To dig or not to dig
Occasionally a soil needs to be dug e.g. to break up really hard compacted soils. Generally though, the best way to condition a soil so that it is friable and allows plant roots to penetrate, is to supply plenty of organic matter and encourage microbes, earthworms and other soil life to do the job for you.
No-dig and raised beds plentifully supplied with compost and mulch is the best organic option. These soil-friendly methods are also labour-saving in the long-term – no digging, less weeding, healthier plants so therefore less disease and pest control.
Begin preparation of previously uncultivated areas for spring planting during autumn/winter in warmer climates, late winter/early spring (as soon as soil begins to warm up) in cold areas.
Breaking in new ground – no dig
- Reduce weeds by hand-pulling, mowing, hoeing etc. Don’t worry about pulling all the roots – left in the soil to decompose they provide refuges, food and work for soil organisms and channels for air and moisture to penetrate.
- Leave weed trimmings on the bed or remove to the compost.
- Cover with a thin layer of organic mulch. Newspaper is OK – about one centimetre thick – making sure sheets overlap. Modern inks are relatively harmless and break down in a matter of days. You can also use corrugated cardboard (if from cartons make sure contents were residue free). The idea is to block light and so prevent weeds growing again.
- Top with mature or nearly mature compost. Compost that’s not completely mature still contains organisms responsible for breaking down organic matter. Using this with plenty of non-composted material – weeds, leaves, spent plants – is another way of introducing biological activity to the soil.
- Water well.
- Mulch with spoilt hay, or other available organic material – even old woollen rugs, blankets etc.
- Leave to settle for a few days before planting.
Using raised beds is an ancient technique used by gardeners in many cultures. The benefits include:
- Greater depth of soil gives better fertility especially on poor or difficult soils.
- There are better soil conditions e.g. drainage, warms up quicker.
- Encourages deep rooting so plants can be grown closer together.
There are several things to consider before placing and making raised beds. Many of these considerations apply to any garden design.
Plan bed placing carefully together with paths and access. You may start with just one or two beds, but plan for more. Use garden space economically, minimising paths – without skimping – and maximising growing areas.
Try to get this right first time – it’s a chore to resize a raised bed. It is critical no one walks on the bed – the weight compacts the soil and undermines the reason for raising it – so size it accordingly.
- Width is the key to managing the bed without setting foot on it. Optimum width is two arm lengths – so you can reach the middle from either side.
- Length depends on personal preference and the site. But if the bed is too long, it’s tempting to step across instead of walking round.
- Round beds are good, though a bit more tricky to edge. They are great for really compact plantings, especially as plants tend to the round rather than rectangular shape. Decorative and feature planting is easier too.
- Spacing between beds must accommodate a wheelbarrow and allow you to crouch, carry buckets, watering cans etc.
- Beware of making beds too small. Soil is an ecosystem and doesn’t function well if isolated in too small compartments. Minimum size 1 metre square.
Edgings are not essential but do make it easier to retain the soil and to “top up” with extra material. They also allow for a flat rather than heaped working surface.
Edging materials are many and varied. In terms of economy make use of what’s immediately to hand e.g. stones, bricks, untreated timber. Garden centres carry a wide range but choose untreated materials. Toxic chemicals used to weather proof timber, for example, can leach into the ground contaminating soil and plants. Durable timbers like totara, some eucalypts, jarrah are sometimes available. Macrocarpa is useful but will eventually rot, needing to be replaced.
For really neat, weedfree paths, skim off the top layer of soil – put onto the raised bed – lay down plastic or weedmat and top up with bark, gravel, paving.
For a more natural look use pads of spoilt hay or shredded branches. Or sow a herb that withstands treading or a nitrogen rich ground cover such as Lucerne.
If building on uncultivated ground, make the foundation using the methods described above but filling with soil on top of the paper/cardboard layer. Fill with compost or soil from other parts of the garden if you have it.
Alternatively bring in good quality, screened top soil or compost and if necessary give it a boost with compost from a good organic source. It’s important to enliven the soil as quickly and as much as possible.
Permaculture (permanent agriculture) principles coincide with organic principles and set out very definite management principles. Zoning can help decide what goes where. Designed primarily for farms and large gardens, it may not always work on the small urban section, but can guide your thinking.
Zone 1 is nearest the house; everyday veges (salad and herbs) and short-season fruits e.g. strawberries; favourite flowers and shrubs (especially for cutting). Extend by using pots and other adaptable containers.
Zone 2 a bit further afield comprises main vegetable gardens, slower growing crops, possibly somewhere to raise plants, worm farm even a chicken coop.
Zone 3 is furthest away, requires least maintenance; fruit trees and service areas such as compost bins.
The ideal is to raise your own plants from seed or cuttings as much as possible. If raising plants from seed, try to buy from companies who promote organic and heirloom seeds.
You may want to save your own seed. This is fairly straightforward, but till you get the hang of it, start with simple crops like salad greens or tomatoes, pumpkins etc. Only open-pollinated plants will have viable seed. Hybrid varieties are crosses and are unlikely to be true to the plant you allowed to seed. Choose plants:
- That have stood up to the climate and environment
- That have the best flavour
- That are best suited to your purposes
- That have resisted pests and disease
Content from Organic Gardening – A Guide by Organic NZ, published by the Soil & Health Association.