Fertilizer for Plants in the UAE: NPK Numbers and How to Choose

The three numbers on a fertilizer bag, such as 20-5-8 or 14-10-27, are the percentages by weight of nitrogen (N), phosphate (P₂O₅) and potash (K₂O). Pick a nitrogen led feed for lawns and leafy growth, a potash led feed for flowering and fruiting plants, and a product with magnesium and trace elements for palms, then let the label rate, not the bag size, decide how much you use. In sandy UAE soil and hot pots, how often and how much you feed matters as much as which numbers you buy.

By the end of this article you will be able to read any fertilizer label, work out how many grams of nitrogen a dose really supplies, compare two products on nutrient content rather than pack weight, mix the right amount for a 1 L, 5 L or 16 L sprayer, and spot when a plant needs something other than more fertilizer.

What the three numbers on a fertilizer mean

The numbers are percentages by weight, always in the same order:

• N, nitrogen. Drives leaf and shoot growth and green colour. As nitrate it dissolves freely, so it moves with irrigation water through sand.
• P, phosphate (written on labels as P₂O₅). Needed for roots, energy transfer inside the plant, flowering and seed.
• K, potash (written as K₂O). Involved in water control in the leaves, and linked to fruit fill and quality.

Clemson University Extension explains how to read the guaranteed analysis. A fertilizer containing all three primary nutrients is called complete; equal numbers, such as 10-10-10, are called balanced; and a product that leaves one out, such as 24-0-11, is incomplete and suits soil that already has enough of the missing nutrient. Clemson describes the rest of the bag as inert material or nutrient carrier that helps you spread the nutrients evenly, although many products also include magnesium, sulphur, trace elements or organic matter in that remainder.

Why phosphate and potash are written as oxides

Labels report phosphorus as P₂O₅ and potassium as K₂O by long convention. Penn State Extension points out that these oxides do not actually exist in the bag and gives the conversions: % P₂O₅ x 0.44 = % P, and % K₂O x 0.83 = % K. So a 20% phosphate figure means about 9% phosphorus, and 10% potash means about 8% potassium. You rarely need this, because recommendations are also written in oxide terms, but it explains why the middle and last numbers overstate the element.

A worked example: what is really in the bag

Take COMPO EXPERT Floranid Twin Turf 20-5-8, a lawn fertilizer. Every 1 kg contains:

• 200 g of nitrogen (20%)
• 50 g of phosphate (5%), which is about 22 g of elemental phosphorus
• 80 g of potash (8%), which is about 66 g of elemental potassium
• plus 2% magnesium oxide

The product page rate is 25 to 40 g per m2. At 25 g that is 5 g of nitrogen per square metre; at 40 g it is 8 g. That one calculation lets you compare any lawn feed with Floranid: divide the nitrogen you want by the first number as a decimal.

How to choose: match the numbers to the job

Start with the plant and the symptom, then the numbers. The ratio between the three figures tells you what a product is built for.

Lawns

Lawns need nitrogen above all, but the amount and timing depend on the grass and how fast it is growing. Floranid’s page says its nitrogen comes from Isodur and Crotodur, slow release forms, and gives a rate of 25 to 40 g per m2 every 8 to 10 weeks during the active growing season, watered in straight away. For mowing heights, watering and a month by month plan, see our guide to maintaining a healthy lawn in the UAE.

Worked doses for Floranid, from the page rate:

• 1 m2 test patch: 25 to 40 g, weighed on a kitchen scale.
• 20 m2 front lawn: 0.5 to 0.8 kg.
• 100 m2 villa lawn: 2.5 to 4 kg, supplying 0.5 to 0.8 kg of nitrogen.
• A 25 kg bag covers about 1,000 m2 at 25 g per m2, or about 625 m2 at 40 g per m2.

Our pick for UAE lawns

COMPO EXPERT Floranid Twin Turf 20-5-8 (+2 MgO), 25 kg

A nitrogen led, slow release granule for a Bermuda or overseeded lawn that needs steady feeding rather than one quick flush.

• Product page analysis: 20% N, 5% P₂O₅, 8% K₂O and 2% MgO, with Isodur and Crotodur nitrogen
• Page rate: 25 to 40 g per m2 depending on turf condition, watered in straight away
• Page interval: every 8 to 10 weeks in the active growing season

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Read the label for your turf before use, and keep children and pets off the lawn until the granules are watered in.

Vegetables, herbs and flowers

Fruiting crops need nitrogen to build the plant first, then steady potash as fruit sets. A potash led soluble feed such as Phostrogen 14-10-27 or AGS 3-5-11 suits that second stage. Leafy crops such as lettuce, rocket and herbs grown for leaves do better with a nitrogen led feed. If you are growing tomatoes or peppers, our potash fertilizer guide explains when to add potassium on its own.

Worked doses for Phostrogen, from the page rate of 1 level spoon (5 g) per 4.5 litres:

At full strength that solution carries about 0.16 g of nitrogen and 0.30 g of potash in every litre. The page gives an interval of every 7 to 14 days in the growing season.

Our pick for fruiting vegetables and flowers

Phostrogen All Purpose Plant Food

A potash led soluble feed for tomatoes, peppers, flowering plants and mixed pots once they are established.

• Product page analysis: NPK 14-10-27 with 2% MgO and trace elements (Fe, Mn, Cu, Zn, B, Mo)
• Page rate: 1 level spoon (5 g) per 4.5 litres, half strength for seedlings
• Page interval: every 7 to 14 days in the growing season; 400 g and 800 g sizes

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Wear gloves when handling, avoid eyes and mouth, and store it sealed, cool and dry, out of reach of children and pets.

Indoor plants and balcony pots

Indoor plants grow slowly, so a modest nitrogen led feed given monthly is usually enough. The AGS 9-2-5 page gives 1 level spoon (the spoon is inside the pack) in 3 litres of water for indoor plants and 3 level spoons in 10 litres for garden plants, repeated monthly or as needed, and says to avoid applying it directly on the foliage. The page does not say how many grams the spoon holds, so we cannot convert this to grams.

• 1 L: a third of a spoon is hard to measure, so mix 3 L with 1 spoon and keep the rest for the next pots.
• 5 L can: 1.5 level spoons (garden rate).
• 16 L tank: about 5 level spoons (4.8 at the garden rate).

Our pick for indoor and leafy plants

AGS All Purpose Plant Food 9-2-5, 250 g

A nitrogen led soluble feed in a small pack, sized for houseplants and balcony pots fed once a month.

• Product page analysis: NPK 9-2-5, water soluble, 250 g
• Page rate: 1 level spoon in 3 L for indoor plants, 3 level spoons in 10 L for garden plants
• Page interval: monthly or as required; apply around the root zone, not on the leaves

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The page does not state the spoon weight. Keep out of reach of children, store cool and dry, and do not exceed the label dose.

Palms and fruit trees

Palms need attention to potassium, magnesium and manganese as well as nitrogen. University of Florida IFAS Extension calls potassium deficiency the most common nutritional disorder of palms and, for Florida landscapes, recommends a fertilizer labelled 8-2-12+4Mg or 8-0-12+4Mg with slow release macronutrients, spread evenly under the whole canopy three times a year from spring to autumn, with no winter feed. It also warns that high nitrogen lawn fertilizer applied even 30 feet (about 9 m) from a palm can trigger potassium deficiency, and says not to cut off yellowing fronds, which can signal a deficiency.

Those figures are for Florida, not the UAE, but the logic travels: potash at least equal to nitrogen, plus magnesium. Palm Secrets, sold as an organic mineral fertilizer, is listed as 12-6-24 with 2% MgO, 0.5% trace elements, 6% humic acid and 8% organic matter, a 1 to 2 nitrogen to potash ratio. Its page gives no application rate, so follow the bag label. For more, see our citrus fertilizer guide for fruit trees in pots and gardens.

The science: why the same numbers behave differently

Old leaves or new leaves: where the symptom shows

The UC Statewide IPM Program describes nitrogen shortage as older leaves turning uniformly pale green to yellowish while new growth stays green but sparse. Potassium shortage shows first on older leaves as yellow or brown tips, margins and patches between the veins. Iron and manganese shortage show on new leaves, which are small and yellow with green veins. Where the symptom appears is the clue: shortages that show on old leaves and shortages that show on new leaves have different causes, so yellow new leaves are not fixed by more NPK.

Alkaline sandy soil locks up micronutrients

UC IPM notes that iron and manganese deficiencies are common in high pH (alkaline) and sandy soils, and that a pH of about 6 to 7.5 suits most plants. Many UAE gardens have sandy soil, and where it is also alkaline, yellow young leaves are more often an iron problem than a nitrogen one. Our iron chlorosis guide covers that case, and our Epsom salt guide covers magnesium.

Fertilizers are salts

Every fertilizer dissolves into salts. The University of California Master Gardener houseplant page explains that fertilizer dissolved in water becomes a soluble salt, that salts concentrate as water evaporates, and that the signs are a yellow or white crust on the soil, a salt ring at the pot rim, brown leaf tips, lower leaves dropping and wilting. In a UAE summer, pots dry out daily and salts build quickly, which is why overdosing a pot does more harm here than in a cool climate.

Sand holds very little

Sandy soil has little clay or organic matter to hold dissolved nutrients and water. An International Center for Biosaline Agriculture (ICBA) project brief from Dubai (2016) measured sandy soil holding about 5% water at a suction of 0.1 bar, against about 61% for compost. Dissolved nitrogen in a sandy bed can wash below the roots with the next heavy irrigation, so smaller, more frequent feeds or a slow release product waste less than one large dose.

How much and how often: calculate it yourself

Iowa State University Extension sets out a simple method: divide the nitrogen rate you want by the nitrogen fraction of the fertilizer, then multiply by the area. Here is the same method in metric:

1. Find the nitrogen you want per square metre, from a soil test report or the crop recommendation. As an example only, say 5 g of N per m2.
2. Divide by the first number as a decimal. For a 12-12-17 product: 5 divided by 0.12 is about 42 g per m2.
3. Multiply by the bed area. A 1 m by 4 m bed is 4 m2, so about 167 g.
4. Check the result against the product label. If the label rate is lower, use the label rate.

The same arithmetic compares packs. A 250 g pack of 9-2-5 holds 22.5 g of nitrogen; an 800 g pack of 14-10-27 holds 112 g. So the 800 g pack holds about five times the nitrogen of the 250 g pack, not about three times as its weight suggests. Compare grams of nutrient, not grams of product.

Granules, powder or liquid?

Clemson also recommends a product with 50% or more of its nitrogen in slow release form when you want a long, steady supply. Liquid feeds are covered in detail in our liquid fertilizer guide.

What is not an NPK fertilizer

Some products on the fertilizer shelf have a different job. HUMFERT 15% humic acid is described as a soil enhancer, vermicompost improves sandy soil structure, and seaweed extracts are biostimulants. Some contain small amounts of nutrients, so check the guaranteed analysis, but do not count them as a full feed.

The opposite case is a single purpose product with a zero in it. YAMFERT MKP 0-52-34 is monopotassium phosphate: no nitrogen, a lot of phosphate and potash. Its page gives a foliar rate of 2 to 5 g per litre of water, applied during flowering and fruit development, and says to dissolve it completely first.

• 1 L sprayer: 2 to 5 g.
• 5 L sprayer: 10 to 25 g.
• 16 L knapsack: 32 to 80 g.
• Each gram supplies 0.52 g of phosphate and 0.34 g of potash.

Start at the low end of that range on a few plants and check for leaf scorch over the next few days before spraying the whole crop. Use it when a real shortfall is suspected, not as a routine feed, because adding phosphate to soil that already has enough does nothing useful.

For a phosphate and potash shortfall

YAMFERT MKP 0-52-34, 1 kg

A nitrogen free source of phosphate and potash for flowering and fruiting crops when those two are what is short.

• Product page analysis: 0% N, 52% P₂O₅, 34% K₂O
• Page foliar rate: 2 to 5 g per litre of water, fully dissolved
• Page timing: during flowering and fruit development

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Not a complete feed. Store the bag sealed, dry and out of sunlight, away from children and pets.

Products compared

A UAE feeding timeline

Palm timing in this table is adapted from Florida guidance; lawn and vegetable timing follows active growth, so feed when plants are growing and follow each label interval.

Villa, balcony or farm

• Villa garden: keep lawn feed off palm root zones, because high nitrogen near palms can bring on potassium deficiency.
• Balcony pots: soluble feeds at the label rate, and flush pots with plain water to stop salts building up.
• Farm or large plot: base rates on a soil and water test, and calculate product from the nitrogen recommendation as shown above rather than from spoon measures.

Signs you are overdoing it

• Brown, crisp leaf tips and edges, especially after a feed.
• A white or yellow crust on the soil surface or around the rim of pots.
• Lots of soft green growth but few flowers or fruit, a common sign of too much nitrogen on fruiting plants.
• Lower leaves dropping and plants wilting even though the soil is moist.

Heat, salty irrigation water and poor drainage cause the same signs, so pause feeding and check the cause. For a pot, the UC Master Gardener page advises scraping off any crust (no more than about 6 mm of soil), then running through plain water equal to twice the volume of the pot and letting it drain completely, at least every 4 to 6 months. A 10 L pot therefore needs about 20 L of water. Never leave the pot standing in the drained water, because the salts can be taken back up.

Common mistakes

• Buying on the biggest numbers. A 20-20-20 is not better than a 10-10-10; it is twice as concentrated, so you use half as much. Compare grams of nutrient, not the label size.
• Feeding yellow new leaves with NPK. New leaves yellow with green veins usually point to iron or manganese, which NPK does not fix.
• Adding phosphate every time. Clemson advises against applying all three nutrients when phosphorus and potassium are already adequate. Adding phosphate to soil that already has enough does nothing useful.
• Using lawn feed on vegetables. Some lawn products contain weed killers. Use only a product whose label lists your crop.
• Feeding a dry or wilting plant. Water first, feed the next day. Salts in dry soil scorch roots.
• Topping up just to be sure. In sand and hot pots, extra fertilizer becomes extra salt.

Troubleshooting: you fed it and it did not help

• Still pale all over after two feeds: check drainage and roots. UC IPM lists waterlogging, salinity, nematodes and root rot among the causes that mimic deficiency by damaging roots.
• Got worse after feeding: stop, flush the pot or water the bed deeply, and resume at half strength after new growth appears.
• Yellow new leaves: iron or manganese; see the iron chlorosis guide.
• Older palm fronds with yellow, orange or brown flecks, or browning along the margins and tips: likely potassium; check the feed’s potash and keep lawn nitrogen away.
• No clear pattern: get a soil and water test from an accredited laboratory before buying more fertilizer. A test turns guesswork into a recommendation you can calculate from.

Safety and storage

• Wear gloves when handling powders and granules, and avoid contact with eyes and mouth, as the Phostrogen page advises.
• Keep children and pets off a lawn until granules are watered in, as the Floranid page says.
• Store fertilizers sealed, cool and dry, out of reach of children and pets and away from food, as the MKP and Phostrogen pages advise.
• Sweep granules off paving and driveways back onto the lawn so they do not wash into drains.
• Never mix fertilizers into the same tank as a pesticide unless both labels allow it.

Frequently asked questions

What does 20-20-20 fertilizer mean?

It declares 20% nitrogen, 20% phosphate (P₂O₅) and 20% potash (K₂O) by weight. Using Penn State’s factors, that is about 9% elemental phosphorus and 17% potassium. Whether it suits you depends on the plant and what the soil already holds.

Which NPK is best for flowering?

A potash led feed with moderate nitrogen, such as 14-10-27, once plants are established. Too much nitrogen tends to give leaf at the cost of flowers, so choose a feed that is not nitrogen led.

Which fertilizer is best for vegetables in the UAE?

Leafy crops prefer a nitrogen led feed; tomatoes, peppers, cucumbers and melons prefer a potash led one once fruit sets. In sand, feed little and often at the label rate.

Is organic fertilizer better than chemical fertilizer?

Neither is automatically better. An organic based soluble feed can work quickly; compost and manure feed slowly and also improve sandy soil. Choose by the analysis, the label directions and what the plant needs.

How often should I fertilize potted plants?

Follow the label: Phostrogen gives every 7 to 14 days in the growing season, AGS monthly. Feed less when growth slows and flush pots with plain water every few months.

Can I use lawn fertilizer on vegetables?

Only if its label lists the edible crop. Some lawn products include herbicides, and a lawn feed’s high nitrogen is not what fruiting crops need.

Which fertilizer is best for palm trees in the UAE?

One with potash at least equal to nitrogen, plus magnesium and trace elements. UF/IFAS recommends 8-2-12+4Mg for Florida palms; Palm Secrets 12-6-24 with 2% MgO and trace elements is a palm fertilizer in our range. Follow its bag label, as the page gives no rate.

Why are my leaves turning yellow after fertilizing?

Brown edges and yellowing after a feed usually mean salt damage from too strong a dose or a dry root zone. Water deeply, flush pots and resume at half strength.

Still unsure which numbers you need? Browse our full fertilizer range or message us with what you are growing and where, and we will help you work out the product and the dose.