Types of Natural Garden Fertilizers

Ground Rock Dusts

These are very slow-acting sources of fertility, but the most natural and long lasting and very good for revitalising worked-out soil.

seaweed meal - types of natural garden fertilizers Clay soils contain plenty of these ingredients in already finely divided form, so rock dusts are more use to those on poor sandy soils. Although rock dust is almost insoluble, if it is ground very finely water can act on an immense surface area to dissolve just a little. The plants can remove this from the soil solution, which then allows more to dissolve. The same huge area is also available for colonisation by microscopic life which starts to eat the rock dust and convert the surface material into biological mass.

So, by adding rock dusts rich in, say, potassium, we make more available to the plants, but only if our soils are moist and alive and teeming with the right microlife to be able to make use of it. Thus some rock dust can be added to the compost heap to make it bulk-up the right microbes. These will then inoculate the soil and make it more able to utilise the bulk of the dusts, applied more directly at a later date.

Most dusts can be applied any time, but winter is convenient. Choose a still day so that it doesn’t blow away and let light rain wash it in, or rake it in by hand. Never inhale rock dust. Some rock dusts are now supplied compounded to make them temporarily more granular and easier to handle.

Lime is commonly used on grass swards and on the vegetable patch. In a rotation, it is usually applied with peas and beans before or with brassicas, but never just before potatoes. It is the main source of calcium and in a form that can react chemically with acids and stronger alkalis in the soil; thus it is said to sweeten and improve most soils. Garden lime is ground chalk, builders’ and slaked lime is much stronger and not for garden use. Dolomitic lime is from rocks that also contain magnesium and so is doubly useful. Calcified seaweed is the best form of lime to apply because it contains all trace elements and so encourages healthy expansion of the microlife populations and is valuable added to compost heaps. It also has some use as a general-purpose fertiliser, except for lime-hating plants, and is especially beneficial for tough turf, brassicas, legumes and stone fruits.

Ground rock potash is rich in potassium which promotes flowering, fruiting and disease resistance. Especially needed on light soils and in wet areas. It is always appreciated by gooseberries and culinary apples. Apply it at any time.

Ground rock phosphate is rich in phosphorus which encourages healthy roots. It is useful for restoring healthy life to abused, over-acid soils and soils in wet areas. Mix it into the compost heap or the soil at any time. It is especially good for strawberries.

Ground rock basalt and granite may also be usefully added to any soil. These are rocks containing a range of minerals, so they encourage many micro-organisms. Their use is claimed to revitalise exhausted soils almost single-handedly.

Other Dusts and Garden Fertilizer Meals

The following are also worth trying; I have had good results with all of them.

Wood ashes are a very rich source of potash, but this is soluble and leaches out. Apply wood ashes to the soil immediately around growing crops, especially fruit and onions where it will encourage ripening and disease protection. Wood ashes should be sprinkled on the surface and raked in or mixed with their compost or planting soil.

Soot from fires (burning no plastic) contains some value as a fertilizer once mellowed with age, but is especially useful for darkening the soil surface, thereby improving its warming. Sprinkle aged soot on the surface of the soil after rain around early crops, such as asparagus and do not disturb.

Cocoa husks – I have been impressed by this nitrogenous waste. It is an expensive mulch, but a good binding agent with others and I’ve found the finely ground form useful in potting composts. It smells lovely to start with.

Seaweed meal contains a wide range of trace elements and significant nitrogen and potassium, but is a bit short of phosphate — add bonemeal or ground rock phosphate for balance. Organically, naturally and ecologically this is the best nitrogenous fertiliser and soil stimulator, and it is also a very good compost activator. Made from a very renewable resource seaweed meal is more pleasant to handle than blood, fish and bone meal for use as a general-purpose feed and is best raked in during spring.

Garden Foliar Sprays

For abundant and healthy leaf growth, try one of these sprays.

Seaweed solution – This is not so much a fertiliser as a catalyst or vitamin ‘injection’. Although sprayed on as a foliar feed only in very dilute solution, the effect on plants is rapid and marked. They take on a darker, healthier colour and are better at resisting both pests and diseases. Seaweed solution similarly stimulates the soil microlife, and is probably the most effective way of improving their variety and number. I spray the soil and every living thing in sight once a month from early spring. It can be diluted down and watered on as a liquid feed, but is better when combined with a cheaper source of nitrogen such as comfrey or borage liquid.

Equisetum tea – This is made from the dried plant and boiling water, then sprayed as a foliar feed when cool and diluted. It is high in silica which is believed to give plants more resistance to pests and diseases.

Garden Liquid Feeds

Plants confined in containers have a very restricted root run and cannot reach further afield for nutrients. Top dressing and repotting are possible solutions, but often we resort to feeding them nutrients each time they are watered. This seems at odds with the organic desire to avoid soluble fertilisers. But we are talking about plants in pots, not the soil, so we cannot apply the same rule. However, we should still follow the philosophy, only using feeds in a very dilute form, similar to normal soil-solution strength. The weaker the better, applied little and often — and never if the plants are growing slowly or under stress.

Unfortunately, all organic liquid feeds have a fairly strong and unpleasant smell, but this disappears when they are absorbed into the compost. Although these feeds are for plants with restricted root runs, they may be used with utmost moderation on hungry plants in the open, such as tomatoes or sweet corn, and to bring on spring greens in cold years.

Comfrey liquid – Comfrey leaves are collected, packed into a container, activated with a little personal liquid waste, weighed down and covered in water. They soon rot to form a black soup that smells horrible, but watered down to a pale straw colour, makes a well-balanced tomato (and other plant) feed which has considerable potassium as well as nitrogen. The concentrated soup can also be added to potting composts for added fertility.

Stinging nettle liquid – This is made and used in the same way as comfrey liquid and is claimed also to make plants more resistant to disease and pests, especially if diluted and sprayed on.

Borage liquid – Made as for comfrey. I have found this produces a highly nitrogenous concentrate that is worth trying for the hungriest feeders, such as melons and brassicas.

Dung bag tea – Sacks of manure were once hung in waterbutts to produce a dilute feed. The resultant soup is obviously variable depending on the dung used; it can be effective, but is nastier than other options.

Fish emulsion – This very rich source of nutrients is especially effective mixed with seaweed solution for use as a liquid feed.

Personal liquid waste – Call it what you will, this is sterile at source, rich in nitrogen and with significant potassium and other nutrients. When it is fresh, it can be diluted down twenty or forty to one and makes an excellent feed, especially for citrus. Don’t throw any away: save it all up and use it on the compost heap.

04. January 2011 by admin
Categories: Fertilizers | Tags: , | Comments Off on Types of Natural Garden Fertilizers


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