Plants need to work together in a way they naturally would in the wild; either competing with each other so that only healthy disease-free specimens survive or supporting each other against predators in companionate ways. In order to fulfil their role plants also need to belong to their ecosystem rather than being apart from it. This means offering nutrition to invertebrates and birds, consolidating the soil and feeding it with rotting matter to improve its' fertility.
Many of our most important and endangered species of animal are dependent on particular species of plant for their survival. With six million hectares of land within British gardens there is a huge opportunity to secure the future of these species by planting the right plant in the right place. Although this generally represents a return to good old fashioned gardening principles there is also a lot of research going into modern planting techniques that are beneficial to wildlife. For instance the University of Sheffield is developing seed mixes where very attractive herbaceous perennials are chosen which are perfect companions, that don't dominate each other and don't let weeds through. Maintenance is very low and the effect and upkeep is very similar to that of a meadow.
Many of the native hedgerows that can be seen around the country are older than our houses. Hedgerows are a vital habitat for many animals. There is a potential to consider hedges more often in gardens. When well-planned they can enhance the natural feel and also make a great intruder barriers. Their traditional look does not mean they cannot also work in a modern design and their wildlife value is not only of benefit but also attracts animals that will in turn keep pests such as slugs under control.
When planting it is best to avoid the use of peat in compost. The majority of peat comes from the Irish peat bogs, which take millennia to establish. Its use is therefore categorically unsustainable. The peat bogs are an important and dwindling habitat for many species of wetland insect and birds. Again it has to travel a long way to get here so the embodied energy is high. Recent trials are showing that compost from Leylandii has better water retention than peat and could become an effective substitute. Compost can be bought from council-run composting schemes so it is sourced locally. The compost stack is the nerve centre of a well-run garden. If you would like your own compost bin or wormery they are offered at heavily reduced prices by most councils.
Mulches are spread over the soil surface and are essential in a dry and low maintenance garden. They keep moisture in, weeds down and protect shallow rooted plants from frost damage. Inorganic mulches such as gravel are brilliant for keeping moisture in and can be decorative. Organic mulches are applied every year and as the worms drag the organic matter they break up the soil and making it water retentive and free draining, especially important on clay soils or sandy soils.
In cities it is particularly beneficial to plant for all seasons as it keeps us tuned into natural cycles and provides nutrition for wildlife at times of year when food is scarce.
There is something quintessentially English about the lawn and it obviously plays an important role in providing safe recreational spaces within gardens. However, they are the most labour intensive part of the maintenance of any garden so consideration needs to be given to the proportion of lawn in your garden, and ideally should be kept to a minimum. Ecologically they are a monoculture (lacks biodiversity) that requires the use of machinery and often chemicals to keep them in good condition. Old lawnmowers pump in an hour the equivalent Co2 of a 100mile journey in a car. Electric mowers, powered by a renewable energy firm, would be better.
More than any other structure in a garden, trees are the most natural, elegant and beneficial. A single oak tree can support over a thousand different species and up to a million other organisms. A shelter belt of evergreen and deciduous trees can be used to reduce heating bills in the winter and keep your house cooler in the summer. Production of plants can be energy intensive and a bought tree can take 3-7 years to become carbon neutral in it's own right. The payback will be more effective if you choose a moderately fast growing and long lasting tree.
Green roofs and walls
These are brilliant ways of recovering previously lost green space whilst at the same time reducing heating bills and cooling buildings in summer. The methods and technology are constantly improving and design-wise you can achieve some very exciting things. Green walls, whether climbers or a whole wall of individual plants in pockets grown hydroponically are incredibly efficient at cleaning the air, and should be considered growing inside office buildings as well as out. Green roofs typically are covered with sedums or grass but there are other many alternatives to explore.
Pots and planters
Pots and planters dry out quickly and need a watchful eye. Always add a gravel mulch and use clay and volcanic rock products such as LECA and Perlite in pots as these hold on to water for longer whilst still keeping the soil loose. Glazed pots lose less water and wooden planters shield plants from the worst of the cold and heat.