A short guide to their use: At the end of the page are more scientific details of specific fertilisers.
All are available loose and at highly competitive prices to members of the Society from the Store, The Pleasance, Dover House Road every Sunday morning, 10.00 am to 12 noon.
Seaweed
Available as a LIQUID feed or in a DRIED form.
An organic fertiliser and soil improver which provides useful sources of potassium, magnesium and trace elements.
A real all-rounder. Will give you healthy plants that resist disease and pests. Can be forked (or watered) in lightly any time or year, but optimum times are Spring and Autumn.
The dried seaweed is also an excellent additive to compost.
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Bone Meal
An organic fertiliser which supplies phosphate for good root development and some nitrogen for growth and dark green foliage.
Bone meal acts slowly and can be applied under the roots when planting out or forked in before planting over a larger area. Water in if dry.
Should not be used on acid loving plants such as blueberries.
Good for root development of roses, trees and woody shrubs.
Use 100-125 grams per sq. metre
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Fish, blood and bone
An organic all round fertiliser which supplies a good balance of phosphate for root development, nitrogen for growth and dark green foliage and potassium for flower/fruit production.
Fish, blood and bone is faster acting than just bone meal. It is best used to improve soil before planting out or when seed sowing. It is also good as a top dressing during growth.
It is a good soil improver if land has not been cared for.
Use 50-200 grams per sq. metre
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Growmore
An inorganic fertiliser which is made up of equal parts of nitrogen, phosphate and potash. It is an all-purpose fertiliser which promotes good root development, general growth, production of fruits and flowers and helps with resistance to frost and fungal diseases.
Growmore can be used at any time of the year.
Use 50-125 grams per sq. metre.
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Hydrated lime
Although inorganic, lime is used widely to neutralise acid soils and break up heavy clay. It also supplies calcium which improves plant structure increasing resistance to wind, hail, insects and other physical damage.
Fork into soil in the autumn in areas where you plan to grow brassicas and other alkaline loving plants such as spinach or onions.
Brassicas will benefit from resistance to club root fungus.
Do not dig in at the same time as manure or compost as they will counter act each other.
Do not use on a windy day as it will damage nearby plants. Water in well.
Use 0.5 to 1 kg per sq. metre
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Sulphate of ammonia
An inorganic quick acting fertiliser which contains a high amount of nitrogen which is used for rapid growth of leafy vegetables such as cabbages and lettuces.
Apply between April and September sprinkling evenly between rows.
Can be used in the autumn to help leeks recover from leek moth.
Use 25 grams per sq. metre
Can also be used on compost heaps instead of Garotta to accelerate decomposition. Dissolve 1oz in 2 gallons of water and pour over compost after each 6” of matter.
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Sulphate of potash
An inorganic fertiliser which has a high potash content.
Potash is essential for production of flowers and fruits and is therefore good for tomatoes, fruit bushes and fruit trees.
Can be used as either a base or top dressing and is best used late winter and early spring. It can be dissolved in water and used as a liquid feed (1oz in 2 gallons). Be careful not to put directly onto foliage.
Use 25 grams per sq. metre
Make your own
Wood ash supplies organic potash but is mostly calcium carbonate. Potassium, phosphorus and many trace elements are also present. This can be dug in as a base or top dressing or in larger quantities as a soil neutraliser instead of lime.
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Superphosphate
An inorganic fertiliser supplying a concentrated amount of phosphates to improve root development and help the quick establishment of young and/or recently moved plants.
Can be used all year round as a base dressing before planting or sowing as well as a top dressing for established plants.
Peas, onions and root crops benefit from this fertiliser.
Water in well and be careful not to get onto foliage.
Superphosphate will kill your worms.
Use 50-125 grams per sq. metre
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Poultry Manure Pellets
An organic fertiliser which contains nitrogen for green leafy growth but smaller amounts of phosphorus and potassium and is therefore not for all-round use.
The nutrients are released slowly once the soil warms up.
Improves soil structure by adding humus and soil moisture retention
Because of its alkaline nature poultry manure should not be used on acid loving plants such as blueberries.
Add poultry manure to your compost heap to help the acceleration of decomposition.
Use 150 – 200 grams per sq. metre
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Volcanic Rock Dust
An organic fertiliser composed of slow release minerals and trace elements which replace the nutrients and microorganisms in the soil that have been depleted due to many years of horticulture.
Rock dust will increase water retention of the soil, increases resistance to pests and diseases and encourages worms.
The best time to apply is over the winter but it can be used all year round. Avoid applying on a windy day.
Rock dust can be used alongside other soil conditioners and manures. If using lime do not mix at the same time – leave a few weeks between each.
Use
In the first year fork in up to 2kg per sq. metre and then in following years 0.5 to 1kg per sq. metre.
Can be added to compost heaps to accelerate decomposition – 3-5mm every 13cm of matter.
For seeds or potting on – use 1 part rock dust to 4 parts all-purpose compost.
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Organic fertilisers are those that originate from living organisms (plants or animals). They release nutrients slowly and may also improve soil texture. They contain trace elements as well as major nutrients but are unpredictable in what they release. If bought, they may be expensive if they are bulky and weigh heavily, but the cheapest source is always your own compost heap. They maintain long-term soil fertility and are used to prepare soil for planting shrubs and slow-growing plants. Examples include: bone meal; fish , blood and bone; horse manure and Country Natural Compost.
Inorganic fertilisers are exact in their contents and come either from quarried materials e.g. rock phosphate, limestone and Epsom salts (magnesium sulphate) or are manufactured chemically e.g. Growmore, nitrochalk and superphosphates. (The latter are not acceptable to strict organic gardeners.) Inorganic fertilisers can quickly supply a particular deficiency e.g. ammonium sulphate will supply nitrogen. Proprietary fertilisers have different N:P:K ratios (see below) for different plants e.g Cactus fertiliser has a ratio of 8:34:32. The disadvantages of inorganic fertilisers are that they may leach (drain) rapidly from soil after rain, and can damage plants if applied too liberally.
Base dressings are dug into the soil at root depth when preparing it for planting. All slow-release organic fertilisers are suitable, as are the newer (expensive) inorganic fertilisers in a resin coating e.g. Osmacote and Chempak’s Summerlong.
Top dressings are applied on the surface around established plants. They are best applied under a mulch or watered in thoroughly to distribute the fertiliser equally.
Major Plant Requirements (N:P:K)
- Nitrogen (N): essential for growth and dark green foliage; apply as base or top dressing; particularly to young plants and sparingly to mature plants
- Phosphate (P2O5): essential for good root development; promotes ripening of fruits and seeds; apply as base dressing or top dressing forked in to reach the roots
- Potash (K2O): essential for production of flowers and fruits; promotes healthy growth and resistance to frost and fungal diseases; apply as base or top dressing; slow to leach away and therefore apply at any time of year
As well as a large number of commonly used garden products (e.g. seed and potting composts, Garotta, lawn feed, insecticides, weed killers, slug pellets, etc.), the Store stocks the following loose fertilisers.
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Bone meal: organic fertiliser supplying phosphate and some nitrogen; acts slowly; do not use on acid-loving plants (use 100-125 g per sq m or 3-4 oz per sq yd)
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Fish, blood and bone meal: as above but quicker acting with more nitrogen; apply before planting or sowing seeds or as a top dressing during growth (use 50-200 g per sq m or 2-7 oz per sq yd)
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Growmore: (N:P:K = 7:7:7) suitable inorganic all-purpose fertiliser (use 50-125 g per sq m or 2-4 oz per sq yd)
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Lime: inorganic; although supplying calcium its importance is in neutralising soil acidity; in turning soils alkaline it protects brassicas against club root fungus; it improves the soil texture of heavy clays
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Nitrochalk: quick-acting inorganic nitrogenous fertiliser containing lime and therefore useful to combat acidity; use as top dressing in summer but avoid excess (use about 25 g per sq m or ½-1 oz per sq yd)
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Rose fertiliser: made to Tonk’s formula specifically for roses (use 50-125 g per sq m or 2-4 oz per sq yd)
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Sulphate of ammonia: quick-acting inorganic nitrogenous fertiliser; boosts growth of leafy vegetables (cabbages, lettuces, etc.) (use about 25 g per sq m or ½-1 oz per sq yd)
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Sulphate of potash: inorganic fertiliser supplying potash (see over page); essential for tomatoes (use about 25 g per sq m or ½-1 oz per sq yd)
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Superphosphate of lime: neutral inorganic fertiliser supplying phosphate (see over page) (use 50-125 g per sq m or 2-4 oz per sq yd)
A small 150 g yogurt carton holds about 200g (7oz) fertiliser. NB Chemical fertilisers should always be used with great care