Mark Lane explains which pot is best to use
When it comes to choosing the right container there are several options, so pick the one to best suit you
Clay
Clay has been used for centuries, namely terraco a. Being a natural product, it’s porous and over time takes on an aged appearance as a result of fertilisers and minerals in water. If positioned in shade and kept moist the pots will turn green from algae and moss.
Terraco a is perfect for Mediterranean-style or co age gardens. Some are glazed, so you can match pots to colour schemes. I like unglazed versions so the pot, soil and plant can breathe; in other words excess water doesn’t collect around roots, which can drown a plant. Air can also penetrate the clay and get to the roots, which is essential for healthy growth.
Ideally, buy frost-proof clay pots, as you don’t want to buy new ones every year. As a natural product, just like your plants, they can be recycled over and over again, break down easily if cracked, and crushed and added to soil to help with drainage. Extraction of clay from natural habitats does, however, affect the natural environment.
Plastic
Plastic pots are lightweight and cheap, but aren’t great from an environmental point of view. Unlike clay pots, which have natural insulation and can add weight for a tall po ed plant, plastic pots need additional weight if growing a large shrub or tree. They heat and cool quickly, which is why they’re used so much in the horticultural industry (although this is changing).
For good growing you need drainage holes and it’s a lot easier to make new holes in plastic pots compared to clay pots. Black plastic pots do heat up quickly and have no insulation properties and, because they’re petroleumbased, they have a considerable impact on the environment.
Avoid pots with ‘PVC’, ‘PS’ or polycarbonate. Sunlight degrades plastic pots, and many councils won’t take them in the recycling bin, but if you have lots then give them away or share them with local community gardens.
Concrete or stone?
Concrete planters have great insulation properties but can be very heavy, which makes them perfect for large shrubs and trees. However, concrete is porous so might need sealing to prevent the soil alkalinity changing over time (as lime leaches out into the soil), which can be toxic to many plants. Leave a concrete planter outside empty for a few weeks during rainy weather before using so the lime can be dispersed elsewhere, but ideally not back into soil. Finally, concrete has a number of negative environmental issues, so please consider this before buying. Stone containers have lots of character, are heavy, have natural insulating properties and are great for longevity, which can counteract any environmental concerns. There are alternative stone containers, known as ‘faux stone’, which are made from reconstituted materials to give the look of stone but are considerably more lightweight and cheaper. They often contain limestone, fibreglass and/or a resin.
Wood or metal
Wooden containers fit within a naturalistic or modern garden. Wood can be pressure-treated for longevity, stained or preserved, but not all preservatives are bio-friendly. Check old, recycled wooden containers as they may have been treated with preservatives containing arsenic. Wood will eventually rot, so in addition to opting for pressuretreated timber, consider lining the planter, too. For additional insulation recycle polystyrene tiles to line it, as well as using a plastic liner – old compost bags are perfect for this (remember to cut drainage holes in the plastic).
Metal containers look stylish but heat up quickly, so it makes sense to line them. Where possible use cork, a lovely natural product, and not polystyrene (unless you’re recycling from packaging). Metal containers will vary in weight; cast iron planters will be heavier than aluminium ones. Also, some metal finishes are damaged from fertiliser salts, and as metal is not porous, water won’t drain away naturally, so you’ll need to add drainage holes.Whatever container you decide to choose, make the most of it by growing plants that suit the environment produced by the material used.