Getting plant sizes right in a garden design

Garden designers in Glasgow and elsewhere will always have the ultimate size of herbaceous plants, shrubs and trees in mind when creating planting plans and garden designs for their clients. In slightly more ‘robust’ climates such as we have in Glasgow (compared to the rest of the UK), some plants will not reach their full potential however, and this is where a degree of horticultural knowledge comes into making sure planting plans are accurate when creating garden designs.

Plant labels will always show the ultimate height and spread of the specimen that you have just
purchased, and more detailed labels will tell you how long it will take the plant to reach this size. You can also find this information easily online. For garden designers the consideration of plant size is most crucial when dealing with trees, specifically with trees that are going to grow too large. Trees are often planted too close to houses, or simply in a position where their ultimate size will look disproportionate. Tree roots can cause problems too, and you should bear in mind that a tree’s roots extend to at least the same extent as the crown of the tree (the ‘drip line’).

For shrubs this consideration of size and spread is mostly a cosmetic one, as well as being a way to ensure a plant is as happy, and therefore healthy, as possible. Garden designers will position shrubs in a place where their ultimate size will be in keeping with the size of the bed and the (ultimate) size of the plants already there. In practice this may mean that you initially have gaps in your flowerbeds that become overgrown with weeds. The trick here, if you are sure you will be able to keep on top of managing your plants like this, is to plant slightly more densely and then thin out or transplant plants as everything grows in. When garden designers are doing show gardens, plants are typically planted too close together in order to create instant visual impact, but to do this in a real garden requires careful trimming and pruning over the course of several years to keep plants from squabbling with each other. It should also be remembered that crowded plants are under a degree of stress and are therefore more likely to pick up pests and diseases. In my own garden, I keep fairly crowded flowerbeds and trim and thin out as required, whilst feeding them well to keep them healthy and robust.This management of shrubs to keep them to a proportionate size is not a recommended technique with trees. The reason for this is that it is likely that at some point that someone else will own your garden, and if they do not maintain that ‘small’ tree next to the house, before they know it they will have a large tree to deal with!

Tom Angel is a garden designer based at a studio in the west end of Glasgow. As well as being an award-winnning garden designer, Tom is a Chartered Horticulturist with extensive knowledge in garden and landscape maintenance. Tom qualified (with Distinction) in garden design in 2017, after many years running his own Scotland-wide horticultural contracting business from his base in Glasgow.