Decipher the moody fall weather to fast track everything you need to know about your property’s microclimate in Southern Ontario.

We’re currently stuck in the weird “I can’t make up my mind if I’m gross or lovely” that is autumn in Canada. But with what seems like a little of every season and every form of precipitation being tossed our way in just a month or so, this makes it the perfect time to figure out your property’s microclimates!

Why should you care about microclimates?

You should care because this will make you the master of your land! Ever wonder why some people just seem to know exactly what plant works where? Or they are able to pull off amazing feats growing things they shouldn’t be able to? This is the key.

What is a microclimate?

The climate of a very small or restricted area, especially when this differs from the climate of the surrounding area. i.e areas within your property.

When I’m asked what the first thing is that someone should do before designing a garden, I recommend sitting back and observing their space for a year. This response is rarely well received. Most do not have patience for this and want to jump right in. Beyond watching to see what plants and issues are already established in your land, you are watching for elements of microclimates.

This hack of utilizing the mood swings of autumn resolves the year long wait (mostly; it cannot predict what plants will sprout or what lifestyle your neighbours will lead, but it helps with determining microclimates)

Microclimate Relationships

In gardening, on a grand scale, there are hardiness zones. These are a defined geographic area that encompass a certain range of climatic conditions relevant to plant growth and survival. Examples of this are extreme temperatures, precipitation amounts and frost dates. These are the zones that plant tags refer to. Hardy down to zone 3 or a zone 6-9 something along those lines. But these zones are pretty broad.

Toronto falls into a zone 7. You may be wagging a finger at me saying "‘No! Toronto is a zone 6’ but, our climate is evolving and our region is changing. The Canadian Hardiness Zone map was updated in 2010 to reflect the accumulated data on our climatic conditions. There is also a USDA hardiness map which is different from the Canadian one. Short answer, Toronto is a USDA zone 5 .

From here you’ll have your local climates. If you look up your neighbourhood by postal code on the weather network and compare it against general “Toronto” you’ll get a pretty good idea of what I mean. At times my neighbourhood won’t get any rain, but 4km north of me at my in-laws they’ll be soaked. If you are part of any local gardening groups you will likely see the climate discrepancies whenever a storm is on it’s way. Reports will come in from some of damage, heavy rains and flooding, others will have a drizzle and some will only see the dark clouds.

Scaling it down further we have microclimates. To determine what our microclimates are we need to look at the following:

Sun
Wind
Precipitation
Canopies of trees
Fixed structures
Materials

Sun

It rises in the east and sets in the west, unless Daenerys gets her way (spoiler she didn’t). The sun causes many things but we are focusing on shadows and heat.

The suns positioning will create shadows from structures and trees. Seasons will also change the angle of the sun and therefore the intensity of it and the length of shadows. This is why gauging your space for an entire year is beneficial.

What do you need to note? Pop onto google earth or pull out the compass app on your phone, determine true north and begin to note the areas of your yard that the sun touches first and how long that area is in sun for. Check back each hour and note each time the area is in shade or sun. Even though you can google sunrise and sunset, these won’t apply to different pockets of your yard, unless you have a meadow with absolutely no structures or trees.

This works best on a bright sunny day. But what if it’s overcast? Beyond shadows we can use other visual indicators. When we get a light snow, watch where it melts first. It will usually be the west edges of your property, closest to the structures and the melt line will pull away from the structure as the day progresses.

By knowing how much sun each area gets we can select plants that prefer full sun, part sun or full shade accordingly.

Cheat sheet:

Morning sun, or east facing gets all the full sun light requirements but without the intense heat as building heat takes time. This means that a plant that like full sun, but doesn’t do well with intense heat (i.e. clematis) will favour an east facing location, where a tomato or pepper that thrives on intense heat and full sun will prefer a west facing garden plot.

Wind

Often overlooked by home gardeners, wind can be quite damaging, but it can also carry benefits such as encouraging pollination or making a hot day bearable. It will mound up snow in areas, relocate leaves from neighbours trees into your yard (or garbage), pelt one side of your home with rain leaving the other bone dry and it can cause your plants to dehydrate quicker then they, and you, may like.

What are we noting with the wind? Watch your windows next time it rains. The west windows and therefore the foundation will likely get plenty of moisture. The east side will likely have a zone that stays dry. How big is that zone?

Where do the leaves collect, do they tend to swirl or fly through certain areas? Do you require wind breaks or do you need to open an area up to encourage better air flow? By noting where the strongest winds are we can plan for plants that can handle the wind, that may act as a wind break or we can note ‘safe’ zones for storing more delicate or potted plants.

Knowing the direction of wind we can begin to plan for scented plants wafting into your home, rather than your neighbours, or protecting potted plants from the damaging winter winds. We can break the wind with structures or plants and account for supporting elements for more delicate plant matter.

Cheat Sheet:

In Toronto our prevailing winds come from the west to southwest in the summer and shift to northwest in the winter.
If you’ve ever commuted along bloor by bicycle you’ll be very familiar with this fact!

Precipitation

This might be the easiest item to note this time of the year as it seems its either raining or snowing or threatening to.

In the spring we often have so much water and we are not yet spending much time outdoors that it is challenging to determine where water pools unless it is a major problem, such as your entire yard flooding. In the summer, must of the water runs off into the sewer grates as the ground is too firm to absorb the short heavy rains. But as the ground begins to freeze in the fall it’s easier to see where water pools and collects without requiring a heavy downpour.

We are looking for: Natural low spots may need releveling or a selection of plants that can handle wet feet or land that needs regrading or other collection controls. As we noted in the wind category, certain zones around structures may be omitted when it rains and will need more drought tolerant plants or a better watering regime. Perhaps downspouts can be better utilized through redirection or collection or transformed into a rain garden.

This will point out the low spots in your garden that will be more susceptible to frost as well. Cold air settles into the lowest areas, if you want to extend your growing season these low zones should be avoided.

Tree canopies play a big role in moisture levels too. Why do we run under a tree when it starts to rain? To stay dry! Not only does the canopy shed rain or hold snow, preventing the area directly underneath from accessing the same amount of water as neighbouring zones, the trees are also thirsty. The area below the canopy is referred to as the drip line. Plants struggle under mature evergreens not due to the acidity of dropping needles but rather due to the lack of moisture left behind. This can be utilized in your favour too.

Tree+watering+cross-section.jpg — The area below the canopy is referred to as the drip line. This area will be impacted by changes in sun, wind, temperature adn moisture levels making it a critical item to observe.

If you want to avoid shoveling in the future, a line of broadly branched evergreens along the side of your driveway may be just what the garden designer ordered. The snow falls onto the branches and on it’s perch melts much faster then the snow on the ground. Less accumulates below the trees, drastically reducing your need to shovel!

Cheat Sheet

Low spots in your garden will be more susceptible to frost as well as pooling water.

Fixed Structures

These are buildings, garages or other outbuildings, fences, pergolas, sheds, pools etc. Each will impact the space around them. A pool may reflect light, a fence may block wind, a building will throw shadows, two buildings near each other may create a wind tunnel etc. These are items that generally cannot be changed but that may cause effects that we need to counter or that we can embrace.

We want to note the driplines, water deflection, shadows and wind effects of these items.

Examples of this in my space. The house faces east/west and at the front door I have the blueberry barrel. It overwinters well because it is shielded by the house from the prevailing winds yet gets to soak up the sunshine. The overhang at the front (east) coupled with the prevailing winds creates a ‘dry zone’. Our back porch sheds water and snow in sheets as it lacks gutters.

Cheat Sheet

Typically, changing fixed structures falls beyond project scope and the effects of these items must be considered for success.

Materials

Materials will amplify the natural elements around them. Brick retains heat and if it is the façade of your house, it may also store and release heat that escapes from your home as well. When noted, this can be a powerful tool to extend your growing capabilities. Dark materials will absorb more heat potentially scalding plants but also extending the capabilities if you are working with a heat loving plant, shiny materials can amplify sun and heat, hardscaping versus landscaping will impact both moisture and temperature.

This is another great opportunity to observe materials effects after a light snow or rain. What areas melt or dry up first? It will nearly always be a hardscaped zone. This can be pavers in a garden, or a driveway. Brick dries faster than wood etc.

I see the greatest impact of this in my front garden by the house. The brick reflects the heat it has stored all day and reflects it back into the garden. This area always thaws out first in the spring. My growing zone alongside the garage wall doesn’t thaw out as quickly as it’s siding but it still thaws faster then my neighbours beds just 10’ away even with all the same sun. Coupled with the black material of the grow bags I can get seeds into the earth earlier then many gardeners.

Areas with water problems, this could be your foundation having leaks, or large amounts of runoff along a driveway, may benefit from a change in materials. Opting for permeable options can not only aid in retaining water but the effects are felt more greatly beyond your property as surrounding areas (ravines and city infrastructure) no longer become overwhelmed by the excess moisture loss.

Mastering Microclimates in Southern Ontario