Somewhere between Anzac Day and Queen’s Birthday weekend, the street trees and backyard deciduous trees across most of New Zealand let go of their leaves. For a few weeks the lawn turns gold, then brown, then soggy. Most of that leaf litter is harmless and even useful. The part that causes trouble is the fraction that ends up in spouting, downpipes and sumps, just as the wetter months arrive.
Blocked gutters are one of the most common reasons for water getting into ceilings and wall cavities in older homes. The fix is not complicated, but timing and a little planning make it much easier.
Which trees cause the most trouble
Not all leaf fall is equal. Large, flat leaves such as plane, liquidambar and oak tend to lie across gutter outlets and form a mat that seals the outlet like a plug. Smaller leaves from birch and some maples break down quickly into a fine sludge that slows flow and feeds moss. Needles from pines, macrocarpa and other conifers are a year-round problem rather than an autumn one, and they knit together into a felt that is surprisingly hard to dislodge.
Evergreen natives are not off the hook either. Pōhutukawa drop leaves and stamens through summer, and many eucalypts shed bark strips and leaves in bursts after hot or windy spells. If a house sits under a mix of species, expect the gutters to need attention more than once a year.
Timing the clean
The best time for a thorough clean is after most of the leaves have fallen but before the long run of winter rain. In the Bay of Plenty and Waikato that is often late May to mid-June; further south, a few weeks earlier. A clean done in early April simply fills back up within a fortnight.
Weather patterns are worth watching. Seasonal outlooks from NIWA give a sense of whether a wetter or drier than usual autumn and winter is expected, which helps decide whether one clean will do or whether a second pass is worth planning. A wet La Niña-leaning winter on a section under big trees is a strong argument for checking twice.
Doing it safely
Falls from ladders send a steady stream of New Zealanders to emergency departments every year, and gutter cleaning is a classic cause. A few habits reduce the risk considerably:
- Use a ladder rated for the job, set at roughly one metre out for every four metres up, on firm, level ground.
- Have someone foot the ladder, and do not lean out sideways. Move the ladder instead.
- Avoid working on a wet or mossy roof. Corrugated iron is slippery and concrete tiles crack underfoot.
- For two-storey homes or steep roofs, leave it to someone with proper access gear.
Scooping by hand with gloves and a small trowel into a bucket works better than blowing debris out, which tends to push it into downpipes. Finish by flushing each run with a hose and watching that the water actually arrives at the bottom of the downpipe.
Guards, mesh and pruning back
Gutter guards and mesh come in many forms, from simple clip-on plastic to powder-coated aluminium mesh fitted under the first row of roofing. Good mesh reduces cleaning, but it rarely eliminates it. Fine debris still collects on top, and mesh can trap needles. Installed costs vary widely depending on roof length and access, and are typically in the low thousands of dollars for an average single-storey house.
Often the better long-term answer is reducing how much canopy hangs over the roof. Lifting the lower limbs or reducing branches that extend over the eaves, done properly by an arborist, can cut leaf load significantly without harming the tree. Where a tree also serves as a windbreak, any pruning needs to balance shelter against leaf fall; the trade-offs are similar to those discussed in this piece on shelterbelts and fences on windy sections.
Before cutting anything significant, check whether the tree is protected under the district plan. Rules differ across councils, and street trees belong to the council regardless of how much of their leaf fall lands on private roofs.
Putting the leaves to work
Raked leaves are one of the most useful free materials a garden produces. Shredded with a mower and piled in a wire cage, they turn into leaf mould within a year or so, which makes an excellent soil conditioner. They can also be spread directly as a light mulch on garden beds.
Frequently asked questions
How often should gutters be cleaned under large trees? Usually at least twice a year: once after the main autumn drop and once in spring. Sections under conifers or pōhutukawa may need an extra check in summer.
Do gutter guards stop the need for cleaning? They reduce it, but most still need occasional brushing or flushing. Fine debris and needles can sit on top of mesh and slow water entry.
Can a neighbour’s tree be cut back because it fills the gutters? Overhanging branches can often be trimmed back to the boundary, but it is wise to talk to the neighbour first and check the district plan for any protection on the tree.