Odeur Sourire/PexelsWith wintry weather underway in many parts of Australia, I’ve been enjoying the seasonal change in my garden and its trees.Following the busy spring, summer and autumn seasons, things slow down in winter and I can have a really good look at what is going on with plants and soils.In fact, winter is a really great time to get a few important jobs done in the garden.1. Making the most of mulchStart by checking the depth and spread of mulch. Mulch will keep soils moist, acting as an insulating blanket to keep soils warmer and it always makes weeding easier.Knowing your mulch was perfectly fine in spring can lead to a false sense of security. Mulch can break down rapidly over the warmer months – so check now to ensure a 75-100 mm depth and proper coverage over areas you plan to plant out in spring. Use any fallen autumn leaves as part of your mulch; never underestimate the value of mulch and leaf litter to keep soils hydrated, healthy and full of nutrients.2. Tackling disease and pestsTake this time to remove any pest- or disease-affected foliage. Look for clues such as:coloured spots on leavesleaves that have already started to rot, andold leaves sheltering insects.This is part of general good garden hygiene, but can be particularly important for fruit trees and roses, which are prone to seasonal attack. For example, old leaves and fruit can harbour the insect pest codling moth, while black spot, rose rust and mildews are common in old rose leaves.Ensure tools such as secateurs are kept clean and disease-free by using a disinfectant. Methylated spirits or a diluted (10%) household bleach gets the job done.3. Checking trees and branchesWinter gives you a chance to see through deciduous trees. Examine the branching structure in detail and try to spot any branches that look dead, cracked, or as though they are only just hanging on. Dead branches are more likely to fall in strong winds, so make sure you remove them before any big winter winds hit.More generally, healthy and well-maintained trees are great at reducing the impact of winds.One Canadian study found that even leafless trees effectively buffer wind. In fact, removal of all of the trees around a building resulted in massive increases in wind speed and building energy costs.Winter is an ideal time for checking how stable any large trees are.If you are worried about a large tree falling over in a storm (also known as “windthrow”), go out on a couple of windy days when the wind is blowing from different directions. Check for any movement of the tree or the soil around the its base.Place your hand on or lean your back against the trunk; you should feel a gentle swaying in the wind but nothing jerky. If there is movement in the ground or jerkiness, call an arborist immediately.4. Looking at lichenLichen grows on trees as an epiphyte (meaning a plant that grows on another plant). It does no harm and tells you the air quality in the tree’s vicinity is generally good.Lichens are very sensitive to airborne pollutants and it is a delight to see them growing well, especially if you live near a busy road. So winter – when branches may be bare and easier to see – is a great time to check your local air quality by looking for lichen. Lichens are very sensitive to airborne pollutants. Photo by Caleb Wright on Unsplash 5. Checking for wet and dry spotsMany parts of Australia this year experienced very mild, warm autumn conditions.If you planted in autumn, make sure the plants’ root systems don’t dry out between winter showers. You may have to protect plants from frosts until they reach a height that escapes the frost zone. Because cold air is denser and heavier than warm air, it sinks to the ground surface and so the frost zone tends to be to a height of about 1.5-2.0 metres above ground level.You can protect plants from frosts by keeping soils moist; wet soil stores more heat during the day than dry soil.You can also cover plants with a light wet cloth or spray them with water, which will keep temperatures at around zero degrees rather than in the negative frosty range.Winter is a good time to check for wet and dry spots in your garden and take care of irrigation maintenance. Look for places that are consistently drier than other parts of your garden. These may be ideal for growing plants that need less water, but they may also be places where your irrigation regime or system is not working as well as you had hoped.You can also use this time to check irrigation lines for damage, cracks or tears. Ensuring they work well will help save water now and in the warmer growing months ahead.A time for taking stockGrowth in the garden slows in winter, giving you time to take stock of what’s going well and what you want to improve. Time will flash by, as it always does, but you can make the most of winter by planning for spring.Gregory Moore does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.