Question 1

What is organic fertiliser?

Accepted Answer

Organic fertiliser holds its nutrients inside natural materials such as plant meals, seaweed and mined minerals, and soil organisms break those materials down before roots can take the nutrients up. A manufactured feed dissolves on contact and is available at once. Both end up supplying the same nutrient ions, but the organic route releases them gradually and leaves organic matter behind in the soil.

Question 2

What is organic fertiliser made of?

Accepted Answer

Organic fertiliser is made from milled plant meals such as alfalfa and rapeseed, from seaweed, and from mined minerals such as rock phosphate, polyhalite, gypsum and sulphate of potash. Nitrogen usually comes from protein-rich meals or a concentrated protein extract, phosphorus from rock phosphate and calcined meals, and potassium from sulphate of potash or polyhalite. A finished blend combines fifteen to eighteen of these so that one bag supplies the major nutrients along with calcium, magnesium, sulphur and trace elements.

Question 3

What does organic fertiliser do?

Accepted Answer

Organic fertiliser supplies nitrogen, phosphorus and potassium along with calcium, magnesium, sulphur and trace elements, and releases them gradually as soil organisms break the material down. At the same time it adds organic matter, which improves soil structure and water holding and feeds the bacteria and fungi that do the releasing. A soluble feed does the first job faster and the second not at all.

Question 4

What are examples of organic fertilisers?

Accepted Answer

Common organic fertilisers include garden compost, well-rotted manure, leaf mould, seaweed, comfrey and nettle liquids, worm castings, milled meals such as alfalfa and rapeseed, and mined minerals such as rock phosphate, gypsum, polyhalite and sulphate of potash. They fall into four practical groups: bulky soil builders, slow-release meals and minerals, concentrated blends, and homemade liquids.

Question 5

What are the advantages and disadvantages of organic fertiliser?

Accepted Answer

The advantages of organic fertiliser are slow, steady release, a low risk of scorch, less leaching in heavy rain, and organic matter that improves soil structure over several seasons. The disadvantages are that it acts slowly, carries a lower and more variable analysis so you apply more by weight, costs more per unit of nutrient, and does very little in cold soil because release depends on soil organisms.

Question 6

Is organic fertiliser better for plants?

Accepted Answer

Not directly. Plants absorb nutrients as simple ions, and a root cannot distinguish a nitrate ion mineralised from organic material from one dissolved out of a manufactured salt. Organic feeding is better for the soil: it adds organic matter that improves structure, water holding and soil biology, and those improvements produce steadier growth over several seasons. The advantage is real but indirect.

Question 7

What is 4-4-4 organic fertiliser?

Accepted Answer

A 4-4-4 organic fertiliser carries 4% nitrogen, 4% phosphorus as P2O5 and 4% potassium as K2O. The three equal numbers make it a balanced general feed, suited to leafy vegetables, shrubs, trees and mixed beds where no single nutrient needs pushing. Because the analysis is modest and the nutrients release slowly, it is difficult to overdose.

Question 8

What is slow-release organic fertiliser?

Accepted Answer

Slow-release organic fertiliser holds its nutrients in natural materials that soil bacteria and fungi must break down before roots can take them up, so the feed is released gradually instead of dissolving all at once. Most granular organic feeds begin working within two to six weeks and continue for six to eight. The rate of release is set by soil temperature, moisture and texture, not by how much you applied.

Question 9

How long does organic fertiliser take to work?

Accepted Answer

Most granular organic fertilisers begin working within two to six weeks as soil organisms break them down, and continue feeding for six to eight weeks. Liquid feeds and concentrated protein extracts act faster, within one to two weeks. A soluble synthetic feed acts within days. All organic release slows as soil temperature falls and nearly stops below about 4 degrees Celsius.

Question 10

How do you use organic fertiliser?

Accepted Answer

Mix organic fertiliser into the soil or compost before planting, or scatter it on the surface around growing plants and water it in. Apply to moist soil rather than dry, keep granules off leaves and stems, and follow the rate printed on the pack. Rates vary widely between products because the analysis does, so a figure from one feed should never be carried across to another.

Question 11

How often should you apply organic fertiliser?

Accepted Answer

For most outdoor beds and borders, apply organic fertiliser every four to six weeks through the growing season. Pots and containers hold less soil and are watered more, so they need topping up every two to four weeks. Heavy feeders in peak summer sit at the shorter end. There is no need to feed in winter, when growth has stopped and release has nearly halted.

Question 12

What is the best organic fertiliser high in nitrogen?

Accepted Answer

The highest practical nitrogen in an organic feed comes from concentrated protein extracts, at around 13% nitrogen. Milled meals such as alfalfa and rapeseed carry 2 to 3%, seaweed meal under 2%, and garden compost well under 1%. Use a high-nitrogen feed for leafy crops, lawns and early growth, and ease off once flowering starts, because excess nitrogen produces soft growth at the expense of flower and fruit.

Question 13

What organic fertiliser is high in phosphorus?

Accepted Answer

Micronised rock phosphate is the highest natural phosphorus source at around 31% phosphorus, with roughly half its weight as calcium, but it releases over seasons rather than weeks. A finished high-phosphorus blend such as a 2-8-4 supplies 8% P2O5 in a form available within the season. Test before adding phosphorus, because many established UK garden soils already hold plenty and it is slow to leave once applied.

Question 14

What is the best organic fertiliser high in potassium?

Accepted Answer

Sulphate of potash is the highest organic potassium source at 50% K2O, chloride free and carrying about 18% sulphur. Polyhalite is a gentler alternative at 14% potassium, supplying calcium and magnesium alongside it. Comfrey liquid and wood ash supply potassium too but at low and variable levels, and wood ash also raises soil pH. Potassium demand peaks from flowering through fruiting.

Question 15

What is the best organic fertiliser for vegetables?

Accepted Answer

For a mixed vegetable plot, a balanced feed with a slight potassium lead such as a 4-5-6 covers most crops well. Leafy crops such as salads and brassicas do better on a more nitrogen-led feed, and fruiting crops such as tomatoes, chillies and strawberries do better on a potassium-led one from flowering onwards. Compost worked in before planting underpins all of it.

Question 16

What is the best organic fertiliser for roses and flowers?

Accepted Answer

Roses and flowering plants want enough nitrogen to build strong stems and plenty of potassium for flowering, with calcium and magnesium alongside. A balance around 5-3-5 covers both. Feed first in early spring as the buds break, work it lightly into the soil surface and water it in, then feed again after the first flush of flowers. Stop by late summer so soft growth is not pushed into autumn.

Question 17

What is the best organic fertiliser?

Accepted Answer

There is no single best organic fertiliser, because the right one depends on the job. Compost is best for building soil. A balanced blend such as a 4-4-4 is best for general growth across mixed planting. A potassium-led feed such as a 3-4-6 is best for fruiting crops from flowering onwards. A concentrated nitrogen feed is best for lawns and leafy crops. Choose by what the plant is doing rather than by the brand.

Question 18

What is the best natural fertiliser?

Accepted Answer

Compost and well-rotted manure are the best all-round natural fertilisers for building soil, because they add organic matter in quantity. For feeding through the season, seaweed supplies trace elements and alginates, comfrey liquid supplies potassium for fruit and flowers, and nettle liquid supplies nitrogen for leafy growth. Natural here means the material is used much as it is found, rather than manufactured as a soluble salt.

Question 19

What is the best source of organic fertiliser?

Accepted Answer

The best source of organic fertiliser is your own compost heap: it is free, it uses waste you already produce, and it adds organic matter that improves soil structure as well as supplying nutrients. Beyond that, well-rotted manure from a local source covers bulk soil improvement cheaply, and a bagged blend covers the concentrated feeding that compost cannot, provided you can read its full ingredient list.

Question 20

Which is the best organic fertiliser company?

Accepted Answer

Judge an organic fertiliser company on what it is willing to show you rather than on its marketing. Four checks sort most of the market: is every ingredient named on the label, are application rates published for beds and for pots, does the analysis go beyond the three headline numbers to include calcium, magnesium and sulphur, and are the claims specific enough to be tested. A company that hides any of the first three is telling you something.

Question 21

How do I feed my plants without chemicals?

Accepted Answer

Feed the soil with compost, leaf mould and well-rotted manure, which release nutrients gradually and improve structure at the same time, then top up growing plants with steeped liquid feeds made from seaweed meal, alfalfa pellets, comfrey or nettles. For pots and hungry crops that need more, a concentrated feed made from milled meals and mined minerals covers the demand without manufactured soluble salts.

Question 22

What is the best homemade plant food?

Accepted Answer

Comfrey liquid is the best-known homemade plant food for fruit and flowers because it is potassium led. Nettle liquid suits leafy growth because it is nitrogen led. Compost is the best homemade soil feed. Seaweed meal and alfalfa pellets can also be steeped at home for a quicker-acting drench. Coffee grounds, banana skins and eggshells break down too slowly to work as direct feeds and are better added to the compost heap.

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