Organic Fertiliser Guide
Nettles, Comfrey, Seaweed and Cow Manure can all be used to make effective organic fertilisers for the garden. As chemical products become less widely available, many gardeners are returning to traditional organic feeding methods that are inexpensive, sustainable and easy to prepare at home.
Equipment Required
- Black bin bags
- Garden fork or rake
- 10-litre bucket
- Old pair of nylon tights or stockings
- Wheelbarrow
- Dark-coloured plastic bottle
- Labels and string
Nettle Fertiliser
Fresh nettles make an excellent nitrogen-rich liquid feed. Fill a black bin bag halfway with freshly cut nettles and add approximately 1 litre of rainwater. Continue filling the bag until it is around three-quarters full, then tie the top securely.
Use a garden fork to make several small holes around the sides of the bag to allow airflow. Place the bag in a sunny location against a wall, fence or hedge.
After approximately two months, the nettles will have broken down into a concentrated liquid fertiliser. Stretch old nylon tights over a bucket and secure them to create a sieve. Carefully drain the liquid through the nylon into the bucket and squeeze the bag gently to extract as much liquid as possible.
Store the concentrate in a dark bottle and clearly label it with the preparation date.
Application Rate
- 2 tablespoons of concentrate per 10 litres of water every 14 days, or
- 1 tablespoon per 10 litres of water once per week.
Apply during active growth from May to August, preferably in the late afternoon or early evening.
Comfrey Fertiliser
Comfrey fertiliser is prepared using exactly the same method as nettle fertiliser. It provides a valuable source of potassium and is particularly useful for flowering plants and fruit crops.
Seaweed Fertiliser
Before use, thoroughly wash collected seaweed to remove excess salt and sand. Allow rainfall to rinse the seaweed naturally or wash it with a hose.
Once cleaned, place the seaweed in a black bin bag and prepare it using the same method described for nettles.
Application Rate
Seaweed concentrate is stronger than nettle or comfrey feed. Dilute at a rate of 1 tablespoon per 10 litres of water and apply every 14 days during the growing season.
Cow Manure Fertiliser
Fresh cow manure from straw-fed or hay-fed cattle can be used to create a nutrient-rich liquid fertiliser. Avoid manure from silage-fed cattle, as it can be excessively strong and may damage plants.
Equipment Required
- Hessian sack
- Concrete block or large stone
- Strong rope or twine
- Metal S-hook
- Water butt with lid
- Protective gloves
Place a stone or concrete block into the hessian sack and fill it three-quarters full with fresh manure. Secure the sack with rope and suspend it inside a water butt so that it hangs approximately one-quarter of the way up from the bottom.
Fill the water butt with rainwater and secure the lid. Leave for two weeks in a sunny position.
Before each use, lift and lower the sack several times to agitate the liquid.
Application Rate
Dilute 570ml (1 pint) of concentrate in 10 litres of water and apply every 14 days from May to August.
This feed is naturally high in potash and is particularly beneficial for tomatoes and other fruiting crops.
Feeding Tomatoes
When feeding tomatoes, apply fertiliser to the soil around the plant rather than directly against the stem. Tomatoes develop shallow feeding roots and deeper water-absorbing roots.
A useful technique is to sink a 1-litre flower pot into the soil near the plant. Water can then be poured directly into the pot, helping moisture reach the deeper roots efficiently.
During warm weather, a mature tomato plant may require up to 10 litres of water per day.
Wood ash can also be incorporated into the soil before planting at a rate of one handful per square metre to increase potassium levels.