I’ve been considering getting blueberry plants for a while now and I wanted to know if they’re invasive in the garden, or if I can plant them pretty much anywhere. Here’s what I found.
According to Oregon State University, blueberry plants are not invasive as the majority of their roots are less than 1 foot deep and are found within 8-12 inches of the plant’s base. Because of their shallow roots, they’re highly unlikely to cause damage to surrounding structures and the environment.
So, while blueberry bushes are not invasive, are there times when their roots can pose problems? Let’s take a closer look.
How Long Do Blueberry Roots Grow?
Generally, blueberry roots grow up to 8-12 inches long, which is not very far from the base, or crown of the plant. The main job of these roots is to obtain water and nutrients for the plant, but some finer roots work with mycorrhizal fungi for extra benefits.
In general, blueberry roots do not extend very far from the plant. In most soils, 50% to 60% of the roots are located in the top foot of soil and are within 8 to 12 inches from the crown.
Professor Bernadine Strik, NWREC Berry Crops Research Leader
The roots of blueberry plants are responsible for gathering primary resources from the surrounding environment, such as:
- Nutrients
- Water
- Oxygen
Ideally, the best soil for blueberry bushes is one that’s loose, rich, moist, and has an acidic pH of 4.5-5.5 (source). Soil that meets all three of these qualities will promote the best root growth.
The reason why blueberry roots grow shallow roots is that the topsoil is where much of the nutrients and water is located. Because of this, some blueberry bushes are poorly anchored from the wind and large herbivores.
However, blueberry roots can have their growth limited by:
- Extremely cold weather
- Compact soil
- Lack of water
- Lack of nutrients
Soil compaction is common in suburban areas or construction sites and will give blueberry bushes a hard time growing their roots.
And this issue is made worse with heavy clay soils.
Compact clay soil not only makes it difficult for the plant’s roots to grow but creates poor drainage and high alkalinity, leading to poor nutrient uptake. Some acidity in the soil is needed to dissolve the solid nutrients and make them accessible to the tree’s finer roots.
Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.
Donald Bickelhaupt, SUNY College of Environmental Science and Forestry
This is why the ideal soil for blueberry bushes is loose, well-draining, and has an acidic pH.
If you’d like to learn more about planting in or amending clay soil, check out my recent post: Can Fruit Trees Grow in Clay Soil (& How Do You Plant Them)?.
Keep in mind that most plants (including blueberries) start growing their roots from April to November, with two big surges in between. The first surge in root growth is in the spring—when the plant needs many nutrients to develop fruit. And the second surge is in the summer—when the plant is gathering nutrients to prepare for winter dormancy.
Generally, blueberry bushes start growing their roots once the soil temperature reaches 55ºF or higher.
If all of these ideal growing conditions are met, blueberry plant roots can grow up to 1 foot long. But just how deep can they grow?
How Deep Do Blueberry Roots Grow?
Blueberry plants have shallow roots, with 50% to 60% of their roots found in the first 1 foot of soil. While many factors contribute to the exact depth of blueberry roots, the main ones are water, nutrients, and space. Blueberry roots are unlikely to damage pipes or foundations but should be placed away to be safe.
The deepest root is the taproot, which has the main function of establishing a foundation for the rest of the roots. The taproot is one of the first roots to grow and can assess the nutrient and water potency of the soil. It commonly grows to a depth of around 1-2 feet. If the taproot is damaged or broken, it’s unlikely to grow back and the rest of the bush can become stunted.
Blueberry roots grow to different depths depending on environmental conditions such as:
- Soil packing and quality
- Oxygen or space
- Water source
Specifically, blueberry plants watered via drip irrigation usually have roots found close to the drip pipes. On the other hand, those that are watered with rainwater or sprinklers will have a more even layer of roots.
Raised beds generally have looser soils, so they promote deeper roots with blueberries. This can be an advantage as the deeper roots can access more soil, potentially leading to increased nutrient uptake.
Compared to clay soils, blueberry plants grow much deeper in sandy soils as it’s more spacious and acidic. Additionally, you can plant blueberry bushes in a pine bark layer, or with coffee grounds, which are also naturally more acidic.
This is one reason why pine trees make a great companion plant for blueberries.
Sometimes, gardeners are concerned that blueberry roots will damage pipes or structures such as foundations. So, is there any truth to this?
Can Blueberry Roots Damage Property or Structures?
The roots of blueberry plants are rarely the cause of foundation damage but can sometimes cause issues with sidewalks or pathways if they’re planted too close. This is due to the shallow root systems that spread horizontally just under the surface. For this reason, keep blueberry bushes at least 1-2 feet away.
While unlikely, blueberry roots can potentially damage:
- Pipes
- Sidewalks
- Other concrete pathways
- Parts of driveways
Some gardeners are divided on their thoughts about plants seeking out and damaging water pipes. So, what’s the verdict?
In the book The Hidden Life of Trees, German forester Peter Wohlleben busts the myth that a plant’s roots are attracted to water from water pipes. He writes that the more likely case why they’re attracted to the pipes is that they generally have looser ground, which allows for more air and space for root growth. Any water leaking from a pipe is more of a bonus for the plant.
So, if you’re planting blueberry plants near sidewalks, other concrete pathways, or pipes, it’s a good idea to keep the plants at least 1-2 feet away.
However, blueberry roots are not as strong as other, plants, such as fruit trees. For this reason, their roots are not likely to pose an issue.
However, if there is water under the foundation, roots can absorb this water and dry out shrinkable clay soils.
The most likely scenario is the blueberry’s roots displacing concrete as it absorbs the water found underneath it, causing the soil to shrink. However, these wouldn’t be very far, given they only grow outward to about 1 foot or so.
Shrinking soil can indirectly lead to damage with the depletion of soil moisture, causing the foundation to recede into the ground. But this situation is uncommon and a foundation’s age is a more likely culprit in its damage.
Still, it’s better to be safe than sorry. Because of this, plant blueberry bushes at least a foot or two from structures if possible!
How Far Away Should You Plant Blueberry Bushes From Other Plants?
As a general rule, plant blueberry bushes at least 1 foot away from other plants. This will help avoid root and nutrient competition. However, keep blueberry bushes within 50 feet of other flowering plants.
Simply put, it’s not likely that pollinators, such as bees, butterflies, and hummingbirds, will visit both the flowering companion plants and the blueberry bush with distances of over 50 feet.
To see more companion flowers, check out my other post: The Top 10 Companion Flowers for Gardens, Vegetables, & More.
So, planting your blueberry plant slightly apart from structures and other plants is the best way to prevent any potential root damage. However, what are some other methods of control?
How To Control Blueberry Roots
The best way to control blueberry roots is with a root barrier. You can also keep the tree in a raised bed or pot, or prune its roots. However, pruning a blueberry bush’s roots can stunt the plant and is more upkeep than simply keeping it in a root barrier or pot. For these reasons, pruning is best avoided.
Generally, you don’t need to worry about controlling blueberry roots. However, if you’re in a unique situation where you do, here are the best four ways to manage blueberry roots:
- Root barrier
- Root pruning
- Growing in a pot or container
- Growing in a raised bed
Root barriers are used to redirect the blueberry roots deeper into the soil and away from structures and other plants. This physical blocker protects your property as well as the blueberry plant. On the other hand, planting the blueberry bush in a pot will naturally bind its roots.
Keep in mind that it’s a best practice to provide your blueberry plant with a new, larger container and fresh potting soil every 3-5 years. If you feel comfortable, you can also prune the roots during this time to slow the plant’s growth.
