for the colour to modify. The resulting blooms can be white or yellow.

Adaptive Mutation

Another concept explored in the study of the columbine colour changes is adaptive radiation, based on Charles Darwin’s Theory of Evolution, which assumes that living organisms change their structures to better adapt to the changes in their surroundings. For columbines, flowers develop new traits as a response to changes in their environment. In this case, the changes include the pollinators. 

Research shows that columbine flowers are tailored to the tongues of their pollinators, which shows an example of how they evolve based on their environment.

Hybridization

Columbine colour change can also be due to cross-breeding, when male and female parts are pollinated. The goal? Combining the positive attributes of two species, changing the physical characteristics, resulting in a better yield and disease resistance, among others. 

Hybridization can also occur non-deliberately – for example when we plant two columbine varieties near each other, this will often create colour changes from the original plants.

To prevent problem hybridization, especially with our native Eastern Red columbine (Aquilegia canadensis), the best thing you can do is plant the native species as far away from the cultivars as you – not foolproof but an important thing to consider. Or don’t have any cultivars on your property, but that doesn’t guarantee they will stay the same as pollinators move from garden to garden.

Changes in Soil Conditions

It’s common for columbine colours to shift because of slight changes in the soil’s pH, as well as the presence or absence of metal ions in the soil. A pH lower or higher than 6.0 to 6.5 can result in nutrients being unavailable, which in turn can affect colour.

Our beautiful native Eastern Red Columbine (Aquilegia canadensis)

Colour change in columbines is a fascinating phenomenon, as you can see from my “rabbit hole research”.

But here’s the bottom line – if you want to keep your native columbines from hybridizing with cultivars you have to keep them as far away from each other as possible. If you like the idea of them changing colours (for a variety of reasons) just sit back and enjoy!

MORE READING

Sudden evolutionary change in flowers (2022)

Biologists discover a gene critical to the development of columbines’ iconic spurs (2020)

‘A Hopeful Monster’ (2022)

Dramatic diversity of columbine flowers explained by a simple change in cell shape (2011)

Perennials, Weed Control

Where are the weeds?

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By Mary-Jane Pilgrim, Master Gardener

I was honoured to be part of the Lakefield Horticultural Society’s Garden Tour last summer, along with fellow MG Emma Murphy. It was a glorious day, and I loved the wide range of people who came to tour — each with different backgrounds and gardening styles.

The one question I fielded more than once is “where are the weeds”?

First of all, what’s a weed? To me, a weed is a plant that is growing where it is not wanted. My weeds could be your prized “Lubauchnia” (my hubby’s fabricated word for plants he doesn’t know the name of, which includes most plants).

Disclaimer: I didn’t inherit a bunch of the nasty weeds as there were no gardens at my house when we bought it 32 years ago. I do deal with the nasties at my gardening clients’ homes weekly, though!

For plants that are growing where they’re not wanted in my gardens, here’s what works for me:

  1. Don’t wait — smaller weeds are easier to get rid of than larger ones. This applies to spring and fall when we’re often not as diligent in getting outside. Sometimes it seems like a full grown weed can appear overnight during those seasons!
  2. Use mulch — I love my leaf mulch, and it seems to be very effective in suppressing weeds. A chipper makes short work of a pile of leaves. Mulch also conditions your soil and encourages earthworms and microorganisms, a win-win situation.
  3. It’s especially important to weed BEFORE the seed heads develop — you’ll save yourself a LOT of trouble getting them early in their life cycle.
  4. Cut back perennials after they’ve finished blooming, and check for the inevitable “weeds” underneath.
  5. Weed when the soil is moist, so that the maximum amount of root comes with the weed. Weeding in dry/hard soil results in small pieces of the root being left behind, which can usually regrow. I rarely weed without my trusty Lee Valley Root Knife — loosening the soil around the root before pulling.
  6. Watch newly planted perennials closely, especially natives. If they send out runners or if they are very proficient at casting seedlings, they get “shovel pruned” at my place. You can do you at your place.
  7. Lastly, “know your garden“. The more time you spend out there, the fewer undesirable plants there will be.

Simple knife-in then pulling works well for most regular weeds. However, some types such as japanese knotweed, lily of the valley, bindweed, cow vetch, DSV or creeping bellflower will require more diligence as their mother-roots are buried deep underground. Eradicating those weeds involves a lot of deep digging, soil sifting, and extreme diligence. There are actually support groups on Facebook for those truly invasive plants. May actually be easier to move!

Weeds that contain viable seeds should be “solarized” — left in a black plastic bag on the driveway for a couple weeks. The heat will fry the seeds. Dispose of the bag in the garbage. Don’t put seed heads attached into your composter.

There’s a new thought process that suggests that repetitively cutting difficult weeds at soil level is more effective than pulling them. It’s true that if it’s done often enough, those roots will eventually die for lack of nutrient supply from any top growth — however the weeds are usually much more persistent than the weeders! I read that cutting bindweed every 2 weeks will still take multiple years to make an impact. Sigh.

What are your tricks?