Category Archives: Advice

Advice, Houseplants, Information, Pets, Toxicity

Toxic Indoor Plants and Your Pets: A Guide

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by Emma Murphy, Master Gardener

While I like to think of myself as a decent outdoor gardener, the same cannot be said of my indoor houseplant expertise.

However, I have worked hard at it over the years and we’ve had some lovely Clivia, various cactus, some Pothos, a Norfolk Island pine, and a goldfish plant (Columnea gloriosa) in my office at various times.

My pre-2018 houseplants (my Mum’s cat Cleo showed no interest at all)

This was pre-2018, when my indoor kitties had no interest in my houseplants, and no nibbles were had.

That all changed when these two arrived in October 2018 – meet Lulu and Roxy.

Meet Lulu and Roxy – our tuxedo and ginger and white female cats (respectively).

While I love both of them, Lulu’s favourite activities are digging in the dirt and chewing on plants. Roxy just likes to rub up against them, knock them over and then maybe have a nibble.

While indoor plants can add beauty and life to your home, it’s essential to be aware of their potential toxicity to our furry friends. Certain plants can be harmful or even fatal to pets, especially cats and dogs. Understanding which plants are safe and which to avoid is crucial for ensuring a pet-friendly environment.

Many common indoor plants are toxic to pets, such as Pothos (Devil’s Ivy), which causes vomiting and oral irritation in cats and dogs, lilies (which are particularly dangerous for cats) and sago palms, which are extremely toxic, especially to dogs, causing severe liver damage. The Ontario SPCA has a list of the 17 most poisonous plants, but it’s not an exhaustive list.

If you suspect your pet has ingested a toxic plant, it’s best to consult a veterinarian immediately. Look for signs such as difficulty breathing, vomiting, diarrhea, or lethargy. It’s always better to be safe than sorry.

Reliable Resources on Plant Toxicity for Pet Owners

Here are some reputable websites offering advice on pet safety and plant toxicity:

The American Society for the Prevention of Cruelty to Animals’ (ASPCA’s) Animal Poison Control Center
A comprehensive and excellent searchable list of toxic and non-toxic plants.

Pet Poison Helpline Canada
Assistance for pet owners who suspect poisoning, including plant toxicity resources (there is a cost).

PetMD
Plants poisonous to cats
Plants poisonous to dogs
Detailed information on animal health and safety, including plant toxicity.

So What Plants Can I Have In My House?

If you’re looking to enhance your home with pet-friendly plants, here are a few options for you to consider. Personally, I find the palms, ferns and spider plants still tough to have in our house because I think our cats will gravitate to anything that is grass-like.

Unfortunately if your cat or dog is a habitual nibbler, you might be better off without houseplants altogether. We love our kitties more than we love our houseplants. For now I’ll just stick to my Phalaenopsis orchids and my various seasonal cactus and focus my gardening efforts on the outside of our house.

Spider Plant (Chlorophytum comosum)
African Violet  (Saintpaulia ionantha)
Prayer Plant (Maranta leuconeura)
Orchids (Phalaenopsis spp.)
Easter, Christmas or Thanksgiving Cactus (Schlumbergera or Rhipsalidopsi spp.)
Bromeliads (Bromeliaceae)      
Bamboo Palm (Chamaedorea seifrizii)
Sword/Boston Fern (Nephrolepis exaltata)
Nerve Plant (Fittonia)   
Ponytail Palm (Beaucarnea recurvata)
Hoya (Hoya carnosa)   
Gerber Daisy (Gerbera jamesonii)         
Areca Palm (Dypsis lutescens)
Calathea (Calathea spp.)
Lady Palm (Rhapis excelsa)
Lucky Bamboo (Dracaena sanderiana)
Friendship Plant (Pilea involucrata)

Also have a look at this Laidback Gardener post.

Advice, Bulbs, Dreams, Websites

The Magic of Transformation

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By Marilyn Homewood, Master Gardener

As we draw closer to the Autumn Equinox, my thoughts dwell more frequently on the topic of fall planted bulbs.  For me, they evoke a powerful sense of anticipation similar to what I felt as a child when the Eaton’s and Simpson’s Christmas catalogues arrived.  The suspense and delayed gratification that both provide is beyond words.  A seemingly lifeless bulb has the potential to create a stunning spring display of bloom after the harshness of the Canadian winter!

Participating in this ritual is easy with not too many things to looks for.  When purchasing in person, look for the largest bulb for the type you can find (good quality tulips are typically 12+ cm in circumference, daffodils may be larger or smaller depending on variety).  The larger the bulb, the more blooms that you will have in the spring.  Bulb size is probably most important in tulips as not all varieties size up well once planted.  Major bulbs known to perennialize (narcissus, allium for example) will size up.  I once bought some Leucojum (summer snowflake) bulbs late in the year locally knowing nothing about them, planted them and had to wait 2 years for bloom. They were worth the wait. Last year, I dug some of them up and the bulbs were at least three times the size of what I planted.  Bulbs should also be plump and firm with no mold or black spots.

Local nurseries are a good source of bulbs as are some of the larger outlets with nurseries. 

More frequently, bulbs are purchased online.  Online suppliers will usually be able to provide bulb size and the bulbs they ship should be healthy.  Ask for a recommendation from someone in your horticultural society (there is always at least one bulb nut in every club). Vesey’s and Brecks are long time reputable suppliers of bulbs.  Also, have a look at the local flower farmer’s webpage.  It is quite common for them to retail some of the varieties they have ordered for themselves.  In this area Dahlia May Flower Farm and Antonio Valente Flowers both have attractive offerings each fall.  With online orders of course, there is the additional cost of the shipping.

A British Columbia company, “Wildwood Express” offers packaged bulbs for sale that are sourced from a reputable importer in BC.  They often have last minute sales that are hard to resist and of course end of year sales late in the season.  Bulbs can be planted very late into the season (if the ground can still be worked, and YOU are hardy enough).

Of course, there are often good local sales.  Not for profit organizations often sell bulbs as a fundraiser.  Consider these sales, both to buy some magic and to support a good cause.  In our area the Port Hope Garden Club and the Peterborough Master Gardeners have bulbs for sale. Consult the PMG website for details on their sale and for Port Hope, drop me an email through this website.

Some of us have succumbed to temptation long ago.  For this year, I ordered around 1700 bulbs last spring (less than last year!), have bought some from the club sale in Port Hope and still broke down and ordered a few fancy new narcissus from a flower farmer. 

Advice, Garden Design, Greenhouses, Herbs, Planting, Vegetable Gardening

Cold Frames – A Mini Greenhouse in Your Garden

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by Brandi McNeely, Master Gardener in Training

I’m sipping my coffee on the deck, overlooking my vegetable garden. Everything shows signs of fall. The onions and garlic have been harvested. The green beans are finished for the season and are ready for the compost pile. The zucchini and summer squash are suffering from powdery mildew, and the tomatoes are carrying the last few fruits of the season. Although summer is ending, the fall gardening season is just beginning – and I have a secret weapon: a cold frame.

Why Cold Frames Work

Several leafy green vegetables can survive and even thrive in cooler temperatures. Kale, lettuce, Swiss chard, and spinach produce sugars that lower the freezing point of water in their cells, protecting them from damaging ice crystals. These crops tend to bolt in the heat of summer but thrive in the crisp days of fall. Still, even hardy plants will eventually succumb to our harsh Canadian winters.

That’s where a cold frame comes in – you can significantly extend your growing season with one. Imagine brushing snow off your cold frame in November to harvest fresh kale for a salad!

Cold frame basics (Source: “Large Cold Frame” by Ofer El-Hashahar, CC BY-SA 2.0)

What Is a Cold Frame?

A cold frame is a low, bottomless structure with a transparent lid that protects plants from wind and cold. The lid lets sunlight in, while the insulated base traps heat and creates a microclimate that can run several degrees warmer than the surrounding air. Ventilation is key – open the lid on sunny days to prevent overheating and ensure proper airflow.

Cold frames come in various styles depending on budget, materials, and space.

Types of Cold Frames

Traditional Cold Frame
Built from wood with an angled, hinged top – this could use glass, polycarbonate, or heavy plastic. They can be permanent or portable and built with reclaimed or new materials. An old window makes a perfect lid.

Straw Bale Cold Frame
 Stack straw bales to form a frame and cover with windows or plastic sheeting. Straw provides insulation and can be reused or composted in spring.

Hot Bed
 A sunken bed filled with compostable material such as horse manure, straw, or poultry bedding, covered with soil and topped with a cold frame. As the material decomposes, it generates heat, warming the soil below.

Traditional cold frame using wood and an old window (Source:“cold-frame-in-winter” by The Art of Doing Stuff, CC BY-NC-ND 2.0)
Straw bale cold frame (Source: “Quick coldframe, straw bales and old windows” by Irene Kightley, CC BY-SA 2.0 – Flickr)

Need a visual? Watch DIY Cold Frame • Easy How‑to Tutorial with Niki Jabbour to see an easy cold frame build using recycled materials—great for Canadian gardeners. Or for a classic approach, check out How to Build a Cold Frame | This Old House, a clear demo using a salvaged window lid.

Tips for Success

  • Timing is everything: Sow spinach, kale, or lettuce in late August or early September to harvest well into late fall – or even December, depending on snow cover.
  • Ventilation matters: Even on sunny October days, closed frames can overheat. Keep lids open when needed.
  • Spring bonus: In March or April, use your cold frame to start early crops like lettuce or radishes, or to harden off seedlings before planting.

The Quiet Magic of Cold Frames

No matter which style you choose, a cold frame is a valuable addition to any garden. It helps you garden later into the season and gives you a head start in spring.

With one simple structure, you don’t have to say goodbye to your garden when frost arrives. Picture a crisp November morning—brushing snow from the lid and harvesting fresh spinach for breakfast. That’s the quiet magic a cold frame brings to your backyard.

Banner photo “Large Cold Frame With Props” by Ofer El-Hashahar, CC BY-SA 2.0

Advice, Climate Change, Compost, Drought, Native Plants, Perennials, Water

Searching for Rain – Rethinking the Future of our Gardens

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By Emma Murphy, Master Gardener

Heat. Humidity. Thunderstorms but no real rain. Dry soil.

cracked soil and dry leaves

What I wouldn’t give for a week of solid, consistent rain in our gardens. After the March ice storm, followed by a cool, wet spring and high water conditions until May, Mother Nature turned the water faucet off and we haven’t had solid rain for what feels like months.

I rarely have to water our established perennial gardens, which are a mix of native and non-native plants, but this month has been the exception.

So it’s time to think about the future. What can we do so our gardens survive (and thrive) during future dry or drought conditions?

Maintain Healthy Soils

Good soil is the foundation for good plant growth. Anything you can add to your soil like compost or other organic matter will make it easier for roots to penetrate deeper, creating more expansive root systems that can seek out water and nutrients. Check out Master Gardener Sharleen Pratt’s previous blog.

The result? Healthier, more drought-resistant plants. Good soils are better able to absorb surface water runoff, minimize erosion, and access nutrients and sediments.

hands holding soil with small plant seedling

Think About Future Plant Selection

Evaluate your plants for their resistance to dry conditions or drought; look for new plants (hey, who doesn’t want more plants?) that are identified as drought-tolerant or drought-resistant. Group plants according to how much water they need. Ask your local garden centre or nursery staff which plants they recommend.

Consider incorporating more native plants, which generally adapt better, have lower water demands, and fewer pest problems, plus of course the many benefits they provide to our pollinators and wildlife. In Our Nature has some great ideas.

bumble bee on native purple asters
Bumblebee on native asters

Use Mulch

Mulch reduces evaporation, moderates soil temperature, and inhibits weed growth. It is estimated that three quarters of the rain falling on bare soil is lost to plants through evaporation and runoff.

Use compost, wood chips, bark nuggets, shredded bark mulch, shredded leaves, or any other organic material to cover the surface of the soil at least 5 cm in thickness. More info and a deeper dive here.

shredded bark mulch
Shredded wood mulch

Water Well

Long, deep watering encourages roots to go deep down in the soil to where it is moist and a lot cooler. Water less frequently but for longer periods, so water reaches deep into soil. Good thorough watering promotes healthier plants.

Water only when necessary. Most plants will normally wilt in hot sun and then recover when watered. Also, a dry surface is not always a sign of water need. The surface generally dries out first and is not a true indicator of what is going on down deep near the plant root. Make use of a hand trowel or your fingers to check for moisture.

Weed Management

Weeds will compete with your plants for moisture and nutrients. Keep your gardens and areas beneath trees and shrubs weed free. Once the weeds are eradicated, apply mulch.

Consider Alternate Water Collection and Distribution Methods

Water harvesting is a great way to use water from your home’s roof and direct it onto the landscape, where the soil becomes your “holding tank.” The best example is using a rain barrel – we have various rain barrels and tanks in our garden and they are a great investment.

You can also practice ‘passive’ water harvesting by creating depressions that fill with water from the roof runoff or formal rain gardens, both of which help with stormwater runoff issues. Peterborough Greenup Rain Program

Investigate use of soaker hoses or other irrigation techniques using timers, which keep water on the soil and reduce losses by evaporation. Adjust watering frequency and amounts based on season, temperature, and amount of rainfall. Overhead watering uses more water and encourages fungal diseases.

rainwater barrel beside house
Rainwater barrel and water diverters – check out Rainbarrel.ca for location of sales

Practice Water Conservation Everywhere

Not just in your gardens. Water is our most valuable resource. Learn how to reduce water use throughout your house and gardens. The Simple Guide to Water Conservation and Make Every Raindrop Count.

water droplets on leaf
Advice, Information, Light, Sun Gardening

When Plants + Sun = Trouble

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By Mary-Jane Pilgrim, Master Gardener

Have you ever gotten a weird red rash or burn after spending time outside? If you were pulling weeds or brushing up against certain plants, you might’ve had something called phytophotodermatitis. It sounds scary, but it’s really just a fancy name for a skin reaction that happens when plant juice meets sunshine.

Here’s how it works: some plants (like wild parsnip, giant hogweed, gas plant (Dictamnus), citrus fruits, dill, parsley, celery, fennel and even carrots) have natural chemicals in them called furanocoumarins. When these chemicals get on your skin and are then exposed to sunlight — especially strong summer sun — your skin can react. It might not hurt at first, but after a day or so you might notice red patches, streaks, or even blistering. It often looks like a burn or a splash mark.

People sometimes mistake it for poison ivy, but phytophotodermatitis is different. Poison ivy causes allergic contact dermatitis due to the urushiol oil in its sap. Phytophotodermatitis is not an allergic reaction, and it doesn’t usually itch. It’s more like a sunburn that was triggered by a plant.

Sometimes the blistering can be quite severe.

The good news? It usually goes away on its own in a few weeks, though it can leave behind darker patches of skin for a while. Severe burns may require medical treatment, including potential debridement (removal of damaged tissue) and skin grafts. Protect the affected area from sunlight for an extended period to prevent further irritation.

To avoid it, wear gloves when gardening, wash your skin after handling plants outdoors, and try to avoid sun exposure right after. And if you’re chopping limes for drinks on a sunny patio — wash your hands and arms!

It’s a sneaky kind of sunburn (or worse!), but a little knowledge goes a long way in preventing it.

Advice, Bees & Pollinators, Garden Design, Perennials

Using Broken Branches as Plant Supports

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By Marjorie Vendrig, Master Gardener in Training

Gardeners and municipal services in Peterborough and areas hit by the ice-storm are busy picking up the broken branches and limbs and using them for city compost and recycling programs.

Another use for some of this wood might be found in our own gardens, repurposing them for use as stakes and supports. The timing for the ice storm was perfect; the broken branches are young and supple and without leaves so they can be bent easily and shaped to suit needs. Small branches can be bent or twisted to create low supports for perennials or annuals that become leggy as the season progresses or to prop up flowers as the plants bloom. Heavier and longer branches can be used as poles for teepees in vegetable gardens for beans and peas or for climbers such as sweet peas and clematis.

This Photo by Unknown Author is licensed under CC BY-SA-NC

British and European gardeners have historically avoided plastic and metal as garden supports, instead ‘pea sticks’ are the norm. Pea sticks are usually coppiced hazel branches, but any young pliable wood will work.  Birch, lilac, red dogwood, along with oak and maple twigs and branches are at the top of the list, willow is popular as well but it tends to root and sprout – an advantage or disadvantage depending on where and how it is used. In some cases, a branch with lots of twigs and small growth is the best choice as the plant will grow under and over the branches.  In in other instances the small twigs might appear messy and a visual distraction.  When selecting your sticks, it’s important to take into account your garden aesthetic – are you going for the scrambling abundance of a country garden, or the formal structure of a classic retreat? Sarah Raven, a well-known British gardener has taken things a step further and made an effort to use only native wood when creating plant supports for her vegetable gardens.

In the ice-storm clean up, I collected a few branches for use as supports. My sweet pea seedlings are ready to plant outside, they’ll be perfect growing up and around the broken branch of a very special cornus Kousa, a sad loss from the storm. The long stem on the bottom is cut off at a sharp angle to be pushed into the soft spring soil as deep as possible.  The spread of the small twigs and branches will be close to the ground within easy reach of the seedlings planted around the base where they will quickly grow up and through the twigs and branches. Clematis would also do well on this structure and it’s likely strong enough to withstand several seasons. The popular annual mandevilla vine is another good choice as a climber. All add vertical interest to garden design.

My scrambling cotoneaster became too leggy and suffered a lot this winter. It’s now had a hard prune and I am using the cut offs to create small branch cages around some perennials. Yarrow, nepeta, tradescantia, and phlox are good candidates for this simple approach. Four or more long branches, each about 3’ long and with a similar diameter were chosen.  The new spring growth from the cutoffs will soon turn brown so I snipped off the new

growth and twigs, then pushed the thick end of each branch into the soil about 6” from its base, repeating this at the other three corners, to create four points of a box around the plant. The upright ends of the branches are then bent into hoops towards the opposite corner and wound around one another to create a hoop. More support is provided at the front where the plant flops towards the sun. I’ve made the hoop about 2/3 the final height of the plant and should be able to increase the height a bit by untwisting the ends a bit, if necessary.  At the end of the season, I’ll leave the hoops in place if they are sturdy enough for another season or add them to the compost pile.

My technique is very much that of a beginner; I expect I’ll refine things with more practice. Even still, the natural wood hoops are more appealing than  a plastic pole with string around it. In formal gardens in the UK, I have seen cages of plant supports that are works of art in themselves. It all takes time and patience.

References

Sarah Raven, Using Native Wood Structures (Retrieved May 7, 2025)

Types of Woodland Management, (Retrieved May 7, 2025)

Longfield Gardens, DIY Plant Supports, (Retrieved May 9, 2025)

Gardens Illustrated, How to Make your Own Plant Supports and Protection That Are Easy, Cheap and Full of Charm, (Retrieved May 8, 2025)

Advice, Bees & Pollinators, Compost, Information, Shrubs & Trees

Deadwood in the Garden

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By Lois Scott, Master Gardener

It was my sister that put the notion in my head that I would like a snag in my garden and the recent ice storm provided the opportunity.  A standard Serviceberry cultivar was too broken to save but it left a reasonable and safe trunk for my smallish garden.  It also left some small logs to tuck under shrubs.

Dead wood provides positive impacts to biodiversity as many beneficial species are on the search for dead wood.  ‘Some of these species include cavity nesting birds and mammals, beetles, fungi and other plants and beneficial insects.  Decaying wood positively impacts soil keeping your garden sustainable for years to come’.  https://ecologicaldesignlab.ca/site/uploads/2024/12/04_good-garden-practices.pdf 

Ecologically speaking a snag refers to a standing dead or dying tree, often missing a top or most of the smaller branches.  A snag is also known as a den, cavity or wildlife tree.  The following link (Ottawa Field Naturalists’ Club) provides an excellent description of the importance of wildlife trees to wildlife.  They provide food, safe cavity nesting sites and platforms, roosting and denning sites, hunting perches, display stations and foraging sites for a wide variety of species.  https://ofnc.ca/conservation-how-to/the-importance-of-snags-and-downed-logs-to-wildlife. 

Safety first so have a certified arborist advise you on the appropriateness of a potential tree.

Photo:  Top of the snag in author’s garden

Dead wood that is lying in your garden is an excellent addition.  It will be quickly colonized by natural decay fungi known as saprophytic fungi, my new word of the day!  These fungi help recycle the carbon and nutrients stored in woody tissue back into the garden soil which benefits your plants.  A small pile of logs can support many different insects and provide shelter for small mammals, reptiles and amphibians and shelter for over-wintering and hibernating wildlife.  https://www.rhs.org.uk/wildlife/dead-wood-compost-heap-habitats  This may not make everybody’s heart sing but I like the idea.

Photo:  A favourite chunk of wood in author’s garden

The small snag I now have may be more ecologically beneficial as a log on the ground but I have some ideas for it.  I plan on providing some support on it for a vine, maybe a Apios americana (American Groundnut).  There will probably be a small birdhouse attached.  The new logs have joined other decaying wood that I use as garden edging and garden decoration. 

One man’s garbage is another man’s treasure!

Advice, Annuals, Disease, Forcing Plants, Planting, Seeds

Horticultural Hiccups

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By Marilyn Homewood, Master Gardener

At times, these blogs seem a little like an Instagram Post. We show our successes in the hope of inspiring you and in turn, provide something of value to you.  However, that can be a little intimidating to less experienced gardeners. Today, I thought I would showcase some of my 2025 failures (so far).

Lisianthus germination (or not)

Lisianthus

This one is a heartbreaker! In January, I had almost 100% germination of my lisianthus. A couple weeks after germination, they looked like this.

What happened? After reading somewhere that cinnamon prevents growth of algae, this grower overzealously applied cinnamon (I had purchased a large bottle at Costco). The covering of spice initially smothered some of the young seedlings.  I then tried to rectify the situation by wetting the plants (cinnamon is extremely hard to wet). 

The overwatering led to a slow decline, killing more seedlings by rotting the roots.  All was not lost however, I potted up the remaining seedlings into other containers and they have been growing on.  Hopefully they will catch up in size over the long growing season.

As Julia Child was fond of saying “everything in moderation….including moderation”

Bells of Ireland

Bells of Ireland

These seeds are notoriously hard to germinate.  They need to be stratified by exposing the seed to cool, moist conditions to help to break dormancy.  The seed is placed on moistened paper towel that is then folded and placed into a Ziploc bag.  Then placed into the fridge for a couple of weeks. After that, remove to a warm place (I use a heat mat). 

After a period of time, the seeds are checked for germination and placed on the surface of prepared soil.  The daily checking goes on for a few days and hopefully you get enough germinated seeds.  This years’ results speak for themselves.  Hard to know what went wrong but it may be the seed source.  My usual source (that does germination testing on every lot) was out of seed so I purchased from another.

Dahlia Splitting

Last fall I used a new method of splitting dahlias that saved time.  I use flagging tape to identify the plants dug up and the tubers being stored.  As the dahlia afternoon wore on, some of the tubers seem to get mixed up and the quality of the labeling seemed to decrease. This tuber might be a Ferncliff Copper and then again, it might not be. Note to self – Take a little more care with the labelling.

Forcing Tulips in Bulb Crates

Seemed like a great idea last October. I do not have a cool place that does not freeze so I opted to chill my bulbs in the refrigerator. Bulbs in paper bags went into the crispers of the fridge for over 14 weeks.  During that time ethylene producing produce could not be kept in the fridge as ethylene can negatively affect bulbs and their bloom. 

After the chill period, bulbs were planted in soiless mix in bulb crates and kept dark for a couple of weeks to develop roots.  The crates were then placed in a sunroom to grow.

I got a total of 20 lovely tulips from about 150 bulbs.  Other bulbs did grow leaves but produced no flowers, some did not grow at all.  When I removed the bulbs from the soil, I did notice reduced root growth on many of the bulbs. This may be from inadequate chilling. 

The crate method is clearly more successful when you can plant the bulbs up in the fall and place in a very cool spot that does not freeze (or a cooler like the flower farmer).  Bulb crates full of soil is messy in the house even if they are on tarps!

Despite these hiccups, I have a roomful of healthy seedlings and large landscape beds awaiting more garden gaffes. 

In the words of Janet Kilburn Phillips “There are no gardening mistakes, only experiments.”

Advice, Climate Change, Information, Planting, Tools

What Zone Am I?

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by Christine Freeburn, Master Gardener

Having just come back from places where tropicals are growing wildly and flowers are blooming, I wanted to discuss growing zones and the importance of knowing your zone for overwintering plant success of perennials, trees and shrubs.

Plant hardiness zones can be a confusing subject. In Canada, we generally use the USDA (United States Department of Agriculture) system because it is the one we often see on labels of the potted plants we purchase at greenhouses and big box stores.

Source: PlantMaps – https://www.plantmaps.com/interactive-ontario-plant-zone-hardiness-map.php

The USDA system was designed in 1960, updated in 2012 and again in 2023. These hardiness zones are determined as “geographic areas that have an average annual minimum temperature of a certain degree.”  No other factors are taken into consideration. There are 13 zones with zone 1 being the coldest and zone 13, the warmest.

Natural Resources Canada has their own system which uses factors that include the number of frost free days, amount of rainfall, snowfall, and wind as well as mean temperatures in the coldest and warmest month. There are 9 zones. Interestingly, Ontario has 7 of these zones.

To complicate things further, there are also ‘a’ and ‘b’ zones. Zone 3a is colder than Zone 3b.

When you look at the government of Canada site, you will see zone dates from 1961-1990 and then an update of 1981-2010. In most cases, zones have moved by at least half a zone. In 2024, Natural Resources Canada was to release an updated version. At press time, I did not find an update.

Plants are described as being hardy to a zone #. If a plant is listed as zone 6, it will survive in Zone 6 or higher. If you live in Zone 4, and try to grow and overwinter a Zone 6 perennial, you will probably not be successful. You are better off to look at lower numbered zones from what your area suggests, to be sure a plant is going to survive and be robust.

Reading plant labels and buying plants that are zone appropriate will help you to have more overwintering success. You will notice on most labels the zone is the USDA system. The label may say “perennial” but look at the zone. A plant can be a perennial…..but only in Florida (Zone 8 or higher).

Other factors for overwintering success include snow cover, wind, and humidity. Snow cover is a great insulator, wind can cause windburn, humidity will help plants stay hydrated.

With climate change happening, our Peterborough area has changed from 5a to 5b which means our average annual minimal temperature has moved from -26.1C to -23.3C.

Below are some towns and cities and their current zones:

  • Bancroft – Zone 4a ( interesting to note, this zone did not change in the update)
  • Haliburton – Zone 4b
  • Port Hope – Zone 6a
  • Pickering – Zone 6a
  • Hamilton – Zone 6b
  • Thunder Bay – Zone 3b
  • Lakefield, Lindsay, Norwood, and Ennismore are all the same as Peterborough’s – Zone 5b

Things to Remember

  • Canadian and American systems are not the same. For instance, Zone 5 under the USDA system should be considered Zone 6 in Canada
  • You can stretch the zones, if you have a micro climate or spot protected from wind, good snow cover and a milder winter

So depending on your gardening confidence, you can stick to Zone 3 or 4 perennials for zonal success or be adventurous and try that beautiful Zone 6 perennial.  Just remember to read your labels and check your zones.

Resources

Hardiness Zone Maps

Canada Plant Hardiness Maps

5th National Climate Assessment and an Update on the Plant Hardiness Zone Map – The Garden Professors

Plant hardiness zone maps are not created equal

The Differences Between US and Canadian Plant Hardiness Zones

Advice, Pruning, Shrubs & Trees

Getting Pumped About Pruning

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By Carol Anderson, Master Gardener

What else is there to do in February, other than shovel … so why not begin planning your spring gardening clean-up? In my last blog, I shared with you my invasive ground cover plight and promised to update you in the early summer with my progress on eradicating and controlling the many species on my property. But I didn’t share with you the whole story – that in my excitement over my new home, I failed to look at the overall state on my gardens … more specifically my shrubs. It would appear that the previous homeowner planted somewhere between 20-30 shrubs about 17 years ago … and then forgot about them! So in addition to my “ground cover grievances”, I also have some “bothersome bushes”! Let me share with you my plan-of-attack to address overgrown flowering shrubs in my garden using a few examples that you will recognize.

Although pruning supports the growth of healthy and robust plants, it is one of the most inconsistent and often poorly executed garden techniques. Pruning is not only essential to maintaining plant health, but also an essential practice used to improve the quality of the plant (e.g. flowers or yield), “train” plants (shape and structure), and control their size. Perhaps the reason that pruning is avoided by many gardeners is because proper pruning takes careful planning and execution; knowing your plants growth patterns and life cycle will determine pruning time and technique to be used. The general rule of thumb, as you likely know, is that if the shrub blooms in the spring (e.g. common lilac, bridal wreath spirea, some ninebark), then most likely the flowers bloom from buds formed on last years’ growth. Therefore, pruning after flowering enables new growth to become established in preparation for flowering the following year. In contrast, most summer blooming shrubs (e.g. hydrangea, hibiscus) will flower on “new growth”, therefore they require a late winter/early spring prune to stimulate new growth for flowering in the same year. 

In general, your garden pruning is undertaken as follows

Step 1.

Create a pruning plan based on each shrub’s needs and growth habits.  Include timing and any specific needs of the shrub and any notes you made from last year’s observations.

Step 2,

Sanitation pruning (removing dead, dying and broken branches) should be carried out on all shrubs in the spring and fall and as needed throughout the growing season, regardless of the flowering time.

Step 3.

Pruning approach. The approach will depend upon the objective. Thinning (removing older branches to their point of origin) is used to improve vigour by stimulating growth throughout the plant, as well as air and light penetration. This is most often done when the shrub is overcrowded. Heading back (pruning back to a lateral branch or node with an outward facing bud lower on the stem) is used to improve overall vigour and bushiness (by diverting energy to the new growth) and to enhance flowering.

However, given that most of my flowering shrubs are overgrown and will likely not produce as they should, I need to utilize additional (more drastic) pruning techniques as follows:

Group 1. Very overgrown, dense mat of old growth, minimal flowering and damaged branches/potential for disease.

e.g. Common ninebark (Physocarpus opulifolius), Bridal wreath spirea (Spirea prunifoloia), and Common Lilac (Syringa vulgaris)

Reserved for only the most neglected and problematic shrubs … Extensive Rejuvenation (or Renewal) Pruning!  This technique requires pruning the entire shrub down to 6-10” from the ground in the Spring and then pruning out ½ of the new growth mid-summer and heading back the other ½ of the new growth to encourage bushiness. Not all flowering Shrubs can tolerate this. If these shrubs show signs of disease, they will be removed.

Group 2. Flowers evident, branches spindly/lack vigour/bushiness.

e.g. Panicle hydrangea (Hydrangea paniculata)

Gradual Rejuvenation (renewal) Pruning. This method is intended to truly rejuvenate a plant, while maintaining its’ overall appearance, making it more attractive during the renewal process. The technique requires 3 years, removing 1/3 of the oldest growth each year.

Group 3. Shrub has foliage but limited flowering and stunted growth.

e.g. Rose of Sharon (Hibiscus syriacus)

Although a Rose of Sharon does not usually need regular pruning (unless to manage shape or size), it would appear that heading back would be beneficial to stimulate vigour, new growth and budding. It is likely that this shrub may also need some specific fertilizer in Spring to stimulate growth and bud formation or soil amendments to acidify the soil.

As always, stay tuned and in my next blog I will update everyone on my invasive groundcover and overgrown shrub approaches (what worked, what didn’t and what next)!!!