How UK Weather Extremes Affect Tree Health
- Elm Park
- Apr 28
- 8 min read
The UK’s weather can be a fickle thing – one year we’re hit by severe storms, the next we’re in a drought or late spring frost. These weather extremes can have a big impact on the health of our trees. In this post, we’ll explore how storms, heavy winds, prolonged wet or dry spells, heatwaves, and frosts affect trees in Britain. Understanding these effects will help you prepare and care for your trees to withstand the wild swings of British weather (which, let’s face it, seem to be getting wilder with climate change). From storm damage to drought stress, here’s what to watch for and how to help your trees cope.
Storms & High Winds
What Happens
Winter gales or even summer thunderstorms can break branches or even uproot trees. In recent years, you might recall images of trees downed after storms like Storm Arwen or Ciara. High winds put mechanical stress on trunks and limbs; waterlogged soil combined with wind can cause uprooting if roots lose their purchase in soft ground.
Tree Response
Trees sway in winds – that’s normal and even helps them develop strength (a phenomenon known as “wind-thrown” stress leading to adaptive growth). However, extreme winds break what’s dead, weak, or poorly attached. Common storm injuries include:
Broken limbs (especially on trees with dense canopies like Cedars or those in full leaf during summer storms).
Crown twist – where the wind torques the canopy and causes a crack down the trunk.
Uprooting or root heave on exposed trees or those in saturated soils.
Older or structurally imbalanced trees are more vulnerable. For example, a mature beech with decay might snap at the weakened point in a gale. A shallow-rooted species (like spruce or fir on thin soil) may topple in a high wind event when a deep-rooted oak would stand firm.
What You Can Do
Preventative care: Regularly remove dead or weak branches (a practice called deadwooding) so they don’t break off in a storm . Consider crown thinning on trees with very dense canopies – allowing wind to pass through reduces the “sail effect” .
Post-storm check: After a big wind event, inspect your trees. Look for hanging broken branches (often called “widow-makers”), cracks in major limbs, or newly leaning trees. If a large branch is cracked or a tree is partially uprooted, call a tree surgeon promptly . They have the skills to safely remove damaged limbs or, in some cases, cable brace cracked branches if appropriate.
Note on species: Some species are known to be brittle (like crack willow – Salix fragilis – it’s in the name!). Knowing your tree helps set expectations. If you have a eucalyptus, don’t be too surprised if a minor storm litters your garden with shed twigs and strips of bark; they shed loads in wind but usually to self-prune and spare major damage.
Drought & Heatwaves
What Happens
Although the UK traditionally has a temperate, rain-friendly climate, we’ve seen intense heatwaves and droughts (like the summer of 2018 or 2022 where hoses sizzled on lawns). In drought, soil moisture drops, and trees can’t uptake enough water. Heatwaves also mean higher evaporation from leaves, increasing water demand just when supply is low.
Tree Response
Leaf Scorch and Drop: Trees may show scorched leaf edges or browning between veins (especially maples, beeches, and other broadleaves). They might drop some leaves early (a defensive tactic to reduce water loss – essentially a mini self-pruning). In the record 2022 heat, some UK trees began shedding leaves as early as July due to heat stress.
Wilting: Particularly on younger trees or species like birch which have high water needs, you might see leaves wilting (limp, drooping). If relief (rain/irrigation) comes soon, they can perk back up, but prolonged wilting can lead to branch dieback.
Cracks in Soil & Stability: Drought on clay soils can cause significant shrinkage – you may see gaps around the base where soil pulled away. Besides stressing roots, this can affect anchorage slightly until soils re-wet. Some tree species also respond to drought by growing deeper roots if they can, or by slowing growth (forming a narrower growth ring that year).
Increased Vulnerability: Drought-stressed trees are more susceptible to pests and diseases. For example, a drought-weakened pine is more inviting to bark beetles. A study noted that severe drought can predispose oaks to attack by certain borers and opportunistic fungi once their defenses are down .
What You Can Do
Watering: During extended dry spells, especially for young or recently planted trees (under 3-5 years), deep water them weekly. A slow soak that penetrates to the rooting depth is vital – roughly 20–50 liters per young tree per week in drought . Even mature trees in urban areas benefit from a good watering during exceptional droughts (e.g., a drip hose around the dripline). Remember: it’s better to water heavily and infrequently than little and often, to encourage deep roots.
Mulch: Mulching with organic material (wood chips, compost) around the base (but not piled on the trunk) helps conserve soil moisture . A 5-10 cm layer can significantly reduce evaporation and also moderate soil temperature.
Shade / Windbreaks: For orchards or smaller ornamental trees, providing temporary shade cloth during an extreme heatwave (if feasible) can reduce leaf scorch. If dry winds are an issue, windbreak hedges or fences help reduce additional drying.
Don’t fertilize in drought: It might seem counterintuitive, but avoid fertilizing a drought-stressed tree – fertilizer salts can scorch roots when water is scarce. Focus on watering first; feeding can wait until conditions improve.
Frost & Snow
What Happens
Late spring frosts can nip emerging leaves or blossom. Hard winter frosts can cause bark to crack (frost cracks) or damage evergreen foliage. Snow loads, especially wet snow, can bend or break branches.
Tree Response
Frost Damage: New growth is tender. A late April frost might blacken young copper beech leaves or kill early flush of ash leaves. Often, trees push out a second set of buds (reserve buds) and recover, though fruit yields can suffer if blossoms were killed. Repeated spring frost can deplete a tree’s energy reserves.
Frost Cracking: Rapid temperature drops cause water in bark to freeze and expand. You may later see a vertical crack with exposed wood, usually on the south/southwest side of the trunk (where daytime sun warmed the bark, then night frost freezes it). These cracks can be entry points for disease but often trees compartmentalize them. They might appear as long scars. Young trees or those with thin bark (like young sycamores, or cherries) are more prone.
Snow and Ice: Snow can be quite heavy. Evergreens (pines, cedars) and multi-leader shrubs/trees can splay outward or branches can break under heavy snow or ice accumulation. You might notice bent branches that don’t spring back, or in worst cases, fractures at branch unions.
What You Can Do
Choose resilient species/varieties: If late frosts are common in your area (like in low-lying frost pockets), avoid planting very early budding species or choose later-budding cultivars. For instance, walnut trees often leaf out late, sparing them frost damage, whereas an early Japanese maple in a frost pocket might get zapped annually.
Protect young trees: For frost-sensitive young trees or those in blossom, you can throw a horticultural fleece or sheet over them on nights frost is predicted (for small trees it’s practical). This is common in spring for protecting fruit tree blossoms (like covering a fan-trained peach on a fence).
Mulch and Hydrate: A well-watered tree going into a frost is paradoxically better off than a dry one – moist soil holds more heat which can moderate temperature swings. Mulch insulates the roots from extreme cold as well as heat .
Snow Removal: If heavy snow falls, gently knock off accumulations from limbs that look stressed (use a broom to carefully push or shake branches upward). Don’t beat the trunk (you don’t want to cause other damage). For ice, however, do not try to break ice off branches – you’re likely to break the branch before the ice. Let it melt naturally .
Wrap delicate bark: In very harsh winter areas or for very young trees with thin bark, some people use tree guards or wrap the trunk in burlap for the coldest part of winter to prevent sunscald/frost crack. In most of the UK this is not necessary except perhaps for certain ornamental species from milder climates.
Flooding & Waterlogging
What Happens
Heavy rains and floods can saturate soils for extended periods. Roots need oxygen – waterlogged conditions essentially drown roots (they suffocate from lack of oxygen).
Tree Response
Chlorosis and Leaf Drop: If roots are under water for too long, leaves may turn yellow (from nutrient deficiency due to root dysfunction) and fall off. You might mistake it for drought response because it can look similar (wilting, leaf loss), but check the soil – it’s sopping.
Root Rot: Fungal diseases like Phytophthora thrive in saturated soils and can infect stressed roots. A tree that went through a flood might later develop root rot issues and show dieback.
Buttress Root Loosening: Flood currents can erode soil around roots. Trees might lose some anchorage or even tip if enough soil washes away.
What You Can Do
Improve Drainage: If you have chronic waterlogging where a tree is, consider remedial actions: vertical mulching (drilling holes and filling with gravel/sand to break up hardpan), creating drain channels, or raising the soil level (berming) when planting new trees. Choose species that tolerate wet feet (alder, willow, swamp cypress) for wet spots, instead of forcing a species like pine to suffer.
After Flood Care: Once water recedes, help the soil dry out by gently aerating the surface (a garden fork with shallow probes around the drip line), add organic matter to improve soil structure in the long term. Monitor the tree for signs of fungal infection in the following weeks.
Stake if necessary: If minor root heave occurred but the tree is salvageable (young enough to recover), you might stake the tree to stabilize it after re-firming the soil. Only do this for a season or so while roots re-establish.
The Climate Change Angle
UK climate projections suggest more erratic weather: wetter winters (hence more floods and storms) and hotter, drier summers . So, what does that mean for our trees?
We may need to plant with future climate in mind – perhaps favoring species that can handle drought or heat in southern England that historically were more Mediterranean (some experts suggest species like Italian stone pine, cedar of Lebanon, etc., might cope well with warming).
Greater stress from extremes can weaken trees, making them more susceptible to the “secondary” killers – pests and diseases. We might see more epidemic outbreaks (as stressed trees can’t fight off invasions as well). For example, continental Europe has seen more bark beetle damage after hot dry summers; the UK could face similar with our spruce plantations.
On the flip side, milder winters might let some trees grow longer into the season, but can confuse dormancy cycles and increase storm damage if leaves are still on during winter gales.
UK trees are hardy and have endured the climate for centuries, but the growing frequency of extremes means we have to be proactive. By understanding how a storm can break a weak branch or how a drought can stress a shallow-rooted tree, we can make better decisions in caring for and planting trees. So, brace your trees for storms, quench their thirst in droughts, shield them (a bit) in freezing winds – and they’ll be more likely to emerge from extreme weather with limbs intact and leaves aplenty. Weather will always keep us on our toes, but with attentive care, our trees can weather the weather!
Elm Park Tree Services is a team of NPTC qualified and highly skilled tree surgeons based in Abingdon, Oxfordshire. With over 18 years experience we can accommodate a project of any size. Get a quote today >
