Weeds Growing Around Trees and Shrubs?
Using weed killer near established plants requires care. The wrong product — or the wrong application method — can damage or kill trees and shrubs you want to keep.
The Risks: What Can Go Wrong
Trees and shrubs can be damaged by weed killers in three main ways:
- Root uptake: Systemic herbicides like glyphosate that reach the soil can be absorbed by tree and shrub roots. This is the biggest risk with any soil-applied or heavily sprayed treatment near established plants
- Spray drift: Fine spray droplets carried by wind onto leaves. Even a light breeze can carry herbicide particles several metres from the target area. Broadleaf herbicides like 2,4-D and fluroxypyr can severely damage ornamental shrubs, roses and hedging
- Vapour drift: Some herbicides (particularly 2,4-D ester formulations and dicamba) can volatilise in warm weather and drift as vapour, damaging plants that weren’t directly sprayed
Damage symptoms vary. Glyphosate causes gradual yellowing and dieback over weeks. Broadleaf herbicides cause leaf curling, twisting, and abnormal growth. By the time symptoms appear, the damage is done — there’s no antidote for herbicide exposure.
Understanding Root Zones
The most common mistake is underestimating how far tree roots spread. A mature tree with a 5-metre canopy radius may have feeding roots extending 10-15 metres from the trunk. The fine, absorptive roots that are most vulnerable to herbicide uptake are typically in the top 30cm of soil and extend well beyond the canopy edge.
Which Herbicides Are Safer Near Trees?
Key principle: Selective broadleaf herbicides (MCPA, mecoprop-P, 2,4-D) are safe around grass but will damage any broadleaf shrub or tree they contact. Brushwood killers (fluroxypyr, triclopyr) are specifically designed to kill woody plants — keep them well away from any trees or shrubs you want to keep.
Safe Application Methods
Spot treatment with a weed wiper or paintbrush: The safest method near trees. Apply glyphosate directly to weed leaves using a glove-and-wipe technique or a wick applicator. No spray means no drift. This works well for individual weeds growing near tree trunks or within shrub borders.
Low-pressure targeted spray: If spraying is necessary, use the lowest pressure setting and a coarse nozzle to produce large droplets that fall directly onto the target. Fine mist drifts — large droplets don’t. Keep the nozzle as close to the weeds as possible.
Shield spraying: Hold a piece of cardboard or plastic sheet between the spray nozzle and the plant you want to protect. This catches any sideways drift. Particularly useful when treating weeds at the base of hedges.
Calm conditions only: Never spray near valued plants in any wind. Even a light breeze you can barely feel is enough to carry fine spray particles onto nearby foliage. Early morning or evening on still days gives the best conditions. Check our application timing guide for more on weather conditions.
Avoid rainy periods: Heavy rain after application can wash herbicide into the soil and towards tree root zones. Check the forecast and ensure at least 6 hours (preferably 24) of dry weather after spraying.
Non-Chemical Alternatives
Near particularly valued trees or in areas where the risk of chemical damage is too high, consider these alternatives:
- Mulching: A 10cm layer of bark mulch, wood chip or composted material suppresses weed growth while feeding the tree. This is the professional arborist’s preferred method — keep mulch 10cm away from the trunk to prevent rot
- Hand weeding: Labour-intensive but zero risk to established plants. Effective for small areas around specimen trees and in shrub borders
- Ground cover planting: Dense ground cover plants (vinca, ajuga, geraniums) compete with weeds and protect bare soil under trees
- Weed membrane: Landscape fabric covered with decorative bark or gravel provides lasting weed suppression around trees and in planted borders
Frequently Asked Questions
Will glyphosate kill my tree if I spray near it?
Glyphosate deactivates on contact with soil, so spraying weeds near a tree trunk is generally safe provided you don’t spray the bark, exposed roots, or foliage directly. The main risk is spray drifting onto low branches or suckers growing from the base. Use a shield and spray on calm days. If the tree has surface roots, avoid spraying over them entirely.
Can I use lawn weed killer under trees?
Selective lawn weed killers containing MCPA or mecoprop-P are safe on grass under trees but will damage any broadleaf growth. If your tree has low-hanging branches or suckers that might be sprayed, protect them with a plastic sheet. Avoid treating right up to the trunk — hand-weed the last 30cm.
My neighbour sprayed weed killer and it’s damaged my hedge. What should I do?
Herbicide drift damage from neighbouring properties is unfortunately common, especially with volatile products like dicamba and 2,4-D esters. The affected growth may recover if the exposure was light. Prune out severely damaged sections and wait for new growth. If the damage is extensive, photograph everything and contact your local council or a solicitor about liability.
How do I kill weeds around the base of a hedge without damaging it?
Glyphosate applied carefully with a weed wiper or paintbrush directly onto the weed leaves is the safest chemical approach. Avoid any spray touching the hedge stems or foliage. Alternatively, hand-weed or apply a thick mulch layer. For weeds growing through a hedge from the other side, you’ll need to treat them from that side to avoid hedge contact.
Is it safe to use weed killer on recently planted trees?
Young trees (under 2-3 years old) are far more vulnerable than established specimens because their root systems are smaller, shallower, and actively growing. Avoid all herbicide use within 1 metre of recently planted trees. Hand-weed or mulch instead until the tree is well established. Even glyphosate can set back a young tree if any contacts the thin bark.
Can tree roots absorb weed killer from a path or driveway?
Yes. Tree roots regularly grow under paths, drives and patios — cracks in paving are often caused by root activity. If you spray weeds growing through cracks in an area where tree roots are present, the herbicide can potentially reach the root system. Use a contact herbicide like pelargonic acid instead, which has no soil activity and won’t affect roots.
Need to Clear Weeds Safely?
Our weed killers range includes targeted products for safe use around garden plants. Read the label carefully and always apply with precision near valued trees and shrubs.
