I find it is easier to learn about gardening with my aging brain if I understand the underlying reasons for the tasks we need to do. Gardening is a huge, complicated subject to learn and no one ever does master it completely. So there is no danger of getting bored if you are interested in the first place. Here are a few examples of gardening jobs that are easier to understand and remember if you know the reasons for them.

Most gardeners know that if you have to move a peony, you do it in the autumn but not everyone knows why. Throughout the summer, peonies grow delicate feeder roots that feed the large storage part of the root. By the time fall comes, these small roots die off and the peony goes dormant for the winter. If you try to dig too soon, you will damage the delicate roots, thereby reducing the peony’s chances of making it through the winter. If you buy a peony in a pot, chances are the pot is full of these feeder roots and you should not disturb them any more than necessary as you put the peony into the soil. This is why, if it is at all possible, we move peonies in the fall.

We get a lot of questions about when is the best time to prune various types of shrubs. You could make a list and learn by rote which to prune when, but it is much easier to remember if you understand what is going on with the plants. For the most part, you are not looking for seed production from your shrubs but once the flowering period is over, the plant is putting much of its energy into seeds. It is best to cut these off as part of your pruning for the year, so pruning naturally follows just after flowering is done.

You do not want to leave pruning too late either because shrubs will start preparing for next year’s bloom and you are likely to cut off this growth affecting next year’s flowers.

When you prune your shrubs, they tend to respond by sending out a flush of new growth and this growth needs time to prepare itself for winter. For shrubs that flower late in the season, there is not enough time for this to happen if you prune right after flowering and it is best to leave them alone until they are dormant in the late winter or early spring. This is why, for the most part, we prune spring flowering shrubs right after flowering and late flowering shrubs in the winter or early spring.

There are only a few evergreen conifers that will respond well to pruning. Yews and cedars are the exception because they will sprout a bit from old growth. For the most part however, spruce trees, pine trees, even junipers do not sprout from old wood. If you cut them back to previous years’ growth, they will just stay the way you cut them, and there will be no new leaves. So there is no hope for people who have planted cute little blue spruces by their front door. Eventually, they will eclipse the sun and hide their house from the street. You can slow them down by pruning out half of the new shoots each year but you must leave some of the new growth. This is why for these trees, it is best to think about the mature size of the tree at the time of planting.

Everyone knows that plants need adequate moisture to survive or they will wilt and die. But there is a level of moisture in which they will survive, not wilt but they will also not grow. Photosynthesis is necessary for growth. If plants do not have enough water they close the pores in their leaves to conserve. When they do this, it also closes off the way they get carbon dioxide for photosynthesis. This is why plants need water to grow.

Not too many gardeners like weeds in their garden, but many do not know the reasons why many of these plants are so successful. Most gardens start off as a patch of bare ground. When this happens, an alarm goes off in Nature’s control room. Alert! Bare ground! Bare ground! Plants needed urgently! Weeds are ready for this. They produce thousands of seeds per plant, which remain viable for many years in the soil waiting for sun and a bit of moisture to germinate. Open ground, especially freshly tilled, is what they live for. A very effective weed control strategy therefore is either not to dig the soil or after digging, cover the surface with weed-free compost or mulch. At least if you cannot get rid of the weed seeds, you can keep them in the dark were they will not germinate.

When you are waging battle with pests, diseases and weeds of your garden keep in mind that survival is a difficult struggle for all plants and animals. You do not need to wipe out your enemies – you just have to tip the balance in favour of the plants that you want to retain. So if you have a serious infestation of sawfly larvae on your roses, hit them a couple of times with soapy water and let the birds take care of the rest. If you have a few weeds, gently pull them out or dig them without disturbing the underlying weed seeds and plant more plants to give them more competition. If you see mildew on your shrubs, prune them out so that the air passes through, and the mildew has a harder time surviving.