Please note that online plant orders are currently unavailable. Learn more.

Please note that online plant orders are currently unavailable. Learn more.

Organic gardening – growing your own fertility

Sharing a gardener’s perspective on building fertility the organic way.

Julian Blackhirst, Head gardener at The Garden of St Erth delves into organic gardening.

As the main growing season draws to a close, much of the biological activity retreats under the surface of the soil for the cooler months, reinvigorating the soil and building up fertility for the following spring. Soil life, organic matter and nutrients are drawn down into the soil, turning fallen leaves and debris from the summer’s growth into rich humus.

Making black gold

Tidying up our spent summer crops provides an abundance of material for the compost heap.  The success of our gardens depends on a good supply of compost, made in autumn and left over winter to decompose.

There are many different approaches to making good compost and sometimes advice on the topic can leave the gardener baffled and believing the process is beyond their capability.  Complicated formulas, ratios and lists of ingredients turn the art of compost making into a dogmatic scientific process, which even the most experienced gardeners can find hard to follow.

In fact, constructing a successful compost, whether in a free-standing heap or a compost bin, is very easy and forgiving, provided you have patience and follow a few simple guidelines.  All seasoned gardeners know that good homemade compost is the ‘black gold’ of the garden.

When constructing our compost heaps at The Garden of St Erth, we include any organic material we can find.  From fallen leaves to vegetable scraps, manure, weeds and crop residues, whatever we have available goes into the compost heap.  Provided there is a diverse range of different material, it will decompose into beautiful compost eventually.

While some consideration needs to be given to ensuring there is a mix of green (nitrogenous) material and brown (carboniferous) ingredients, there is a lot of leeway here and most mixed garden waste will have a sufficient mix for composting.  A small amount of garden soil or, better still, old compost added throughout the heap, will help moderate its decomposition and inoculate it with healthy microbes and bacteria.

Perhaps most importantly we ensure that each layer of the compost is watered and that the heap remains evenly moist.  Our compost is covered with a thick layer of straw to protect it from the elements.  It is ready to use when the original ingredients in the compost are no longer recognisable.  If all has gone well it should smell earthy and sweet and be teeming with worms.

Winter crops and green manures

While the soil can be a little depleted after a summer crop of vegetables, there is often enough fertility left in the soil to plant a lighter-feeding crop like garlic, carrots or (when time permits) sowing a selection of winter greens like pak choy, spinach or brassicas.

In our cold St Erth climate, planting early varieties of garlic in mid autumn allows us to harvest it the following November, so it doesn’t take up precious space in early summer.  Importantly, winter crops must be sown by the end of March here to put on good growth before the cold weather sets in.

In garden beds that are not being used over winter, sowing a green manure crop is a useful way of recycling unused nutrients and adding organic matter to the soil.  Crops like oats, vetch, mustards and clovers can send their roots down well over a metre into the soil, adding structure, carbon and drawing life from depths we would not be able to cultivate manually.  A mixture of cereals, legumes and tap-rooted mustards mimic nature’s natural grassland and pasture ecosystems.  Each different species accumulates a different rangeof nutrients from the subsoil, with legumes fixing nitrogen from the air as well.

Soil amendments like rockdust, lime and organic fertilisers can be applied directly to green manure crops, increasing growth and making nutrients available to subsequent crops once the green manure has been incorporated into the soil and decomposed.

In order to get the most out of our green manure crops, we leave them until they are just beginning to flower, then dig them in, usually in late winter.  At this point legumes will have fixed nitrogen into the soil and the green manure will provide maximum bulk organic matter to the soil.

Incorporating the green manure is made much easier by chopping it up first, either with garden shears, a whipper snipper or mower.  Once slashed, we can then lightly turn over the soil with a garden fork, burying as much material as possible and avoiding doing too much damage to the beautiful soil structure the green manure has created.  Within 4–6 weeks the green manure has decomposed, leaving a fertile soil that is teeming with life and ready for spring and summer planting.

 Slash large green manure crops with a whipper snipper before turning in the foliage.

Once your green manure has been slashed, it’s time to ‘dig it in’.

Composting is easy and forgiving, provided patience and a few simple guidelines are followed.

Good homemade compost is, as all seasoned gardeners know, the ‘black gold’ of the garden.

More

4.7 million Australian households are growing their own food

Our new Seed Manager was planting seeds as a child – that’s over 20 years of experience

Australia, where bird song began

Tim Sansom discusses Tim Low's new book

Bees and Colony Collapse

Jim Sansom tells us why the collapse of bee colonies is a huge threat to our food supplies

Bees Under Threat

Clive Blazey explains the largest ideas presented by bee keeper and BBC presenter Bill Turnbull

Biochar Explained

There’s been a lot of talk about Biochar, but what is it? How is it made? And what does it do?

Biodiversity in the garden

The benefits of encouraging a diverse ecosystem in your garden

Bringing carbon down to earth

Clive Blazey talks about sequestering carbon.

Creating the world we want, rather than fighting the world we reject

David Holmgren recalls his first meeting with Bill Mollison

Diggers explains how we make our own soil

Diggers explains how we make our own soil

Five Plants That Could Save The World

Tim Entwisle tells us how plants may provide the solutions to pollution and resource shortages

Fungi and Soil Creation

Botanic Gardens Director Stephen Forbes explains the role of fungi in creating soil

Gardening in a changing climate

Diggers former head gardener, Simon Rickard, shares the lessons learnt after a decade gardening in increasingly fluctuating conditions.

Gardening is the key to reducing Waste

Marcelle Swanson explains how to move away from plastics and improve our health

Giant Miscanthus

Tim Sansom explains how Giant Miscanthus can build organic carbon in backyards

Inspired by Diggers - 20 years ago!

Tim Sansom takes a tour of Joost Bakker’s Future Food System house

Manuka honey: is it a food or a medicine?

Penny Blazey reviews the history of this renowned honey

Monsanto's glyphosate

Graeme Sait assesses the ‘SAFE’ glyphosate spin to increase chemical usage

Organic gardening not just for food

Bill Bampton talks about creating garden beauty without petrochemicals

Q&A - How Carbon Creates Soils

World organic expert Dr. Christine Jones talks about the life-giving link between carbon and healthy topsoil

Reduce waste this holiday season

Join Erin Rhoads, the Rogue Ginger and waste-free advocate for some tips on waste reduction this festive season.

Save Water By Growing Your Own

Clive Blazey explains how you can save water by growing your own food at home

The Cape - Growing food in the heart of this sustainable community

Tim Sansom discovers a housing development making a real difference.

The difference between animal manures

Not all manures are equal, some are actually better than others.

The Future of Food

English author Colin Tudge explains how corporates and government threaten gardening and horticulture

The Soil Food Web

Hugh Hunkin explains how our lives depend on microscopic creatures

There Are No Jobs On A Dead Planet

An edited transcript from Kumi Naidoo's 2014 TED talk "Contagious courage, a billion individual acts"

Trees Are Vital For Cooling Our Cities

Bill Bampton explains why tree planting needs to start on a massive scale

Trees for Shade

Clive Blazey explains why shade canopy is vital in tree selections

Watering tips for gardens

Here are Diggers top tips to help Aussie Gardeners reduce their water consumption.

Why climate change threatens our biological systems

Clive Blazey reports on Tim Flannery's lecture on behalf of the Climate Commission

Why Diggers annual trials are so important

Our new Seed Manager explains the trial process at Diggers

Why do we import food?

Asks food writer Cherry Ripe

Why the collapse of bees is so serious

Fiona Chambers explains what Diggers members can do to help

Without trees we cannot inhabit the Earth

Bill Mollison's legacy foretells our climate crisis
Back To Top
Member Exclusives
2022 Gardening Diary and Calendar Combo
2022 Gardening Diary and Calendar Combo
BOOKS: ADIAC22
2022 Gardening Diary & Calendar Combo The complete garden combo for 2022! The beautifully illustrated Diggers Club Diary features a week to a page, seeds to sow each month, blank pages for seasonal observations, and handy pockets for your seed packets and plant labels, while The Diggers Calendar showcases stunning garden photography to inspire y...
Member $35.00
Checking stock, please wait..
A YEAR OF VEGIES - SEED BOX
A YEAR OF VEGIES - SEED BOX
SEEDS: S921
18 SEED PACKETS: The gift that keeps on giving for a year. This collection will guarantee 12 months of heirloom veges. The recipient will receive seeds for each season ensuring a supply of heirloom vegetables. The pack contains a total of 18 packets of vegetables seeds (Beetroot, Bean, Broccoli, Carrot, Cauliflower, Lettuce, Onion, Pea, Silverbe...
Member $59.95
Checking stock, please wait..
2 year membership + Garden Calendar and 2 Seed Packets
2 year membership + Garden Calendar and 2 Seed Packets
Membership: MNE2CA2
Join the club and receive an exclusive gift, valued at $30. A stunning calendar featuring key dates, a guide to which seeds to sow each month and plenty of space to add your own events. Plus two free packets of some popular seeds – Tomato 'Black Cherry' and Lettuce Heirloom Mix.
Member $79.00
Non-Member $79.00
Checking stock, please wait..