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From preserving soil during construction to building walls for plants to grow up while materials and machinery are on site, the Royal Horticultural Society offers a number of suggestions for green-fingered self-builders. This article presents the four key considerations to take into account when constructing a self-sufficient garden.
Collect water
Water is obviously essential for plant growth, so it pays to store and collect what you can. Plants need the most water in hot, dry and windy weather, which is usually when water companies are least able to meet demand.
Less than 3% of the annual water consumption of an average household is estimated to be from garden use, but at peak demand as much as 70% of water supplied may be used in gardens. This surge in demand can lead to water companies being forced to deplete groundwater and streams, which can cause serious environmental damage as well as raising the cost of water for consumers. Gardeners should therefore use mains water as sparingly as they can.
24,000 litres could be collected from the roof each year. However, most water falls in winter and would have to be stored for use in summer. There are about 18 weeks from May until September when plants’ needs exceed rainfall. At first, the shortfall is met from soil reserves, but these can peter out by July, leading to about six weeks when watering is needed. Even tiny gardens and patios can be used to collect and store rainwater, which may help the gardener get through hosepipe and sprinkler bans.
Rainwater can be collected from the roofs of homes, garages, greenhouses and other garden structures as long as they have gutters and a drain pipe.
Water butts are designed to collect water from either open or closed drain pipes. Closed drain pipes can be easily tapped into with a rain water diverter kit. Local councils and DIY stores are good places to purchase basic plastic water butts. It is easier to access the water if the butt has a tap at the base and sits on a stand, either ready-made or improvised with a pile of bricks. More expensive butts moulded to look like beehives or terracotta urns are an attractive option, as are recycled wooden barrels.
As climatic change models suggest an increasing proportion of rain will fall in winter, it may become cost effective to build-in rainwater storage when constructing new homes. This usually involves sinking a large tank somewhere in the garden, pumping water out for use in the garden or for domestic tasks such as flushing toilets. However, the more pumps and piping that is required, the greater the cost and carbon footprint of such schemes.
Drainage
Good drainage is crucial for growing many garden plants. Installing drainage is a major undertaking, but on wet soils, it is one of the most helpful things a gardener can do to improve growing conditions.
Drainage is important for gardens, but not every garden will need it installed. If you are considering installing drainage, think about where the water will go. Ditches, streams or soakaways – deep holes filled with rubble that penetrate to porous rocks – are all suitable. Local byelaws usually prohibit adding drainage water from gardens to sewers or storm drains.
Where there is nowhere for water to go, consider growing in raised beds, or perhaps consider a bog-style garden. Installing drainage involves burying porous pipes at about 45cm deep. This is very disruptive and is difficult to accomplish when the soil is wet. The best time for this type of ground work is from late summer until early winter when ground conditions are usually driest.
Before going ahead and installing a drainage system, consider if normal cultivation methods might be all you need to improve drainage. This is often the case for old, established beds and borders that may have become compacted over time. In this case, consider digging the beds and adding organic matter.
Be sure to avoid cutting pipes and cables when trench digging. It can be difficult to lay pipes with sufficient enough fall for water to drain away. In this case consider installing electric pumps and float switches.
Another common problem is finding a place for water to go. It may be possible to work with neighbours or other local landowners to find an outfall for surplus water. It is rather anti-social to dump surplus water at the lower end of your property to flood neighbours gardens. However in some circumstances a seasonal pond or swale might be the solution.
Raise the bed
Raised beds are a great way of growing a wide range of plants, and are particularly popular for growing fruit and vegetables. They are a good way of boosting drainage and can be used to introduce a different soil type to your garden. Raised beds are also a useful way to garden if you have restricted mobility, as they reduce the need to bend.
You can grow almost any plants in raised beds. Although raised beds can be built at any time, most gardeners find it convenient to build them in winter, as long as the soil is not too wet or frozen. It’s also a good idea to create beds while machinery and materials for your build are still on site.
When building raised beds, the following points need to be considered:
• Plants in raised beds can suffer more quickly and more severely from drought due to improved drainage, so keep an eye on watering needs.
• Modern wood treatments do not contain potentially harmful heavy metals, so are safe to use. If in doubt, line the inside of the bed with polythene.
• New railway sleepers may contain creosote that should not be used where skin contact is a possibility. Creosote is thought to have dissipated from older sleepers, and these may be used without concern about skin contact.
Greenhouses
Greenhouses are invaluable for creating a protected growing environment for tender plants and seedlings. However, there are many different kinds to choose from, so it is important to consider your growing requirements before buying one.
Growing under glass provides a protected environment ideal for raising seedlings, overwintering tender plants, growing crops such as tomatoes, or even cultivating plants that need protection year-round. Greenhouses allow the gardener to extend the growing season, sow plants earlier and provide the ideal place for rooting cuttings.
Ideally, greenhouses should be sited where they can receive uninterrupted sun throughout the day. Provide screening or shelter from cold northerly or easterly winds, which can keep temperatures low in spring and slow the growth of seedlings and young plants.
An east-west orientation will slightly extend light levels during winter. A north-south orientation for summer crops such as tomatoes, both sides receiving several hours’ sun from the east and the west. With this orientation, the end timbers will reduce the amount of sun reaching the house during the hottest midday period. Decide when you plan to use your greenhouse most, and orient it accordingly if you can.
Figs
Figs are large shrubs or small trees grown for their succulent fruit and beautiful architectural foliage. They thrive in the garden, in a container, in glasshouses or trained against a wall.
• Figs come from warm, Mediterranean climates and will thrive in a sunny and sheltered position with well-drained soil.
• Although figs can cope with dry conditions, drought can cause fruit to drop prematurely. Water plants regularly during the summer season, but do not give them too much or water them erratically while the fruit is ripening, as this may cause the fruit to split.
• Feed in early spring by spreading 70g of a balanced granular fertiliser over the ground, and cover with a thin layer of well-rotted manure. When the fruit appear, feed weekly with a high-potassium liquid plant food.
• Figs give the best quality and quantity of fruit when roots are restricted. For this reason they are well suited to container cultivation. Plant in a large, 30-38cm pot filled with gritty compost.
Apricots
Apricots are delicious fruit, packed with juice and delicate flavours – those grown in the garden and eaten straight from the tree are tastier than anything bought in a shop. Given their exotic image, they are not the tender treasures you may imagine. Many modern cultivars have been bred to crop reliably in cooler climates. They can be grown as fans, bushes or pyramid trees - there are even dwarf varieties for a pot on the patio. Apricots are self-fertile and crop with a single tree.
• Cover apricot trees with horticultural fleece, or clear polythene supported by bamboo canes, to protect the blossom from frost. The fleece or polythene must not touch the flowers. Remove this during the day to allow sunlight and pollinating insects to reach the plant.
• Hand-pollination increases yields, over several days – ideally around noon on a dry, sunny day – using a soft artist’s brush or a cotton wool bud. Lightly mist the tree with water to ensure that the pollen sticks but so the flowers dry out before dark.
• Heavy crops should be thinned to about 8-10.5cm apart when the fruits are the size of hazelnuts. Start by removing mis-shapen fruit and those growing towards the wall.
• Water newly-planted trees frequently as they establish in their first spring and summer, and before the onset of drought, when mature trees may need watering too. This is particularly important when the fruit starts to swell.
• Feed with granular fertiliser such as Growmore at 70g per m² in late February.
• Mulch around the rooting area with a 5cm layer of well-rotted manure, in March and early April.
