Did you know that a mature oak tree could shed up to half a million leaves? Or a silver birch up to 200K leaves?
As every gardener knows, leaf mould, made from composted leaves, is the best SRF (slow release fertiliser) available. Nature is clever. Falling leaves decomposing on the woodland floor, drip-feed perfectly balanced nutrients of Nitrogen, Phosphorous and Potassium, the building blocks for plant growth, back to the very trees they have fallen from. This is all well and good for soils, gardens and plant growth, but with water it's a very different story. For a successful, algae-free natural pool or wildlife pond the water should be as low as possible in nutrients.
Autumn is a glorious season. All about trees and blazing leaf colour. Trees and water are a wonderful combination…Reflections, vertical and horizontal elements. Unfortunately leaves left in water are bad news for a natural pool or pond, leading to anaerobic conditions, nutrient imbalance, release of nutrients and algae problems in Spring. So how can you enjoy the beauty of trees and water yet manage the potentially millions of leaves that fall in and around your pond or natural pool this time of year?
Prevent leaves from entering the water by netting your pond or natural pool in Autumn. Small natural pools, particularly those with a geometric shape, are easy to fit with a net during leaf fall, which catches leaves before they enter the water. This can be planned for at construction stage with discreet fixings in place ready to install a net quickly and easily in autumn.
Here at Ellicar Gardens, we rake up the leaves daily from around our large natural pool. We find a large plastic leaf rake perfect for this job. We leave a bulk bag standing beside the water throughout Autumn and top it up with leaves every day, then cart it away to compost once it is full. This repetitive activity is great exercise and has a certain feel good factor about it, especially on a sunny, Autumn day. In fact I can think of far worse gardening jobs! the trick if little and often. Five minutes of leaf raking a day is better than a long, tedious, soggy session after a week of leaf fall.
For serious leaf control, we use a garden blower to blow the leaves away from the water’s edge, trap them somewhere and collect them- this is also great for a quick fix mid week, if you are short of time. Just make sure the leaves are well trapped, they have a sneaky habit of blowing back again.
The trick here is to net leaves out from the water’s surface before they sink to the bottom. Be vigilant about this- most leaves float for a while before becoming trapped amongst water lilies and marginal plants. They are quite easy to skim out of the water'r surface with a pool net on a telescopic pole. If they are not removed in Autumn they will sink to the bottom of the pool where they become tricky to remove.
During leaf fall, check pool skimmers twice a day. A pool skimmer is designed to trap surface debris and during Autumn it will be working hard catching leaves and may require emptying twice or even three times a day.
Leaves on the bottom of the swim zone are easily removed using a pool vacuum. This is best to do this once leaves have finished dropping, or during your natural pool’s winter service.
Leaves trapped amongst the reeds in the plant filter or beach area are easy to rake out using a plastic leaf rake. This is best done after leaf fall and during the winter service after the reeds have been cut back.
Be vigilant and check your entire natural pool for trapped leaves such as between boulders, under the decking overhang. Sometimes leaves become trapped behind the deck skirt of a jetty. You will need to remove these by hand.
Leaves that sink to the bottom of the regeneration zone (deep water aquatic areas) pose more of a problem – if left they will decompose and form a sludgy, black, anaerobic layer, which is bad news for your pool. These leaves are tricky to remove. We cut back some of the deep water aquatic plants during a natural pool’s winter service, so any leaves tangled up with the water plants are easily removed with a rake and net. Then we use the vacuum nozzle to carefully remove leaves on the top of the clay surface- not easy and a job best left to your pool service team.
If you are planning a new pond or natural pool and would like to incorporate trees around the water, bear in mind the implications of leaf fall. Some species are more suitable than others. We have planted over 270 specimen trees around our own natural pool here at Ellicar Gardens and have a few tricks up our sleeve when it comes to trees, managing leaves and water.
More about this in another blog though. Please feel free to contact us for further information about natural pools, swimming ponds and wildlife ponds and planting schemes around water.