As fall approaches, the first acorns begin to drop from the oak trees. Before long, squirrels arrive and get busy. If you watch them, you probably won't see them eating many acorns right away. They're far too busy gathering and carrying them off to build up their winter stores. Some of these hidden acorns will eventually be found and eaten, while others will be forgotten… giving them a chance to germinate and, one day, grow into majestic oak trees.
And perhaps, as you read this, you're tempted to follow the squirrels' lead… Planting an oak is a great idea! But which oak should you choose? They may look fairly similar at first glance, but their hardiness and preferences for soil and moisture can vary considerably. Before planting an oak that may one day become one of the largest trees on your property, it's important to choose a species suited to the space you have available and the growing conditions on your site. So, Red Oak, White Oak, Bur Oak, Swamp White Oak… which one should you choose? Here's how to find the right one among the different oak species.
Key Factors to Consider When Choosing an Oak
Space and Sun Exposure
Oak species certainly have some characteristics in common. Most are large, wide-spreading trees that require plenty of room to reach their full potential. Pin Oak is among the smaller species at maturity, reaching an estimated height of about 20 m (65 ft). Oaks also generally grow best in sunny locations.
Make sure you have a large space with full sun. If your site cannot provide enough sunlight or room for the tree to develop, another species may be a better choice. From there, you'll need to consider your region's hardiness zone and the soil conditions on your property.
Your Region's Hardiness Zone
To grow an oak, you need to be located in Zone 2 or warmer. In Zone 2, only one oak is hardy enough to withstand the climate: Bur Oak. Exceptionally cold-hardy, it is the best choice for regions with the harshest winters.
Starting in Zone 3, Red Oak becomes another option. In Zone 4, the selection expands considerably to include Swamp White Oak, White Oak, Pin Oak, and Black Oak. Finally, English Oak, hardy to Zone 5, is better suited to regions with milder winters.
Photo: White Oak leaves. This species is hardy from Zone 4.
Your hardiness zone is therefore a simple way to rule out species that aren't suited to your region. Once you've narrowed down your options, the next step is to determine which oaks are best suited to the soil, drainage, and available space on your property.
Soil Moisture and Drainage
Most oaks can adapt to a range of soil textures, including clay, loam, and sandy soils. When choosing between species, it is often more useful to focus on soil moisture and drainage.
Does your property become very dry in summer? Does the soil remain moist without becoming waterlogged? Does water collect after heavy rain or during the spring snowmelt? Some species, such as Red Oak, White Oak, and Black Oak, prefer well-drained soils, while Swamp White Oak and Pin Oak are much better adapted to moist soils and sites with imperfect drainage. Bur Oak, meanwhile, stands out for its ability to adapt to a particularly wide range of growing conditions.
Good to Know About Pin Oak
Pin Oak has one additional requirement to consider: it prefers acidic soils and does not tolerate alkaline soils well. When the soil pH is too high, iron becomes less available to the tree, which can lead to iron chlorosis. A common sign is yellowing leaves while the veins remain greener. In calcareous or alkaline soils, it is therefore best to choose another oak species.
Which Oaks Grow the Fastest?
Oaks are generally known for their slow to moderate growth. These are long-lived trees that establish themselves for the long term and develop gradually over the years. Some species, however, stand out for their faster growth, including Red Oak and Pin Oak. Under favourable conditions, they are among the faster-growing oaks and can be good choices when you want a tree to reach a substantial size somewhat sooner.
Photo: Red Oak leaves in fall. Red Oak can grow approximately 30–60 cm (12–24 in) per year.
Keep in mind, however, that the growth rate given for a species represents its potential under favourable growing conditions. A Red Oak planted in suitable soil, with plenty of sunlight and adequate water during establishment, will be much more likely to reach its growth potential than a tree planted under challenging conditions.
Choosing the right site is therefore essential. Soil and drainage suited to the species, adequate sunlight, enough space for root development, and a reliable water supply during the first few years will help the tree establish successfully and reach its optimal growth rate. Conversely, soil conditions that are poorly suited to the species can significantly slow its growth.
Native Oaks of Eastern Canada
A Choice That Supports Biodiversity
Oaks are among the most important trees for biodiversity. In North America, the genus Quercus ranks first among the plant genera studied for its importance in networks linking host plants and Lepidoptera.
This ecological importance is largely the result of relationships that have developed over time between trees and the organisms that share their natural range. A native oak is therefore part of a complex network of interactions with insects and, indirectly, with the birds and other animals that feed on them.
Four oak species are native to Quebec: Red Oak, Bur Oak, White Oak, and Swamp White Oak. Swamp White Oak is of special interest because it is considered a rare native species with a precarious status in the province.
Distribution of Native Oak Species by Province
| Species | ON | QC | NB | NS | PE |
|---|---|---|---|---|---|
| Red Oak | ✓ | ✓ | ✓ | ✓ | ✓ |
| Bur Oak | ✓ | ✓ | ✓ | ||
| White Oak | ✓ | ✓ | |||
| Swamp White Oak | ✓ | ✓ | |||
| Pin Oak | ✓ | ||||
| Black Oak | ✓ | ||||
| English Oak |
ON: Ontario | QC: Quebec | NB: New Brunswick | NS: Nova Scotia | PE: Prince Edward Island. Grey cells indicate that the species is not native to that province. Data from Canadensys.
How to Identify Different Native Oaks
If curiosity has you wondering about an oak you come across, the following resource can help you identify oak species found in Quebec.
More generally, you can start with a few key characteristics:
1. Look at the leaf lobes: are they pointed or rounded?
Pointed lobes
- Red Oak
- Pin Oak
- Black Oak
Rounded lobes
- White Oak
- Swamp White Oak
- Bur Oak
2. Next, look for a few distinctive characteristics.
Among oaks with rounded leaf lobes, leaves with silvery-white undersides point toward Swamp White Oak, while very large, irregularly shaped leaves combined with acorns with a fringed cup are characteristic of Bur Oak.
Among oaks with pointed leaf lobes, the very deep sinuses of Pin Oak leaves generally make it fairly easy to distinguish from Red Oak.
FAQ About Choosing and Planting Oaks
Do Oak Trees Grow Quickly? How Long Does It Take for an Oak to Become a Large Tree?
Most oaks have a slow to moderate growth rate. Among the species in our selection, Red Oak and Pin Oak are among the faster-growing options when conditions are favourable. Even so, it takes many years for a young plant to develop into a large tree. Growth depends greatly on soil conditions, drainage, sunlight, and water availability, especially during the first few years.
Can You Plant an Oak Tree Near a House?
It's important to allow enough room for the tree's mature size. Most oaks develop into large trees with broad crowns. They should therefore be planted a suitable distance from foundations, overhead wires, and other structures so they have enough room to develop naturally without requiring extensive pruning.
Which Oak Is Best for Wet Soil?
Pin Oak and Swamp White Oak are among the best choices for moist soils and sites with imperfect drainage. Pin Oak is especially well suited to moist conditions, but it prefers acidic soil and can develop iron chlorosis in alkaline or calcareous soils.
Which Oak Should I Choose for a Cold Climate?
Bur Oak is the hardiest species in our selection and can be grown starting in Zone 2. In Zone 3, Red Oak becomes another option. The other species in our collection generally require Zone 4 or 5.
Do Deer Browse Oak Trees?
Yes. Young oak trees can be browsed by deer, which may feed on young shoots, buds, and leaves. Young trunks can also be damaged when bucks rub their antlers against them. In areas with high deer populations, protecting young trees during their first few years is recommended.
Noble Oaks!
Majestic in stature and remarkably long-lived, oaks hold a special place in our natural and cultural heritage. An oak planted today may one day grow large enough to provide shade for generations who come long after the person who planted it. Oaks therefore play an important role in both our landscapes and our ecosystems. For decades—and often centuries—successive generations of living organisms can find food and shelter in and around an oak, including fungi, lichens, insects, birds, and a wide variety of small and large mammals.
Does the squirrel know all this? Does it realize that by absent-mindedly scattering and forgetting some of its harvest, it is helping secure the future of these trees and the habitat they will provide for generations to come? Perhaps not. Either way, we can be grateful for the important legacy it leaves behind.
Article written by Suzanne Simard, Horticultural Writer and Certified Horticultural Technologist, and Audrey Rondeau, Biologist, M.Env., Director of Production and Development at Pépinière Vert Forêt.
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