Low-carbon container growing

From choosing your container to picking your plants, there are lots of easy ways to make sure your potted garden is a sustainable haven

Although potted plants have a smaller role to play than plants in the ground, they still take carbon from the air. Indoors, they’ll also help create a more natural environment by absorbing pollutants and oxygenating the air. Manage them sustainably and you’ll maximise those benefits.

Sustainable ways to grow plants in pots

Part 1 - choosing your pots and plants

Use second-hand containers: look in reclamation yards, vintage shops, and online auctions for zero-carbon pre-loved planters. Choose the biggest you can: With a few exceptions, the larger your pot, the more your plants can spread out their roots. Choose pots that have a diameter of at least 45cm (18in). Or build your own planter boxes from reclaimed wood.
RHS How to Garden the Low-Carbon Way
RHS How to Garden the Low-Carbon Way
Grow plants that like container life: Plants that are happiest in containers are relatively slow growing, with naturally small root systems, such as dwarf (“patio”) fruit and veg, small shrubs like skimmias, and herbs.
Use pot dishes: Catch and recycle water and
To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth.

nutrients by using containers with saucers or reservoirs wherever possible.
Plant permanently: Permanent shrubs, trees, perennials, and grasses absorb carbon over the longest period and generally need less compost, water, and fertilizers than hungry, fast-growing bedding plants.

Make your own potting compost

Going peat-free is vital for sustainable gardening. However, the only truly low-carbon way to grow in containers is not to buy compost at all, but to make your potting mixes at home.

Mix your compost as needed. You don’t have to mix huge amounts at a time – use a loaded spade as the measure for a wheelbarrow load, or a trowel if all you want is a bucketful.

For potting on and containers:

4 parts loam
1 part garden compost, municipal green waste, or well-rotted manure
1 part leaf mould
1 part sharp sand
1 heaped trowel of seaweed meal per loaded wheelbarrow

This is a basic mix. Add more sand for alpines and herbs, and use composted bracken instead of garden compost for acid-loving plants like blueberries.

Part 2 - sustainable techniques

Grow from seed: Raise your own annual flowers, bedding plants, or vegetables from seed, sown into pots of home-made compost.
Don’t change all the compost: When replanting annuals in spring, leave as much
Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

compost undisturbed as possible by digging out and replacing only the top 5cm (2in) of old compost.
Use captured rainwater: Plants prefer rainwater, as it’s full of nitrogen and slightly acidic (unlike tapwater, which tends to be limy). You’ll avoid all the emissions involved in treating and transporting tapwater, too.
Feed with home-made fertilisers: Artificial fertilisers are another source of greenhouse gas emissions (and tricky-to-recycle plastic bottles) so make your own.
Grow a container fruit garden: Potted orchards of fruit trees and berries are the ultimate in sustainable container growing, majoring on permanently planted, carbon-rich woody trees.

More low-carbon gardening ideas

How to grow a low-carbon garden

Using sustainable materials

Planting a low-carbon garden

Make a low-carbon wildflower meadow

Grow your own garden sundries

Grow a potted mini orchard

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Combatting climate change through gardening

RHS How to Garden the Low Carbon Way

Packed with practical gardening solutions to environmental problems and backed by the latest scientific research, RHS How to Garden the Low Carbon Way is perfect for gardeners looking to reduce their carbon footprint.

RHS How to Garden the Low Carbon Way

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