What's the best container material?
There is no perfect container material, each has different pros and cons. As well as the size, the main things you'll want to consider when choosing a container is what it looks like, its weight, durability, water retention and cost.
Weight
Weight is likely to be important if you are growing on a roof terrace or if you’ll want to move your containers from place to place. Plastic, metal and fabric containers are light. Wood and terracotta are heavy, particularly in the large sizes.
Water and Heat Retention
Some materials retain water better than others. Unglazed terracotta pots are porous and dry out faster than plastic pots. Metal containers get very hot in the sun and cold in the winter – line with bubble wrap to prevent this. Wood is a good insulator and helps maintain a more even temperature.
These tins come from Pizza Express restaurants who'll often be happy to give them to you. They can look pretty - the downside is that the metal will heat up in the sun, and the tins are not very large - just about big enough for one chilli - or a very small baby bush tomato!
What they look like
This is an important consideration, particularly if you are growing in view of neighbours. If using recycled containers, use your creativity to make them look attractive. Decorate them, cover them with trailing plants or arrange them in attractive patterns.
Cost
How much you spend on containers is as long as a bit of string – you can do it for almost nothing or spend almost as much as you like. There are many excellent recycled options. Sometimes you may want to invest in containers for a particular space. For example, I started with home made wooden boxes on my south facing window sills but found they were very heavy and needed constant repairs. Last year, I bought Earthboxes – because they were light, strong, gave good yields, fitted the space perfectly and are supposed to last (according to the manufacturer!) many years.
Hand made terracotta pots like this can look great and will last many years. The downsides are that they are heavy, dry out quickly, and expensive.
Drainage holes and Feet
All containers need plenty of drainage holes in the bottom. Use a drill or a nail and hammer to make more if needed. Water needs to flow freely out of the drainage holes. Stand the pot on feet if necessary. Take care not to let pots stand in water for too long – the soil will get water logged and the plants roots will suffocate.Contaminants
You'll also want to make sure that your containers are safe for food growing. Avoid re-using anything that has contained paint or chemicals. Also wood that has been treated with toxic preservatives (most external preservatives like creosote are toxic). And old tyres - tyres contain toxic chemicals that leach into the soil. You may be able to prevent some contamination by lining the tyres with strong plastic (eg old compost bags) to prevent the tyre being in direct contact with the soil.Materials: pros and cons
Below is a table that summarises the pros and cons of each material. In my next post I will share more ideas on recycled containers and where to source them (thanks for your ideas on Twitter!).
| Material | Pros | Cons | Notes |
| Plastic |
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| Polystyrene |
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| Hard wood |
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| Soft wood |
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| Metal |
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| Woven sacks and bags |
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| Unglazed terracotta |
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| Woven willow |
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