Thanks for taking your time to read our information on the various types of fertlisers that are available in the UK. You may also see this word spelled as fertlizer which is of course the USA spelling. Either spelling refers to exactly the same product.
In the main, fertlisers are usually associated with farmers. They are however used by many gardeners up and down the United Kingdom. We have written this as a beginners guide or introduction to the use of fertlisers for your gardens.
Fertlisers are used to improve plant growth and also to increase yields. They are available in different forms such as a powder, liquid, granules or pellets. They are a concentrated form of plant nutrients and very popular with gardeners for healthy growth.
What are the two main types of fertlisers?
Fertilisers will either be organic or inorganic
- Organic Fertlisers- These work well in light, sandy or chalky soil. They are more expensive than inorganic fertlisers. They do not release their nitrogen until they get broken down by the soil. The rate at which the nitrogen is released will depend on the exact soil conditions. In the UK, during the Spring, Summer and early Autumn the soil is warm and so quite a lot of nitrogen is released. However in the late Autumn and Winter, when the soil is cold very little nitrogen is released. They include nutrients such as dried blood, horn, hoof and bonemeal.
- Inorganic Fertlisers - You will more commonly hear these referred to as "artificial" or "chemical" fertilisers. That is because they are actually manufactured and some of them are also mined. They are sold in what is called a soluble form which means they are broken down by rain or watering. They are not dependent on having the right soil conditions. These work very quickly and that is what makes them so popular. The disadvantage is that if over used or used incorrectly they may in fact scorch plants.
Plant growth is hugely improved if you have the right soil balance. Growth is always better if plants have access to nutrients such as nitrogen, potassium and phosphorus. Fertlisers provide combinations of these important nutrients. There are a few other nutrients that can also help and include sulphur, calcium and magnesium.
You will hear some gardeners also talk about having molybdenum, iron, zinc, copper, boron and manganese in their soil. Don't worry too much about those as they are known as trace elements and most fertilsers have these included in the right amounts, and also most soil will already contain some of these.
The single most important nutrient is nitrogen as it is that which will make for strong leafy growth
3 Different Types Available on the UK Market
When you look at the shelves in any garden centre, you will see hundreds of different types of fertlisers for sale. For a beginner this can be especially confusing. Hopefully we can make understanding these a great deal easier. These can be broken into the general classifications:
- General Fertlisers
- Specific Fertilisers
- Straight Fertlisers
General Fertilisers
These are the most popular as they are very good for general purpose use around the garden and lawns. These contain the important three elements of nitrogen(N), phosphate(P) and potash(K). If you pick one up you will typically see something like NPK 5:5:5 which simply means these nutrients have an equal balance do great for general purpose use.
These are sold in either liquid form or as a powder which can be quickly and easily mixed. You may be familiar with the Growmore formula of NPK 7:7:7. Just be aware that Growmore is actually a formula and not a brand name. Different brands such as Miracle-Gro, Westland, Doff etc will also have Growmore included as a formula.
These can be used 1-2 times a week to the whole garden. The one shown above is a typical sized 10 kg tub.
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The organic version of general fertlisers will contain blood, bone and fish. They don't follow any specific formula so you need to read the instructions carefully.
One final thing to point out about the inorganic general fertilisers is that some may contain a slightly different formula and a typical popular variant is NPK 5:6:10 which means it has a higher concentrate of potash. This is aimed at tomato plants who grow better with a higher dose of potash. The one shown above contains 1 litre.
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Specific Fertilisers
These are also referred to as proprietary fertlisers, or controlled release plant food. These are aimed at specific plants such as lawns, roses, flowers and house plants. They will be the most expensive of the fertilisers.
These are also good to use in containers, hanging baskets as they come in liquid forms or controlled release granules.
Many gardeners also use these to help grow flowers, cucumbers and peppers.
Tomato fertilisers are also very popular and contain a high potash (K) content. As well as potash they will also include iron and magnesium.
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Straight Fertilisers
This gets a lot more complicated as there are many straight fertilisers. As you can see from the two types above, they are aimed at general purpose and also at specific types of growing and plants.
Straight fertlisers will contain larger proportions of one nutrients only. This allows a gardener to add a particular element depending on what they are growing. They will usually apply this as a top dressing. We have listed those below with an explanation of each.
Nitrogen
The use of a nitrogen based fertiliser will promote the healthy green growth of both leaves and stems. Typically, if you notice pale green foilage or any type of stunted growth, that points to not enough nitrogen.
You also need to be careful, as at the other side of the scale, too much nitrogen can prevent fruiting or ripening. It will also cause a soft sappy type of growth, and that is highly susceptible to diseases and pests.
That is why this is usually better purchased as a slow release format shown to the left.
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Nitrochalk
Nitrochalk is an inorganic fertiliser that contains around 26% nitrogen. It should really only be used on acidic soil types and is usually applied as a top dressing.
This type of fertiliser is mainly used by those who like to grow vegetables such as salad crops or leafy brassicas.
With this type of fertiliser, the nitrogen is released very quickly to help promote the leafy type of growth quickly.
Just be aware that this type of fertiliser does not keep for very long so only buy the amount that you are going to use straight away.
Sulphate of Ammonia
This is one of the most popular fertilisers and used mainly by vegetable gardeners. It is a cheap inorganic fertiliser that contains about 21% nitrogen.
Like the Nitrochalk fertiliser the nitrogen is released very quickly to help promote strong healthy growth. This particular type is normally put on as a top dressing on alkaline or neutral types of soil.
It does stop leaves from turning yellow, and as it is applied in a granular form it is easy to get into the ground. Don't over apply this though as too many applications may turn your soil to an acid type.
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Nitrate of Soda
This is another popular fertiliser. It is used as a fast acting inorganic fertiliser and for general purpose use.
This one contains about 16% nitrogen and is mainly used as a top dressing.
It is very popular with beetroot growers, and vegetables such as celery also react well to a nitrate of soda based fertiliser.
Dried Blood Fertiliser
Yes we know it sounds horrible, but it works very quickly on actively growing plants. It does need to be used sparingly though.
Dried blood is considered by many gardeners to be a tonic for many plants and that is why it is such a popular choice.
These normally contain around 13% nitrogen and are used on many types of vegetables including the potato and brassicas.
It is also very good for plants that are growing in a greenhouse or conservatory.
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Hoof and Horn Fertiliser
Hoof and horn fertilisers are slow to fast acting fertilisers and the rate depends on the size of the particles.
Like the dried blood they contain around 13% nitrogen and this one is also used as a top dressing.
This is an organic fertiliser and as you can see, these tend to be more expensive than inorganic ones. It is normally applied as a top dressing at a rate of 35 grams per square metre.
Phosphate
Phosphate, also known as phosphorus is made to help the growth of healthy roots. Many gardeners also use it to help mature and ripen fruits and seeds.
Most gardeners will not actually have a phosphate deficiency, but it can be common in heavy clay type soil and in areas subject to very heavy rainfall.
You can see the symptoms as a dull green or purple foilage and is usually accompanied by stunted growth.
All phosphate fertilisers are slow acting and need to be applied as close to the roots as possible.
Super Phosphate
This is an inorganic fertiliser that contains about 17% phosphate. It is a very slow release fertiliser and should be applied in the winter or early spring to get the best results from this type of fertiliser.
This type of early application will slowly release down into the soil and roots in time for the beginning of the growing season.
Over time though this may make soil quite acidic so again this should not be over used.
Bonemeal Fertilisers
This is an inorganic fertiliser of phosphate that is made by crushing and grinding bones. It is then sterilised and when applied releases its nutrients slowly into the ground.
Very fine grades of this will act much quicker than rougher grains. This is a very popular choice of fertiliser s it lasts for 3-4 years.
It is used a lot by gardeners who grow shrubs or herbaceous perennials and is also used as a base dressing for vegetables.
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Potash Fertilisers
Potash, sometimes referred to as potassium, is an excellent fertiliser for flower production and for any fruiting crops.
Plants on light or chalky soils will typically suffer from a lack of potassium. The signs are discoloured leaves or patchy leaves.
The symptoms are reduced growth, this shoots and soft growth which is vulnerable to diseases and to pests.
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Sulphate of Potash
This is an inorganic fertiliser that contains about 50% of potassium. It does need to be applied in early Spring.
This is a fast acting and soluble but it is known to leak out of the soil
This is not that popular of a fertiliser and is ideal for fruit trees, flowers and bushes.
It is applied by scattering evenly around plants and lightly forked or hoed in.
Most fertilisers should be sown at a rate of 35 grams per square metre or 1 ounce per square yard. On any good fertiliser, there will be sowing rates shown, and it is always best to follow their instructions.
Most manufacturers will also recommend wearing gloves when applying any type of fertiliser.
