Quote from Lee Garden Ninja on 14th May 2024, 11:16 am

Hi @sheep

Great question about root spread. The one thing to remember with hedges (some species which otherwise left would grow into trees) is that the root spread will nearly always match the ultimate height you let the plant get to. 

Think of bonsai. You can grow pines as bonsai that otherwise would get to 30 meters. But by restraining them and pruning, you can keep them to 25cm tall!

The same is true of hedges. They will naturally spread their roots and take up moisture from the soil, but if kept trim, they shouldn't adversely affect the rest of the garden. Of course, this depends on how big your garden is, which I don't know.

One option for smaller gardens or those scared by root spread is to choose the smaller varieties from that mixed hedge list above, avoiding hedge plants that otherwise would be trees, i.e. field maple and alder. They are the more vigorous hedge species. Choose shrubs instead to ensure fibrous roots rather than big root spreads.

• Dog Rose
• Guelder Rose
• Sea Buckthorn Hedge
• Elder Hedge
• Spindle Hedge
• Privet

https://youtu.be/1TNhzMjco2c

How do you work out how far tree roots will spread?

For other gardeners reading this, here's a brief beginner's guide to understanding root spread, mostly for trees which have deeper tap roots compared to shrubs which usually have more fibrous root systems.

• Research Tree or Shrub Species: Different tree and shrub species have varying root systems. Some have deep taproots, while others have shallow, spreading roots. Research the specific species you're dealing with to understand their typical root spread. Make note of the listed ultimate height and spread this can give you an idea of the maximum root spread.

• Observe Above-Ground Growth: The above-ground growth of a tree or shrub often reflects its root system. Take note of the size and spread of the canopy or foliage. In general, the root system will extend beyond the drip line of the tree or shrub, where the outermost branches reach.

• Look for Surface Roots: Some trees and shrubs, especially older or mature ones, may have surface roots visible above the soil. These roots can give you a clue about the extent of the root system below.

• Consult Experts: If you're unsure about the root spread of a particular tree or shrub, consider consulting with a certified arborist or horticulturist. They can provide insights based on their expertise and may even conduct root surveys using specialized equipment.

• Use Online Resources: There are several online resources and guides available that provide information on the root spread of common tree and shrub species. These resources can be valuable references for beginners looking to understand root systems.

• Be Mindful of Nearby Structures: When planting new trees or shrubs or landscaping around existing ones, be mindful of nearby structures such as buildings, pathways, or underground utilities. Avoid planting trees or shrubs too close to these structures to prevent potential damage from root intrusion.

• Monitor Growth Over Time: Keep an eye on the growth of trees and shrubs in your garden over time. As they mature, their root systems will also continue to develop and expand. Regular monitoring can help you anticipate any potential issues related to root spread.

• Consider Root Barriers: In some cases, you may want to limit the spread of tree or shrub roots, especially if they pose a risk to nearby structures or utilities. Installing root barriers can help contain the roots and prevent them from encroaching into unwanted areas.

Most of all, don't let planting a hedge put you off; just pick less vigorous species @sheep, and you won't go far wrong! Hedges, after all, are a wonderful wildlife habitat for all gardens!

Happy gardening 

Lee Garden Ninja

Quote from alan.lovell.ep on 17th July 2026, 8:26 am

You're asking exactly the right question because root competition can have more impact on neighbouring plants than people often expect.

Lee has already covered the general principle well: keeping woody plants regularly pruned does help limit the size of the root system over time, although the relationship isn't perfectly one-to-one. Soil type, moisture and the natural vigour of the species also play a big role.

A few thoughts on the species you've listed:

• Lower root competition: Spindle, Guelder Rose, Dog Rose, Privet and Red Stemmed Dogwood tend to be relatively easy companions in a mixed wildlife hedge.
• Moderate: Hazel, Crab Apple, Rowan and Bird Cherry generally behave well if given reasonable spacing and managed as hedge plants rather than allowed to become trees.
• More vigorous: Alder, Willow and Field Maple are the ones I'd be most cautious with in a smaller garden. Willow in particular is extremely thirsty and develops an extensive root system, while Alder also grows very strongly if conditions suit it.
• Sea Buckthorn: Great for wildlife, but worth remembering it naturally suckers, so it can spread sideways unless you remove new shoots.

If your aim is a hedge around 2 m high, I'd also recommend planting as a mixed hedge rather than large blocks of a single species. Mixing plants tends to spread the competition, improves resilience to pests and diseases, and provides flowers, berries and shelter over a much longer season for wildlife.

If you'll be planting herbaceous borders or vegetables close to the hedge, leaving around 1–1.5 m between the hedge line and intensive planting makes maintenance much easier and reduces competition for water.

One thing that's often overlooked is improving the soil before planting. Incorporating organic matter and applying a good mulch each year can make a noticeable difference by helping moisture retention and encouraging healthy root development without excessive competition.

If you're comparing different hedging species, the planting guides on Everything Plants are also a useful reference for expected growth habits, spacing and maintenance requirements

Best of luck with the project, it sounds like it'll become a fantastic wildlife hedge over the next few years. I'd be interested to hear how long the hedge is and whether your soil is clay, loam or sandy, as that can influence which combination of species performs best.