What is plant hardiness zone

A hardness zone is a geographically defined area in which climatic conditions’ a specific category of plant life is capable of growing, including its ability to survive the minimum temperatures of winter.

The Canadian hardiness map prepared in 2000 by Natural Resources and Agriculture Canada is divided into nine major hardiness zones: the harshest is 0 and the mildest is 8. Relatively few plants are suited to zone 0.  In addition to zones, also subzones (e.g., 4a or 4b, 5a or 5b) are noted in the map legend. These subzones are very important to  gardeners, as they pinpoint to their garden location.

The hardiness zones differ even within the greater Toronto area. For instance, Mississauga and Oakville fall into zone 6b, Brampton 6a and Etobicoke 7a. That means that in most part of Mississauga only plants that survive in the lowest temperatures -20.6 to -17.8 C, should be planted, while this threshold is lower in some parts of Toronto, including Etobicoke, where this range is -17.8 to -15.0 C, and in Brampton where the range is lower between -23.3 and -20.6 C.

Be aware of the hardiness zone in your area before you buy plants

Image result for hardiness zone mississaugaIf you are planning to buy a shrub, perennial or a tree, you need to make sure that this new plant will tolerate all-year-round temperatures in your area. To ensure that the new plant will survive and grow year after year you need to make sure that the hardiness zone in your area matches the hardness zone of the plant.

One would expect that local garden centres should only be selling plants that will thrive in local climate. This is not always the case. You need to remember that garden centres are in the business of selling their stock and what looks nice sells. That is why you need to do a bit of detective work before buying plants that look great in the nursery on a warm May day. Some plants may not survive over winter even though they look great in the nursery in the early spring at planting time. But what is hardiness zone? A hardness zone is a geographically defined area in which climatic conditions’ a specific category of plant life is capable of growing, including its ability to survive the minimum temperatures of winter.

Better garden centres list the hardiness zones as part of the description attached to the plants, but it is always prudent to double check the Canadian gardening reference books and nursery catalogues or just by searching the plant name online. Just make sure that you are using the Canadian reference sources as zones are differently defined for the U.S. and Canada. There are ten hardiness zones for the U.S. and only nine for Canada – that means that hardness zone 5 in the U.S. source refers to completely different climatic conditions that Canadian hardiness zone 5. Some of the plants you find in the nursery may be brought from the States and marked accordingly to the American system. All plants mentioned on our website refer to Canadian hardiness zones and each plant entry lists the range of zones where the plant is recommended.

In Canada, the Plant Hardiness Map produced most recently in 2000 by Natural Resources and Agriculture Canada scientists outlines nine different zones where various types of trees, shrubs and flowers will most likely survive. It is based on the average climatic conditions of each area, including minimum winter temperatures, length of the frost-free period, summer rainfall, maximum temperatures, snow cover, January rainfall and maximum wind speed. This updated plant hardiness map indicates that there have been changes in the hardiness zones consistent with the climate change. That may explain why some of the older plants in your garden do not perform well in the recent years. Also, one needs to be mindful that produced in 2000 hardiness map is already outdated. But this is still the best tool available to gardeners to help them to choose the best plants for their garden. The Canadian hardiness map is divided into nine major zones: the harshest is 0 and the mildest is 8. Relatively few plants are suited to zone 0. Subzones (e.g., 4a or 4b, 5a or 5b) are also noted in the map legend. These subzones are very important to Canadian gardeners, as they pinpoint to their garden location. You can also search for the hardiness zone by location, as well as use the interactive climate change forecasting tool to get a list of plants that will do well in your area in the future.

The hardiness zones differ even within the greater Toronto area, where Mississauga and Oakville fall into zone 6b (going up the scale from zone 6a in the late sixties when the first Canadian hardiness map was created), Brampton 6a (change from 5b) and Etobicoke 7a (change from 6a). That means that in most part of Mississauga only plants that survive in the lowest temperatures -20.6 to -17.8 C, should be planted, while this threshold is lower in some parts of Toronto, including Etobicoke, where this range is -17.8 to -15.0 C, and in Brampton where the range is lower between -23.3 and -20.6 C.

As every gardener learns, cold hardiness is only one factor in plant’s adaptation. Some significant local factors, such as micro-topography, amount of shelter and subtle local variations in snow cover, are too small to be captured on the hardiness map, yet they also influence the plant’s ability to survive. Other factors include the unique combinations of soil type, wind, rainfall, length and time of cold, humidity, summer temperatures, and temperatures in relation to humidity.

Another aspect of climate important in selecting plants is microclimate – the climate around your home that differs slightly from the general climate in your area. The northern side of your property, which is partially shaded most of the day by your house is cold microclimate. the southern part of your house, unless shaded by trees, receives hot sun almost all day, is a warm microclimate. At Landpol, when helping you plan your garden, we start with a site plan specific for your property. This helps us to identify the nuances in weather conditions and select the best plants for your garden.

Low maintenance annuals for lasting flower colour – part 1

Celosia plumose

Celosia plumose in a flowerbed

Celosias

If you are looking for lasting splashes of colour in your garden and a supply of fresh cut flowers to your table, annual flowering plants are your best friends. Of these, celosias, amaranths, gomphrenas and sunflowers are some of the hardiest on the market, that after the initial investment of care when planted, provide great returns throughout the season:

Very few flowers are as showy as celosia. Whether you plant the plumed type, which produces striking upright spires, or the crested type, which has a fascinating twisted form, you’ll enjoy the unusual red, pink, purple, gold or bi-colored flowers all summer and fall long as they typically bloom for up to 12 weeks in all the colors of a glowing sunset. When many celosia flower blooms are next to each other, they collectively resemble fire, thus their name Celosia, which means burning in Greek.

This is definitely a sun loving annual that grows between 1-8 feet tall and spread 6-18 inches wide. It requires watering until well established and can tolerate drought conditions later on.

You will love using celosia in bouquets, but you can also dry them easily. To dry these flowers, hang them upside down in a cool, dark, and dry place, for about two months. Celosia also makes a very showy, unusual display in borders and as edging. While the brilliant reds are by far the most popular color, Celosia, or Cockscomb, also come in yellow, orange, crimson, rose, and purple flowers.

Celosia is grown from very fine seeds. Celosia is usually grown as an annual; although this plant drops its seeds and given favourable conditions, it can seed on its own and take over an area larger than intended.

Amaranths

Amaranths produce tassels of dark red flowers

Amaranths

Amaranths are showy and exotic accent plants, ideal for beds and borders. They are also great in bouquets and in dried flower arrangements. At maturity, amaranth flowers cascade to the ground from tall, erect branching stems in breathtaking tassels of the darkest red or green.

The plant is large and bushy, growing about 3 to 4 feet high. Although amaranth is primarily cultivated as an annual ornamental plant, many of its species are grown as edible leaf vegetables or cereals.

Considered a native plant of Peru, this hardy plant is now grown around the world, including Ontario. Amaranth prefers partly shady to full sunlight conditions and a high elevation, but it can grow at almost any elevation in temperate climates. The soil type is not overly important, though it should have a PH between 6 and 7. For the most vibrant flowers it is best that the soil is not too rich, as this soil type encourages growth. Amarath can also survive in low-water conditions once the plants have been established.

Gomprena Fireworks

Gomprena Fireworks

Gomprena

If you’re looking for a tough plant that will keep on blooming despite the heat of the summer, gomphrena is a perfect choice for that. This native to Panama and Guatemala plant, also known as globe flower or globe amaranth, produces dozens of showy, globe-shaped lavender, purple, pink, red, magenta, blue, orange and white flowers that blooms from early summer to frost. The additional colours are brought to your garden by a variety of butterflies this sun-loving plant is sure to attract.

Gomphrena can reach about 25cm to 45cm in height. The flowers look a lot like clover about 1 inch in diameter, and they seem to last forever and have a straw-like texture. As such, they are highly valued for dried flower or cut flower arrangements.

Once established, gomphrena is actually maintenance-free. But the plant needs to establish itself first, so it’s best to give your gomphrena plant some extra pampering initially. Even though gomphrena can tolerate hot and dry weather, you still need to provide sufficient water to saturate the root zone. You have to be careful when watering gomphrena during the roots establishment – the plant does not like wet soil, so even in this initial stage do not water the plant again until the soil dries after the previous watering. Also, be sure to plant gomphrena in full sun. The plant will tolerate partial shade, but in full sun will produces better flowers.

sunflowers
Van Gogh in the garden

Sunflowers

American natives, sunflowers, have been grown in the Americas for centuries. They have been cultivated both, for decorative beauty and as a valuable food source when harvested for seed.

These annual plants have big, daisy-like flower faces of bright yellow (occasionally red) petals, and brown centers that ripen into heavy heads filled with seeds. Tall and sturdy, the plants have creeping or tuberous roots and large, bristly leaves. Some sunflowers grow to over 16 feet in height, however, most of the newly developed varieties on the market today are small plants suitable for small spaces and containers that are used mainly as cut flowers.

Sunflowers are remarkably tough and easy to grow as long as the soil is not wet. Most are heat- and drought-tolerant. They make excellent cut flowers and are sure to attract to bees and birds.

Landscaping Mississauga Gardens – Sumac

Staghorn sumac will bring an interesting display of colours in the late summer and fall

Staghorn sumac will bring an interesting display of colours in the late summer and fall

Large shrubs for dry soil – sumac

Depending upon whom you ask, sumac (sometimes spelled, “sumach”) is considered either a small tree or a tall shrub. Regardless in what category the plant is put, it certainly outperforms the largest trees with its fall colourful foliage. Dense stands of sumac trees covering a slope next to some Ontario highways in a sea of red, are some of the best fall foliage spectacles we witness each year. Despite their beauty sumacs recently became less popular. This is due to the confusion resulting from the fact that apart from the delightful and harmless sumacs, there also exists in the wild a poisonous version of the species that can cause a severe skin irritation when touched. Poison sumac, however, is in a distinct minority amongst the sumacs. The remaining sumac trees and shrubs produce no poison, but provide spectacular autumn color.

Additionally, it is easy to distinguish poison sumacs from their non-poison sumac relatives in the fall, when the berries have ripened to maturity. The poisonous plants have white berries in the fall, and the berries hang down. Non-poison sumacs bear red berries and their berries grow upright. In addition, poison sumac plants grow almost exclusively in swamps, whereas non-poison sumac plants prefer precisely the opposite habitat — soils that are well-drained and many are drought- tolerant. To avoid any confusion it is best to buy sumacs from nurseries.

One of the most popular sumacs in the GTA area is staghorn sumac, a tough plant that can be grown in dry areas of the garden. It is a relatively tall, tree-like variety that can reach up to 25 feet in height. Staghorn derives its name from the hairy texture of its branches, reminiscent of the velvety feel of deer antlers. The smooth sumac tree (Rhus glabra) is another common variety; it attains a height of about 10 feet. Both provide striking fall foliage.

As mentioned at the outset, the fall foliage they provide is unsurpassed. Nor is their autumn color display limited to their leaves, for the tuft atop the plant that holds sumac’s berries is red and fluffy, increasing the plant’s visual appeal. An added bonus is the fact that this seed-tuft remains on the sumac trees all winter, attracting colorful wild birds, whose presence greatly enhances the color and variety of winter scenery. Increasingly, homeowners begin to understand the importance of achieving four seasons of visual interest on the landscape and sumac is perfect for that as adequate winter scenery is perhaps the most difficult to achieve, since vegetation is more robust in the other three seasons.

Sumac in winter

Sumac in winter

Sumac seeds are an important source of bird food, precisely because they do stay on the plant long enough to be part of your winter scenery. This makes them an excellent emergency food for birds throughout the winter and beyond. I have witnessed bluebirds, black-capped chickadees and robins feeding on sumac seeds throughout the whole winter and into early spring today.

Landscaping Mississauga Gardens – Best trees for dry conditions: Honey locust, Turkish hazel & Russian olive

honey locust
honey-locust is a drought resistant shade tree

Honey locust

A great choice if you want a hassle-free, attractive, fast-growing (18”+ annually) ornamental tree that won’t shade out your lawn and landscaping as it has small leaflets that produce a filtered shade.

This native to central North America, deciduous tree requires very little maintenance once planted and established. In fact, it performs best if not fertilized or watered, since optimal growth conditions in the summer and rapid growth may increases susceptibility to winter dieback of some of the new branches.

Honey locust can reach a height of 20–30 m (66–100 ft). Its leaves are bright green in spring and turn yellow in the fall. The leaves are small and in the fall they simply disappear into the lawn and decompose, without any need for raking. The strongly scented cream-colored flowers appear in clusters by late spring. The name of this tree derives from the sweet taste of its fruit, flat legume pulp that matures in early autumn. The pulp is used for food by Native American people, and it can also be fermented to make beer. The long pods, which eventually dry and ripen to brown or maroon, make a striking visual statement against the winter snow.

This ornamental tree is your best choice in dry areas, where few other trees can survive and prosper and it also tolerates urban conditions, compacted soil, road salt, alkaline soil, heat and drought. The fast growth rate and tolerance of poor site conditions make it valued in areas where shade is wanted quickly.

 

Fast growing drought-tolerant shady tree

Fast growing drought-tolerant shady tree

Turkish hazel

 

 

Another excellent small tree choice for drier sites.  It is drought-tolerant, but it also does well in wet conditions. This a tree for all challenging landscaping condition. It grows up to 40’ tall and has a broad, distinctive and refined pyramidal shape with interesting corky bark, and dark green foliage throughout the season. The crinkled round leaves turn yellow in October.  The foliage is dense and the tree provides a nice shade in summer right from the beginning.

 

 

Russian olive can be grown as a small tree or a shrub

Russian olive can be grown as a small tree or a shrub

Russian olive

Russian olive, commonly called silver berry, oleaster or Persian olive is a native to the western and central Asia, an area stretching from southern Russia and Kazakhstan to Turkey and Iran, which is becoming very popular in Ontario as introduced species.

Russian olive can be grown either as a large thorny shrub if you trim it regularly or it can grow to the size of a small tree up to 5 metres in height. This drought-resistant ornamental plant is a very attractive addition to any garden with its dense covering of silvery to rusty leaves and highly scented flowers that appear in early spring and are followed by clusters of small cherry-like orange-red fruit covered in silvery scales. The fruits are edible, and in Iran, the dried power of Russian olive fruits mixed with milk is used to treat rheumatoid arthritis and joint pains.

Russian olive needs to be planted with caution. Because it thrives in very poor soil conditions, has low seeding mortality and matures in a few years it often outcompetes the other plants and can become invasive.

Please see our previous entries for landscaping in dry soil conditions and the best evergreens to plant in these conditions.

Landscaping Mississauga Gardens – composting

If the soil tests described in our last two blog entries show that you need to improve the soil, you can do so in two ways; by adding the missing chemical components or composting.

The best way to build a better soil is to work in lots of organic matter that can solve all sorts of soil problems, such as poor drainage, lack of earthworms, extreme pH levels, or low nutrients.  The best source of organic matter is compost pile, which allows you to recycle leaves, grass clippings, plant debris, and household food waste into a nutrient rich soil conditioner.  Follow the steps below to learn how to make a compost pile:

composting1

1.Build a compost pile from alternating lawyers of “wet” material (green plant matter, fruit and vegetable peels, coffee grounds) and dry plant debris.

 

 

composting2

2. Sprinkle wet lawyers with wood ashes (for potassium and to lower pH) or lime (to raise pH) and livestock manure, or blood meal (a slaughterhouse by-product), or garden soil.

 

 

composting3

3. Spray the compost pile with water until it is moist as a squeezed out sponge; later moisten the pile whenever it gets dried out.

 

 

composting4

4. Turn the compost once a week, moving material from the outer edges of the pile into the center; the compost is ready to use once it is dark brown and crumby.

 

 

Repeat every year. Adding compost to your soil every year will keep it in good shape for growing plants.

Landscaping Mississauga – knowing the soil type

Plants grow in a variety of soils from Yukon tundra to Wasaga beaches; most individual plants, however, do well only in particular types of soil.  Thus, a crucial first step in designing a low maintenance garden is to evaluate your soil and the kinds of plants that grow best in it.

Sand and clay represent two extreme soil conditions. Clay soil consists of tiny particles packed together so tightly that water has difficulty seeping through.  Dense and heavy clay tends to block the spread of roots and may ultimately suffocate them; yet, the clay soil is usually loaded with nutrients because they have little opportunity to wash away.

Sandy soil contains large, loose-fitting particles that constantly shift. It has many air pocket for water to drain through and ample room for roots to spread.

Although you can find plants suitable for clay or sandy soil, you can greatly expand your selection by improving the soil with organic matter.  Your goal should be to create soil that drains within an hour after heavy rain, crumbles fairly easily in your hand, and is full of nutrients.  You can also buy a soil-testing kit from your local garden centre or hardware store and test your soil for acidity (pH scale) and key nutrients, such as nitrogen (for leaf and stem growth), phosphorus ( for root development and seeds formation) and potassium (that enhances plants vigor and resistance to diseases.  The majority of plants in the Greater Toronto Area will flourish in soils with pH ranging between 6 and 7, which is mildly acid to neutral.

Follow the steps below to test your soil:

soil type testing step 1.Step 1:

To get a representative sample of soil, mix trowefuls of soil from different parts of the garden together and put a small amount of soil in the kit’s test tube.

 

soil type 2Step 2:

Add the required amount of indicator fluid to the collected soil; gently shake the tube, and wait for the content to settle.

 

soil type 3Step 3:

Compare the tube to the test kit’s colour chart.  The more expensive your kit is the more accurate information on your soil conditions will you be able to derive.

 

soil type 4Step 4:

If your soil’s pH is too low, add lime to raise the level; on the other hand, to lower teh pH level, work powdered sulfur or wood ashes into the soil.  See the next week’s blog entry for details how to improve the soil condition.

Landscaping Mississauga gardens – Lawn weeds control

crabgrassBefore we say anything else, it is important to note that it is difficult if not impossible for weeds to invade dense, healthy turf and so they are seldom a serious problem on well-constructed and properly maintained lawns.  Weeds can be troublesome on neglected areas or lawns on poor soil. Although hand pulling is practical when weeds are sparse, high weed populations require chemical treatment. If weeds continue to invade after proper chemical treatment, some other facet of maintenance is at fault and steps should be taken to remedy the failing.

Chemicals used to control weeds in established lawns are called herbicides and are applied as preemergence or postemergence treatments.  Preeemergence herbicides are applied before weed seeds germinate and as the the seeds or seedlings begin growth they absorb enough chemical to kill them. Permanent lawn grasses are relatively unaffected. Postemergence herbicides are applied after weed seed germination when the weeds are in active growth, and such formulations do not greatly affect affect lawn grasses. Some chemicals are selective in that they kill only broad-leaved plants but not grass.  Others are nonselective and kill both weeds and lawn grasses.

  • Correctly identifying the weed and then selecting a proper chemical for its control are crucial.
  • Timing is also important. For example, dandelions may be controlled in midspring and late summer in Ontario because they are growing actively and are very susceptible to selective chemicals.
  • Choose a clear day with little or no air movement and temperatures of 15-25 C degrees. Such weather permits rapid absorption and uptake of the chemical with little chance of drift or spread beyond the treated area.
  • Do not apply herbicides during the excessive heat.
  • Follow exactly the directions on the package regarding dosages.
  • Keep all containers out of the reach of children and pets.
  • Wash your hands thoroughly after using the chemicals.
  • Do not use the same sprayer for different pesticides because it is virtually impossible to rinse out all traces of toxic herbicides; use separate sprayers and label them clearly.