Plastics in the garden

In principle, organic growing uses non-renewable resources, such as plastic, as little as possible. And its use should have minimal impact on the environment. However, any gardener will encounter plastic at some stage – from pots to polytunnel, wheelbarrows and watering cans.
Here we discuss the different types of plastic, whether any are acceptable, and what you can do to reduce the amount in your growing area.
With an estimated 500 million plastic pots and trays in circulation in the UK, and very few of them recyclable, something has to change.  The sustainable route is to reduce the amount of plastic we use, always reuse if possible, and check that the plastic is either made from recycled material, or can be recycled itself.

Guide to plastics in the growing area
There are 7 types of plastics commercially processed and sold.  They are all made from polymers, usually sourced from petrochemicals.  A few are made from plant starches (see below for Bioplastics). The following guide will help you decide if you want to use, reuse, or not use them in your growing area:

PETE or PET bottles. Used in most clear drinks bottles. Can be adapted for use as cloches on tender young plants.  However, many bottles are produced for single use, and therefore can break down with continued use and exposure to light or heat, leaving residues in the soil. They have also been found to leach chemicals if exposed to high temperatures.  Recyclable.

 

HDPE (high density polyethylene). Used for “cloudy” milk and detergent bottles.  Can be used as bird deterrents in ‘scarecrow’ structures.  Also as water or liquid feed carriers.  Hard to break down. Recyclable.

 

PVC (polyvinyl chloride).  Used extensively as a rigid light plastic – from water pipes to wheelbarrows and most other tools.  Like HDPE, it is hard to break down, however, constant exposure to heat will cause chemicals to leach.  PVC often has chemicals called ‘phthalates’ added to make it more durable and flexible. Research has shown that phthalates affect our natural hormones, and can lead to reproductive abnormalities. Not generally recyclable, needs specific recycling processes.

 

LDPE (low density polyethylene). Used in shrink wraps, food storage bags and squeeze bottles.  Commonly used in the garden as potting compost bags and polytunnel covering. Reusable, but not usually recyclable. See below for recyling information

 

PP (polypropylene). Used in rigid containers such as yoghurt pots, margarine containers and microwavable meal trays etc.  It has good resistance to wear and tear, and is the second most produced plastic (after PVC) with 68m tons produced annually worldwide.  For the gardener, PP is used in flower pots, plant trays, ropes and netting.  Can be reused, and is generally recyclable - unless black. (Most of the black flower pots from garden centres is made from recycled plastic.)

 

Polystyrene. Used in food and beverage takeaways, non-cardboard egg cartons and CD/DVD cases. Styrene is classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC). It should avoided for use in the garden. Not generally recyclable, needs specific recycling processes.

 

This umbrella designation covers various resin mixes and other specific forms of plastic packaging.  Many are extremely toxic and they are generally not recyclable. They should be avoided in the growing area.

 

 

 Bioplastics
These are made from renewable resources such as vegetable fats and oils or plant starch.  This means they can be made from large scale agricultural by-products, which are often genetically engineered.  They have an advantage over petrobased plastics in that they use less fossil fuels in their production and will degrade more readily.  They are increasingly used for disposable items, such as packaging, crockery, cutlery, pots, bowls, and straws.  Some are compostable.  However they often need sufficient heat (and time) before rotting down.  Research is ongoing as to the residues they leave when biodegraded.

Use of plastics in the growing area
Most gardeners are surrounded by plastic – watering cans, flower pots, plant trays, wheelbarrows and netting.  And in truth there are some advantages to plastic.  It is
• Long lasting and durable
• Lightweight – particularly helpful for containers on a balcony, for instance, or to maximise ease of use
Objects made from recycled plastic keeps plastic out of landfill.
However, we know how damaging plastic is to the natural world.  From its manufacture to its disposal, it destroys or poisons much of the environment.  And it is therefore contrary to the organic principles of working in harmony with nature.

How can we reduce our plastic use?

  1. Can you use an alternative?  Wood, terracotta, stone, glass and natural fibres are all viable in most instances.  And can be recycled.
  2. As a consumer, you can put pressure on retailers to reduce their plastic footprint. Ask your garden centre to source fibre or bioplastic pots, trays and netting.  The horticultural industry is working towards providing alternatives, they need your support as a customer. 
  3. Also ask if they provide recycling facilities for black flowerpots and trays. Black cannot be picked up by the laser beams in most recycling facilities. This means most local authorities don't accept black plastic objects.
  4. Plastic sheets for mulching can be replaced by thick layers of cardboard and newspaper.  Or organic matter such as well rotted garden compost or manure.

Plastic in tea bags
Many tea bags have a small amount of plastic in them, to help seal the bag.  See here for further information on how and whether to recycle tea bags.

Recycling LDPE
A specialist firm in Norfolk will recycle LDPE plastics.  This includes compost sacks, clean cling film and plastic bags.  As well as the polyfilm used to wrap The Organic Way.  See here for their details.