Top 10 gardening mistakes (and how to avoid them!)

Watering the garden with a hose

Gardening is all about trial and error, but to save time, money and heartache, here are 10 common errors that are easy to avoid…

1 Wrong plant, wrong place

It was the late Beth Chatto who came up with the adage ‘right plant right place’: a mantra for gardeners everywhere. The fact is, if you plant a shade-loving plant such as a hosta or hydrangea, in a bright sunny spot, its lush green leaves will soon turn a crisp yellow and fall off. It’s far safer to partner sun-loving Mediterranean plants with a suntrap, and lush woodlanders with a shady glade.

The upshot is, experienced gardeners tend to let their garden (particularly its aspect and soil) dictate what they can grow, rather than struggling against the conditions to accommodate a finicky favourite.

2 Planting too close together

We’ve all done it – been seduced by the voluptuous planting schemes in RHS Chelsea show gardens, where plants are crammed in at a rate of about 30 plants per square metre, when it should be about six at most.

Labels that include a plant’s eventual height and spread are very helpful when you’re shopping at the garden centre. If you take note of how much space a plant will need to grow into, you can give it the exact space it needs, and avoid having to prune it or move it in future. It also means your plants won’t sprawl in an ungainly fashion over their neighbours.

3 Overwatering houseplants

The main cause of houseplant death is over watering: a form of ‘killing with kindness’. Decorative houseplant pots seldom offer any drainage, so all too often they’re left to sit in water and rot. Instead, poke your finger into their compost before watering, to see how dry they are. Or, lift their inner pot to see if they’re sitting in an outer reservoir of water; if so, tip the water away and let them dry out for a day or so.

Dead conifer in terracotta pot
Dead conifer in terracotta pot

4 Neglecting container plants

While it’s all too easy to over water houseplants, the reverse is also true: we tend to under water our outdoor container plants. This is because we imagine that it rains all the time. Often, our potted patio plants are sitting in a ‘rain shadow’ – permanently sheltered by a porch, large shrub or overhanging roof. Container plants are totally dependent on us to meet their needs for water and water-soluable nutrients, so keep an eye on their compost moisture and be ready to give them a regular dousing in a dry spell.

5 Hard pruning delicate shrubs

Some shrubs respond well to a good pruning, others can be hacked to death. The secret is to understand the difference between those two types of plants. Speed of growth is a good indicator of how well a plant will respond to pruning, and most of them can be pruned either while dormant or straight after flowering, depending on when they flower and whether they flower on new or old stems. If in doubt, only prune shrubs if they’re really outgrowing their space (see point 2), and then, only cut back by one-third straight after flowering, and see what happens.  

6 Not pruning vigorous shrubs

Rampant giants such as buddleia, rambling roses and Clematis montana are famous for their vigour. For instance, Buddleia davidii can grow 2m (6½ feet) in a season and then self sow everywhere in the process, if you don’t deadhead it. If you have a small garden it’s best to stick to slow-growing trees and shrubs, or step up for regular annual pruning duties and invest in a good ladder.

7 Digging too much in winter

It’s one thing forking over the veg garden in autumn to clear it of perennial weeds, but quite another to start digging it over and raking to a fine tilth ready for spring. Frost will do the hard work of breaking up any large clumps of clay, so there’s no need to chop up the soil and rake too early. By overdigging before winter set in, you can unwittingly create a cap on the soil that’s pummelled and compacted into a hard crust by rain. Besides, no-dig champion Charles Dowding says it’s better for soil structure and friendly mycorrhiza if you simply dump a load of compost on top each spring. Job done.

Bags of manure from friendly horse owners are like ‘black gold’ to gardeners!

8 Forgetting to add organic matter

Most of us complain our soil is awful, save for a lucky few who live in fenland or fine silty river valleys. But alas, it’s no good just ignoring it. No plant can flourish in a compacted, heavy clay that bakes to concrete in summer, or a gravelly sandy pit that’s dry as a bone all year round. Some soil improvement – through the active addition in spring of well-rotted organic matter – will work wonders. Digging in organic matter (leafmould, year-old horse muck, compost, soil conditioner) improves soil structure, nutrient levels and drainage, and helps sandy soils hang onto moisture and nutrients. Plants love it.

9 Laying tarmac instead of gravel

Every family has at least two vehicles on their drive nowadays, so it’s all too tempting to turn your front garden into a plant-free forecourt that you don’t have to mow. However, this creates a problem of rainwater run-off and increases the risk of localised flooding after heavy storms. Gravel is a better option because this lets water soak away into the soil. Plus you can plant into it and where there are plants there’s the potential for wildlife.

10 Planting leylandii

This ungainly conifer grows at a frankly shocking rate of 75-90cm (2-3ft) per year, even in poor soils. The tallest on record is 39m (130ft) – that’s taller than the Tower of London. Source of many a neighbourly dispute, leylandii is still very popular and often used as a hedges of shelterbelt trees in windswept farmland. For more urban areas, we prefer the more attractive, slow growing options that don’t suck all the moisture out of the soil and block all the light, such as smart beech (Fagus sylvatica), wildlife friendly hawthorn (Crateagus monogyna) or a line of pleached hornbeam (Carpinus betulus).