September 2024 In The Garden

This Autumn, paint your garden in fall colors with Zone 3 Shrubs and Trees.

September in Saskatchewan is a beautiful time of year. There are warm, sunny, cool days that bring beautiful fall leaf colors to our deciduous trees and shrubs. There are so many areas of Saskatchewan that provide us with outstanding fall color – one of them being Valley Road near Saskatoon that takes you to Floral Acres Garden Centre. Valley Road is only part of the South Saskatchewan River Valley fall tour that features beautiful trees and landsapes.

Some of our fall seasons are more colorful than others. There are many reasons for this and leaf color variation depends on a combination of many factors. Weather, tree/shrub health, genetics, drought, amount of seasonal rainfall and early or late frosts all contribute to fall leaf color. A cold snap can kill the leaves immediately with the colors going from green to brown overnight. If the weather is too warm going into winter, tree leaves may just hang on the branches until they die. Too much nitrogen fertilizer applied after August 15 forces a tree to focus on growing instead of toughening up and getting ready for winter.

A leaf changing color is a multi-step process. Leaves are green due to a pigment in the leaf called chlorophyll. Chlorophyll absorbs light from the sun and creates food for the plant. There are other pigments in leaves that do not show themselves until the chlorophyll fades away in autumn. The shorter days of autumn cause the chlorophyll to slowly die and the tree/shrub stops growing. The other pigments in the leaves will begin to show in shades of red, yellow, and orange. During this process, abscission cells form at the base of the leaf’s stem cutting off the nutrients received from the tree.  Eventually the leaves will drop off the tree. If the temperatures stay warm into winter, the tree never starts making abscission cells. The leaves will be droopy but stay attached to the branches. Some trees, such as oaks, are prone to keeping their leaves into winter.

The pigments that give some tree and shrubs their fall color are called carotenoids and anthocyanins. We also know them as beneficial antioxidants in the food we eat.  Carotenoids are responsible for orange and yellow leaf colors and are also found in green, orange and yellow vegetables and orange and red fruits. Anthocyanins form in some tree leaves and produce purple, blue, red and black fall colors. They are also found in red, blue and purple fruits and vegetables.

Every great Zone 3 landscape design incorporates deciduous trees and shrubs of outstanding fall color. They are especially welcome in large perennial beds as a backdrop for summer and fall blooming perennials.  They often have beautiful blooms of their own and berries that feed pollinating insects and birds.  Some have a distinctive leaf color all season long.

To follow are just a few of the outstanding fall color deciduous trees and shrubs you can be adding to your Zone 3 landscape and enjoy for years to come. 

Saskatoons – (Amelanchier Canadensis) - Saskatoon shrubs/trees have it all – small white flowers in spring, followed by delicious berries (just ask the birds!) and beautiful orange, red and pink fall leaf color.  Be aware that some varieties will sucker.

One such beautiful Saskatoon is Amelanchier x grandiflora ‘Autumn Brilliance’.  It is a small tree with gorgeous orange – red autumn leaf color.

My favorite small tree or shrub for fall color is the Amur Maple.  (Acer ginnala) The cultivar called ‘Flame’ is a particularly vibrant red leaf color in fall. For fiery fall color and intense red seeds in the late summer and fall, plant the Hot Wings Tatarian Maple.

Other larger maple trees that have outstanding fall color are Autumn Blaze (oranges), Rocky Mountain Glow Big Tooth (orange and red) and Silver Cloud (yellow in fall).

Mountain Ashes ( Sorbus) are outstanding all season trees; particularly in fall. Two of the many varieties of Mountain Ash known for their orange and red leaf colors are the Luxor Pyramidal Mountain Ash and the Russian Mountain Ash. Both have clusters of orange – red berries that persist on the trees into fall and provide food for birds. These two are particularly suitable for smaller city gardens.

Birch, Linden and Quaking Aspen all have striking bright yellow fall color and are better suited to parks or large city lots, acreages and farms.

Bailey Select Schubert Cherry – (Prunus virginiana) - The new leaves are green, slowly maturing into a deep purple and are deep red in fall.

Ohio Buckeye (Aesculus glabra) – A large Zone 3 tree with striking orangey – red fall color. The leaves are palmately compound with panicles of yellow flowers in summer. All parts of an Ohio Buckeye tree are poisonous to humans and pets. This also applies to the large nuts that form on the tree in late summer and fall.

Shrubs

When one thinks of shrubs with beautiful fall color, I think we often forget about the Double Flowering Plum.  (Prunus triloba ‘Multiplex’. ) Not only does it have bright pink double flowers in spring before the leaves emerge but is a real stunner in fall with orange, golden, and red leaves with tinges of pink.

Ninebarks - ( Physocarpus  opulifolius) -  Ninebarks of any variety or cultivar are tough, showy shrubs that feature exceptional spring, summer and fall color. Their naturally peeling stem bark also adds to their fall and winter appeal.  A few varieties of note are Amber Jubilee, Royal Jubilee, Tiny Wine and Tiny Wine Gold, Red Robe, Dart’s Gold, Panther, Summer Wine and Sweet Cherry Tea. I especially like Centre Glow and Coppertina Ninebark for their unique foliage color(s) that are so attractive all season long.

Burning Bush (Euonymus alatus / Euonymus nanus) are best known for their fall color.  However they are Zone 4 shrubs. Keep the following varieties in mind if you have a protected sunny spot in your garden. Dwarf Turkestan (brick red), Dwarf Winged (luminous red in fall), Fireball (bright red), Chicago Fire (florescent red), and Little Moses (crimson red).

If you are in need of a tough shrub for a difficult area (wet or dry) or a shrub that will prevent soil erosion on a hillside consider Aronia or Black Chokeberry. (Aronia melanocarpa) It has outstanding red fall color with dark purple edible berries. Do be aware that this shrub suckers so do not use it in a flower bed.  

Peking Cotoneaster are typically used as a hedging shrub but can also be used as a single specimen in your garden as well. They are easy to control by pruning in summer and deliver beautiful red/orange leaf color in fall. 

Other notable shrubs with great fall color are:  Spireas (yellows, oranges, reds and purples), Barberry, and Currants (yellow). Bailey Compact (Viburnum trilobum) and Dwarf European (Viburnum opulus) both turn a stunning shade of red in the fall. This is also true of the Highbush Cranberry (Viburnum trilobum) and its cultivar ‘Redwing’

Dogwoods

I find dogwood shrubs are hit and miss with fall color.  They are better known for their deep red or yellow branches that stand out in winter. Dogwoods with decent fall color are Red Osier (rose, gold and green), Arctic Fire (burgundy), Neon Burst ( blends of yellow, red, purple and orange), Golden Variegated (purple, red ), and Variegated Silver Charm ( bright yellow).