A Focus on Foundation Planting

Despite the fact that almost every homeowner wants foundation planting, few people understand what its true role is. This misunderstanding can lead to some common foundation planting mistakes that a wise landscape designer will avoid. 

What is Foundation Planting?

The term "foundation planting" refers to the plants that grow around your house, or, more accurately, around your house’s foundation. 

To understand foundation planting, it helps to imagine the outside of a typical house. In most cases, a small portion of a house's foundation will be visible from the exterior. 

Foundation planting hides this small portion of the foundation and replaces that view with something of greater ornamental value, often a shrub, perennial, or annual plant.

The Biggest Foundation Planting Mistake

The biggest mistake people make when creating foundation plantings is choosing plants that are simply too large. This occurs because people often fail to anticipate the mature size of a plant before planting it. 

Although many plants look quite small when they first go into the ground, some will quickly expand wider than their growing space allows. In foundation planting, this means the plant may begin to engulf your home, going far beyond its original purpose of blocking just a few inches of exposed foundation. 

The well-known phrase, “right plant, right place”, is an adage you should follow when creating any type of planting, but it’s especially true regarding foundation planting plans.

How Large Plants Become a Problem in Foundation Planting 

Using a large plant species in your foundation planting plan can quickly present problems in multiple ways. Below are some brief summaries of the problems that may happen in these cases. 

Ornamental Issues

Regardless of the more functional factors, which we'll explain shortly, placing a large plant right next to your foundation rarely enhances the ornamental value of your property. 

More often, large plants that are too close to your house will quickly become overgrown and detract from the visual appeal of your home. This scenario makes your plants look out of place in relation to your house and the rest of your landscape design. 

Thoughtful design from the start ensures that your foundation planting will be attractive and proportional to the rest of your property. 

Damage to the Exterior of Your Home

In some cases, plants that touch the outside of your home can cause damage. The exact type of damage can vary and will likely be minimal at first. 

That said, a quality inspector will quickly note any branches that contact the exterior of your house since they can negatively impact your home's structural integrity as well as your utilities. 

Large shrubs and trees are often responsible for this type of damage, but the same is true for vines. In fact, some of the most popular vines attach to surfaces using adhesive pads, also known as holdfasts. This adhesive makes it very difficult to remove the vine without damaging the surface it grows on. 

Put simply, allowing plants to touch your house indefinitely only increases the odds that damage will occur. Using the right strategy when making a foundation planting plan makes it easy to avoid this problem. 

Foundation Problems

Overgrown foundation plants are generally unattractive and can damage the above-ground portions of your house. Still, what's most concerning is what can happen under the soil's surface. 

Although this can vary by species, a plant's root system often expands across a larger distance than the above-ground portions of the plant. When a plant grows close to your house and develops a deep or vigorous root system, little prevents its roots from growing into your foundation. Those roots can form cracks that diminish the foundation's structural strength and may allow water to seep inside. 

This problem is especially prevalent for any foundation that includes mortar, such as brick or cinderblock foundations, as the presence of mortar makes it easier for roots to work their way into the wall. That said, even if your foundation does not include mortar, certain roots can still create cracks in the foundation wall, although it will likely take longer than if mortar were present. 

To be clear, roots do not account for the majority of foundation problems. Additionally, growing a large plant near your foundation does not guarantee its roots will cause foundation issues. Instead, it just makes that outcome more likely than it needs to be. Keeping this issue in mind allows you to develop a foundation planting plan that will benefit your home rather than damaging it. 

Create Foundation Planting Plans the Right Way

The best way to avoid the problems outlined above is to never plant large shrubs, trees, or vines that use holdfasts in close proximity to your foundation. 

What’s even more effective is actively choosing plants that will thrive in your foundation planting bed and have root systems that are unlikely to interfere with the structural integrity of your home. 

Of course, regardless of your project, you should select plants that grow well in your region, are non-invasive, and are suited to the sun, water, and soil conditions in your intended growing space. 

After fulfilling those requirements, you’ll want to consider two main factors. 

Evaluate the Root Systems of Your Foundation Plants

This may seem complex, but you don’t need to have any special knowledge to evaluate a plant’s root system. Instead, an online search will reveal what you need to know. 

Enter the name of a plant into the online search bar, followed by the words "root system". Adding other terms like "foundation damage" can narrow your search and help find the information you need. 

Entering those search terms will reveal the general tendencies of the plant's root system. Broadly speaking, plants that have a shallow root system pose less of a threat to underground structures. Conversely, if a plant's root system is "deep", "aggressive", "invasive", or "vigorous", it has a much higher potential to damage your foundation. 

Invasive Root System vs. Invasive Species

Here's a quick note to clear up some potential confusion: if a plant has an invasive root system, that does not necessarily mean that the species itself is invasive to that area. 

For example, Acer saccharinum, commonly known as silver maple, is native to the eastern part of the US, meaning it is not an invasive species there. Still, this plant does have an “invasive” root system, meaning the roots usually spread aggressively, whether or not they grow in a location where the species itself is invasive. 

Use Proper Spacing for Foundation Plantings

Another essential element of foundation planting is spacing. This is where the mature size of a plant is important. Again, it’s easy to find the mature size of a plant online, and, in many cases, when you purchase a plant, it will come with a tag that indicates how large it will grow. 

The listed size of a plant’s mature width, or spread, typically represents the diameter of the plant at maturity. For planting, you’ll want to focus on the radius dimension by dividing the diameter in two. Let’s use another example to illustrate this point. 

Syringa vulgaris, better known as lilac, can have a 12-foot spread at maturity. Dividing that number in half gives you a six-foot radius. This means that from the center of a lilac shrub, it’s safe to assume the plant could expand six feet in any direction. As such, it’s best not to plant this species within six feet of your foundation. 

Proper spacing is most important for large shrubs and trees, especially when they are known to have aggressive root systems. On the other hand, many perennial plants and annuals are less likely to have root systems that can damage your foundation. The same can be true for many shrubs, including small shrubs and dwarf varieties. 

What’s the Value of Foundation Planting?

When planning foundation plantings, it’s crucial to avoid some common pitfalls. After that, it’s time to focus on how a foundation planting can dramatically enhance the beauty of your home. 

Foundation planting can be attractive in its own right, but it can also add considerably to the curb appeal of your home. Likewise, a landscape design is not fully complete without considering how foundation planting can complement your house and the design as a whole.

Want a Foundation Planting Plan for Your Home?

I’m a landscape designer serving property owners in Western Massachusetts and Northern Connecticut. If you’re interested in foundation plantings or any other type of landscape design project, I encourage you to contact me at any time.