Tree Care Diary – November

Fallen leaves in November

3 Tree Care Do’s and 3 Don’ts in November

1. DO think differently about tidying up those leaves this November

Look, we get it. Everyone with a lawn must cultivate it and nurture it to within an inch of its life to make it beautiful and even and green. Heck, some local community rules mandate that you keep your lawn tidy and cut. Whenever the fall drops a bunch of leaves on our lawns, we are conditioned to think we must rake, sweep, burn or blow them away without delay. But will grass give you shade in the summer and a wind break in winter? Will grass support a diverse range of wildlife apart from the occasional grazing herbivore that might wander into your yard? Will grass grow into an asset that could be worth $10,000 when mature? We doubt it.

Perhaps it’s time to prioritize your trees over your grass

Unless you feel absolutely compelled to present a perfect albeit somewhat artificial lawn landscape, we say don’t bother getting rid of fallen leaves this fall. With warm moist conditions still prevalent underground in November, worms are still very active and can remove many of the leaves for you. Fortunately, our National Wildlife Federation (NWF) agrees. They ask folk to reconsider how we respond to leaves on our grass this time round and in the future. NWF say that a bed of fallen leaves better resembles a forest floor. This serves to recycle decay nature’s bounty naturally and turn leaves back into nutrients for the soil in our yards. A layer of leaves also creates a micro-environment for various critters such as woodlice, thrips, earwigs, millipedes and earthworms that feed upon the leaf litter and break it down. Then fungi in the soil that have valuable symbiotic relationships with tree roots can then actively harness organic matter for future growth. Together, the critters and soil fungi help to recycle the leaves in a natural way. They liberate soluble and usable nutrients for the plants and trees that depend upon a healthy soil to survive. Leaves left on the ground can feed this positive cycle of life for the ultimate benefit of your tree.

Sometimes though, if leaves on a lawn are left in a thick layer, they can form unsightly bare patches in your grass over the winter period. So the NWF helpfully suggest that instead of removing the leaves entirely, gardeners could help accelerate the natural decomposition process by mowing the leaves in situ. In this way, leaves are turned into coin-sized pieces and mixed with cut grass when mown. This allows the grass to grow through and not die. It also gives the decomposition of the leaves a head start and more likely to be drawn down into the soil for consumption by earthworms, for example.

Alternatively, we suggest that, depending on your community or HOA regulations, you allow the leaves that are within the drip line of your tree at grade to decay naturally.

2. DO prepare your trees for the winter months

In some respects, a tough winter can help trees the following year by reducing numbers of harmful pests. That doesn’t mean that your trees to the ravages of inclement weather.

We agree that on the surface, your trees might look they’re in a state of suspended animation during the winter months. However, metabolism continues as they prepare to grow the following spring. This involves sap being moved around the tree between trunk, root system and branches.

The International Society of Arboriculture (ISA) therefore recommends that you assist the tree’s fluid management process and reducing winter stresses by preparing your trees for cold weather in the following ways:

i). Mulching – yes our old favorite but only if it’s done the right way. If the area underneath your trees has been swept, burnt or blown clean of leaves this fall, then create a layer of composted material beneath it. Why mulch in fall? Primarily, because it’s because a 2 to 3 inch layer of mulch will act as a blanket protecting the tree’s root system from the extremes of winter temperatures to come.

To mulch your tree properly, mark out a circular area beneath your tree that extends to its dripline. This is an imaginary area formed on the ground by the outer circumference of the tree’s above-ground canopy. Carefully remove any sod and turn the soil very gently. Be mindful that delicate tree roots may lie near the surface which must not be damaged. Spread no more than a 3 inch thick layer of organic matter out to as close as you can get to the natural drip line of the trees. Grass is a tough competitor for the tree’s roots, most of which lie within one or two feet below grade in a wide area. So removing the grass in this area will benefit your tree in the long run.

Mulching is a double-edged sword, however. On the one hand, mulching replicates the forest leaf litter which is continually being formed and broken down into usable nutrients. Recent arboricultural research shows that for young sapling trees, proper mulching can accelerate root development by 400%. This, in turn, leads to increasing the rate of growth by 20% each year. That’s a lot of tree!

Yet, on the other hand, mulching can suffocate a tree if the layer is too thick in two ways:
a). Over-mulching can prevent oxygen from reaching the roots which is needed for the roots’ metabolism, proper functioning and root growth; and
b). Mulch piled up against the tree trunk can irreparably damage the tree as it compromises a very sensitive area of the tree called the root flare. This is located at the bottom of a tree’s trunk and is where the trunk begins to flare out into the root system. It must never be covered by damp organic matter like mulch.

So ensure that you have no more than a 3 inch layer of mulch around your trees and keep this layer at least 4 inches AWAY from the root flare. Your tree’s root flare must always be visible above grade.

ii). Water your trees especially when they’re young and lack the reserves and root system of mature examples. Droughts occur in winter as well as summer. An occasional soaking when it’s not freezing will help your trees endure periods of little rainfall.

Some of the trees you have planted MAY be on the raggedy edge of what your local Hardiness Zone can support. For example, if your tree is rated for a Zone of 8 and your location is at a cooler zone 5 or 6 , they may be susceptible to unexpectedly low temperatures and damage called winterburn or sun scald. Conifers are among those tree species affected. Here, the needles turn brown and the tree looks dead. In extreme cases, it may have to be replaced.

The preventative solutions include deep watering before the ground becomes frozen. Application of ant-dessicants in certain situations could also help reduce the needles from drying out and becoming damaged. You should consult your local arborist regarding the latter option.

iii). Reduce risk of mechanical damage – Snow shovels and snow ploughs used near trees can harm them if accidentally clipped. If your yard is near to woods and wild animals then deer and other creatures can rub up against and/or nibble away at the bark. Use a flexible tree guard to prevent such damage especially on younger trees.

3. DO inspect your trees for pests

Infestation by spruce spider mites on conifers earlier in the fall can lead to a bronzing or rust discoloration of pine needles. This happens especially if the trees are stressed. Increase the tree’s resilience to such pests by watering as already advised. Spruce mites overwinter by laying small orange eggs in and on the needles and branch. Mites can also be dislodged with a jet of water but avoid this if the weather is freezing. In addition, we recommend organic pesticides such as horticultural oil or insecticidal soaps to keep mites in check over winter.

More on organic tree pest control in winter next month (December)

4. DON’T fertilize your tree in fall

Trees can’t utilize winter fertilizers as a rule as their metabolism has slowed right down. The fertilizer will either leach away with winter rains or burn the roots if it’s un-seasonally dry. The ideal way is to replicate nature by reproducing the forest floor by way of mulching.

5. DON’T apply lawn fertilizer

Avoid spreading chemicals to the area of grass underneath your trees for similar reasons outlined in point 4.

6. DON’T prune your trees in the fall

Fall is the worst time of year to trim your trees, despite what some experts say. At this time of year, the tree normally directs sap to the roots where they can still grow underground in preparation for next season.  Normally, pruning encourages new growth above ground because the tree is attempting to compensate for the unexpected loss of part of its canopy. So pruning in the fall forces the tree to surrender its sap back to the branches to aid growth. This new growth is spectacularly vulnerable to the first hard frost. And sap-laden branches can split when from the same forces that burst water pipes.

Just because over-zealous neighbors are pruning their trees the moment all the leaves have descended, does not mean you should follow their example. The trees want to go dormant as temperatures cool and daylight shortens; so we recommend that you don’t send your trees in the other direction by pruning in the fall.

There is an exception to the ‘no pruning in fall’ rule. Trimming of branches that are already dead and which may be in danger of falling during winter storms can take place for safety reasons. BUT if the dead branch needs a ladder to reach it then leave well alone until a professional tree trimming company like Tree Top Pros can help you. The dangers of well-intentioned amateurs using dangerous cutting equipment at height are too profound to mention.

We shall remind readers when it’s best to prune their trees, an activity to be reserved for mid-winter to early spring in our humble view.
Please see our Tree Care Diary Disclaimer here. Despite our best efforts, our tree care advice cannot be applied ubiquitously for all regions and locations in the USA due to latitude, longitude and elevation differences. In case of doubt, always seek advice from your local certified arborist.

Tree Care Diary - December
How to plant a bare root tree