The RHS offers up 14 things in your garden that you think might work, but which actually don’t

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Published: Wednesday, 03 July 2024 at 10:36 AM


There are plenty of things to do in the garden, so why make more work for yourself? Gardening ‘myths’ abound, with even hardened gardeners becoming susceptible to them. The experts at the RHS decided to debunk a few key gardening myths, which we lay out below.

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Don’t miss our piece with expert rosarian Michael Marriott who also debunks a few rose growing myths too.

Digging for soil fertility

Wheelbarrow and Shovel © Ken Welsh/Design Pics Editorial/Universal Images Group via Getty Images

Many gardeners believe you need to dig to improve soil fertility. This is false, and digging actually releases soil nitrogen, which in fact can damage soil.

Here’s more on no-dig gardening

Pot Planting

Growing plants in pots
Growing plants in pots © Aina Apelthun / Contributor

There has been a long-time misconception that growing plants in a pot is better, but pot planting also causes limited root spread and increases the need for watering and feeding. With some exceptions, it is better to plant in the ground.

Here’s ideas for summer container planting

Crocks in pots improve drainage

Gardeners have long believed that crocks in pots improve drainage, but this is false. Disrupted capillary action and reduced soil volume mean they don’t help. Instead, crocks can be helpful for gardeners to prevent the compost from dropping through the hole at the bottom of the pot.

How to compost without the faff

Not watering in the sun

Watering plants
Watering plants © by Jakub Porzycki/NurPhoto via Getty Images

A long-held misconception is that watering in the sun scorches leaves. Though it is best to water at ground level, scorching does not happen. Scorching to new plants from lack of hardening off is far more common.

When to water plants in hot weather

Planting holes in clay soil

A common myth among those planting in clay soil is that it is best to make a large planting hole to fill with grit. However, this creates a sump, so the roots get waterlogged and rot, harming the plants.

How to grow a sustainable garden

Deeper soil isn’t necessarily better

A woman planting a small seed
Deeper soil isn’t necessarily better © apos tophy/Getty

Many gardeners believe the deeper the soil, the better. Around 15cm is enough, 25cm at the very most. Those planting should use sharp sand rather than costly topsoil for deep beds.

Raised beds aren’t necessarily best for growing vegetables

Raised beds aren't necessarily better to grow vegetables in
Raised beds aren’t necessarily better to grow vegetables in. © PaulMaguire/Getty

While raised beds can help in wet regions and clay soils, they can lead to over-draining, are expensive, and use environmentally significant resources elsewhere.

Here’s more raised bed ideas

Vinegar isn’t a good weedkiller

Contrary to popular opinion, vinegar is not a good weedkiller as it won’t touch grasses and only harms broad-leaved seedlings, not larger plants.

Houseplants don’t purify the air

House plants in pots on a table
Do house plants purify the air? © Yulia Naumenko/Getty

According to our research, houseplants do not purify the air. Unlike ventilated homes with sparse plants, the original study was carried out in sealed growth chambers crammed with plants. There are plenty of other good reasons to grow houseplants, though.

Here’s our piece on common houseplant problems.

Coffee grounds don’t deter slugs

The evidence for coffee grounds’ ability to repel ants and slugs is poor. The same applies to myths about eggshells, grit, pumice, and many other products.

Looking for organic slug control?

Tomato leaves don’t need to be removed

makeshift home garden on a balcony, with a variety of seedling plants ready to be planted outdoors. Home grown produce in the making.selective focus on the foreground, close up images with blurred background

It has long been believed that bottom leaves should be removed from tomato plants. However, even lower leaves contribute to the plant until they go yellow (when they can be removed).

There is such a thing as over manuring

A big heap of manure in a field
There is such a thing as too much manure in gardens. © Santiago Urquijo/Getty

Although many believe there is no such thing as too much manure, organic matter, or compost, this is wrong. Overmanuring leads to excess heavy metals, phosphorus, and pollution.

Tree roots go as deep as the tree is tall

Tree roots form a shallow but broad ‘plate’ of roots and go wide instead of deep.

You don’t need to fertilise every spring

It is believed you must add fertiliser every spring. However, most plants don’t need feeding.