Tomato Nutrient Deficiency: Signs, Causes and the Fertilizer That Fixes It
Tomato nutrient deficiency is one of the first things to check when the leaves of your kamatis (tomato) turn yellow, purple or burnt at the edges. On Philippine farms the usual ones are nitrogen, potassium, calcium, phosphorus, magnesium, boron, zinc, sulfur, iron and manganese. This guide shows where each one starts, how to be sure, and the fertilizer that fixes it.
Start with one question: did the change begin on the old leaves or on the young ones? Nitrogen, potassium, phosphorus and magnesium move inside the plant, so a shortage shows on the old, lower leaves first. But calcium, boron, zinc, sulfur, iron and manganese stay where the plant first put them, so the young leaves and the growing tip show it first. After that, the color and the pattern narrow down which tomato nutrient deficiency you have, and a soil test confirms it. Each one below has its signs, its causes and its fix.
Tomato nutrient deficiency signs, old leaves and young leaves
Shows first on the old leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Nitrogen | old, lower leaves, the whole plant | Lower leaves turn pale yellow first and the plant looks thin and spindly. | Urea 46 0 0, Ammonium sulfate 21 0 0 |
| Potassium | old, lower leaves, leaf edges and tips | Old leaves get scorched, curled edges and the fruit ripens in green or yellow blotches. | Muriate of potash 0 0 60, Sulfate of potash 0 0 50 |
| Phosphorus | old, lower leaves, the whole plant | Small, stiff, dark bluish green plants with purple undersides on the lower leaves. | Ammonium phosphate 16 20 0, Diammonium phosphate 18 46 0 |
| Magnesium | old, lower leaves, between the veins | Lower leaves turn yellow between green veins, starting from the leaf edge, while fruits are filling. | Magnesium sulfate (Epsom salt), Dolomite |
Shows first on the young leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Calcium | fruit, grain or tubers, young leaves and the tip | A dark, sunken, leathery patch at the bottom end of the fruit, opposite the stem. | Calcium nitrate, Calcium chloride |
| Boron | young leaves and the tip, fruit, grain or tubers | Brittle leaf stalks that snap, a dying tip, and fruits with rough, cracked or corky skin. | Borax, Solubor (sodium borate) |
| Zinc | young leaves and the tip, between the veins | Short, bunched shoots with small, stiff, leathery leaves that curl down. | Zinc sulfate, Agricultural lime |
| Sulfur | young leaves and the tip, the whole plant | Young top leaves turn pale yellow green, stiff and curled down, with purple stems. | Ammonium sulfate 21 0 0, Gypsum |
| Iron | young leaves and the tip, between the veins | New top leaves turn yellow with a fine net of green veins, but keep their normal shape. | Ferrous sulfate, Iron chelate |
| Manganese | young leaves and the tip, between the veins | Young leaves get orange yellow mottling between green veins with tiny dark brown dots. | Manganese sulfate |
Before you buy fertilizer for a tomato nutrient deficiency
So use the table to pick the likeliest tomato nutrient deficiency, then read its section below. Also keep in mind that dry soil, standing water, cold nights, a pest or a disease can look the same. That is why it pays to check the roots and the whole field first.
Nitrogen deficiency in tomato
The oldest, lowest leaves turn pale green and then yellow, and the yellowing climbs up the plant as the shortage gets worse. Leaflets stay small and stand upright, and the veins on the underside can look pink or purple. Shoots are thin, flower buds may yellow and drop, and the fruits that set stay small. In bad cases the old leaves turn fully yellow or brown and fall off. You see it most at this stage: any time, but most often from early growth to fruit set when the plant is growing fast.
Why nitrogen deficiency happens in kamatis
Sandy or light soils, heavy rain or heavy watering that washes nitrogen down, low organic matter. Fresh straw or raw manure that ties up nitrogen while it rots. Very low or very high soil pH also makes it worse.
How to tell it apart
Sulfur shortage also makes the plant pale. But it starts on the young top leaves, while nitrogen starts on the old bottom leaves. To be sure, look at where the yellowing starts (bottom leaves first). A soil test for organic matter and a leaf tissue test give a firm answer. A quick check is to spray a few plants with urea and see if new leaves green up within a week.
What to apply for nitrogen deficiency
Side dress with urea or ammonium sulfate based on your soil test, split into small doses. For a fast green up, spray urea at 10 grams per liter of water (160 grams in a 16 liter sprayer). Repeat every 15 days, or give two sprays one week apart. Water after side dressing so the fertilizer reaches the roots. Side dress 5 to 10 grams of Urea 46 0 0 a plant, about 1 to 2 bags per hectare, every two to three weeks from flowering, and water it in.
- Urea 46 0 0
- Ammonium sulfate 21 0 0
- Complete 14 14 14
- Calcium nitrate
Sold here with nitrogen: Atlas Granular Urea (46 0 0) by Atlas Fertilizer, Crown Champion Ammonium Sulfate by Aqua Hydroponic Prime Ventures (21 0 0 with 24 percent sulfur), Agripower 46 0 0 (Locally Blended) Coated by Green Acres Agri Tech and Amigo Planters Sabic Zinc Coated Urea by La Filipina (46 0 0 with 0.1 percent zinc). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to urea fertilizer, and the page on nitrogen deficiency in every crop. In anee.io, Anee, the smart farm technician, reads a photo of the leaf and tells you which nutrient is short.
To keep it away, mix compost or well rotted manure into the beds and split nitrogen into several side dressings instead of one big dose. Do not bury fresh straw or raw manure just before planting.
Potassium deficiency in tomato
The edges of the older leaves turn yellow, then brown and dry, and the scorch moves in between the veins. Small whitish dead spots can appear inside the yellow areas, and the leaf edges curl. On the fruit, patches near the stem stay green or yellow when the rest turns red. The flesh under them is firm and tasteless. Fruit can also be soft, hollow or poorly colored. You see it most at this stage: most often from fruit set to harvest, when the fruits pull a lot of potassium out of the leaves.
Why potassium deficiency happens in kamatis
Sandy soils, acid soils, heavy rain or irrigation that leaches potassium, soils with low potassium reserves, and soils rich in magnesium. Drought and cool cloudy weather make blotchy ripening worse.
How to tell it apart
Salt damage also burns leaf edges. A salty soil or irrigation water test tells them apart. To be sure, A soil test for exchangeable potassium and a leaf tissue test. Check the potassium with a leaf test, or press leaf sap onto a handheld potassium meter.
What to apply for potassium deficiency
Apply muriate of potash or sulfate of potash based on your soil test, split into two or three side dressings. For a quick fix, spray sulfate of potash at 10 grams per liter of water (160 grams in a 16 liter sprayer) with a sticker in the morning. Give three sprays one week apart. On acid soil, lime or dolomite helps the plant hold and use potassium. A usual dose is 1 to 2 bags of Muriate of potash 0 0 60 or Sulfate of potash 0 0 50 per hectare, split from flowering to fruit fill.
- Muriate of potash 0 0 60
- Sulfate of potash 0 0 50
- Potassium nitrate 13 0 46
- Complete 14 14 14
Sold here with potassium: Atlas Muriate of Potash (MOP) by Atlas Fertilizer (0 0 60), Simplot Sulfate 0 0 50 by Nutranta, Potassium Nitrate by Parafield (13 0 46) and Qrop Mix Production 14 0 23 plus 13 Cao by Farmtech Agriland (14 0 23 with 9.3 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to potash fertilizer, and the page on potassium deficiency in every crop.
To keep it away, give potassium before flowering and again during fruiting, add organic matter, and keep soil pH above 6.
Calcium deficiency in tomato
A small light brown or water soaked spot appears at the blossom end of young green fruit. It grows into a sunken, dark brown to black, leathery patch with a sharp border, and the fruit often ripens early. Some fruits have hard brown tissue inside with no outside mark. In severe cases the top leaves curl, their edges die and the growing tip dies. You see it most at this stage: early fruit growth, usually on the first fruit clusters and in hot, dry spells.
Why calcium deficiency happens in kamatis
Usually not a lack of calcium in the soil but uneven watering: when the soil dries out or stays waterlogged, too little calcium moves with water into the fruit. Sandy and acid soils, salty soil, too much nitrogen or potassium, root damage and large fruited or elongated varieties raise the risk.
How to tell it apart
Sunscald makes a pale or white patch on the side facing the sun, not at the bottom end. Fruit rots from disease are soft and often show mould from the start. To be sure, check the pattern first: bottom end of the fruit, early fruits, after a dry spell. A soil test for calcium and pH tells you if lime or gypsum is needed. Keep a watering record to see if the soil has been drying out between waterings.
What to apply for calcium deficiency
Water deeply and regularly so the root zone never dries out or stays soggy, and mulch to hold moisture. Try a calcium chloride spray at 5 grams per liter of water (80 grams in a 16 liter sprayer), three times two weeks apart. On acid soil, lime by the soil test: usually 1 to 3 tons of Agricultural lime or Dolomite per hectare, mixed in 2 to 4 weeks before planting. Use gypsum on soil that is not acid. Remove damaged fruits. They will not recover.
- Calcium nitrate
- Calcium chloride
- Agricultural lime
- Dolomite
- Gypsum
Sold here with calcium: Micronized Activated Calcite by CMCS Agricultural Products (37.6 percent calcium), Dolomite by A6 Agrisource (24 percent calcium and 11 percent magnesium), Titon Pro by Vast Agro (27.2 percent calcium, 6.1 percent silicon and 3.6 percent magnesium) and Crown Champion Nitrogen Calcium Compound (Cal Nit) by Aqua Hydroponic Prime Ventures (15 0 0 with 18 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to fertilizer for tomatoes, and the page on calcium deficiency in every crop.
To keep it away, lime acid soil before planting, mulch, water on a steady schedule, and avoid heavy nitrogen or ammonium fertilizer. Calcium nitrate as part of the side dressing supplies both nitrogen and calcium. Keep potash in balance with magnesium and calcium.
Phosphorus deficiency in tomato
Plants stay small with thin stems and few side branches, and the leaves turn dark blue green. The undersides of the older leaves and their veins turn purple or reddish, starting at the edges, and leaflets curl down. Later the old leaves get brown dead patches, yellow and drop early. Roots are small and brownish, and flowering and fruit set are delayed. You see it most at this stage: seedling and early growth after transplanting, especially in cool weather.
Why phosphorus deficiency happens in kamatis
Strongly acid soils and iron rich soils that lock up phosphorus, very alkaline soils, low organic matter, cold or waterlogged soil, and weak or damaged roots.
How to tell it apart
Cold nights alone can turn seedlings purple for a while even when soil phosphorus is fine. The color fades once it warms up. To be sure, A soil test for available phosphorus and pH, plus a leaf tissue test if the soil looks fine.
What to apply for phosphorus deficiency
Apply phosphorus at planting based on your soil test, placed in the hole or band near the roots, not broadcast on top. For a quick boost, try spraying DAP at 10 grams per liter of water (160 grams in a 16 liter sprayer), twice two weeks apart. Correct very acid soil with lime so phosphorus stays available. A usual basal dose is 4 to 6 bags of Complete 14 14 14 per hectare, 10 to 20 grams a hill, mixed into the soil at transplanting.
- Ammonium phosphate 16 20 0
- Diammonium phosphate 18 46 0
- Complete 14 14 14
- Agricultural lime
Sold here with phosphorus: Philphos 18 46 0 (Di Ammonium Phosphate), Atlas Super Gro (16 20 0) by Atlas Fertilizer, Amigo Planters Granular Single Super Phosphate by La Filipina (0 18 0 with 11 percent sulfur) and Triple Super Phosphate by Newman Chemicals (0 46 0). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to 16 20 0 fertilizer, and the page on phosphorus deficiency in every crop.
To keep it away, use a starter of 16 20 0 or 14 14 14 at transplanting, keep the soil near pH 6 to 7, and add compost or manure.
Magnesium deficiency in tomato
Older leaves turn yellow or yellow orange between the veins while the main veins stay green. The yellowing starts at the leaf edges and moves inward. Small whitish to light brown dead spots form in the yellow areas. The problem moves from the bottom of the plant upward, and in bad cases whole lower leaves die and yield drops. You see it most at this stage: fruit set and fruit filling, when the plant moves magnesium from old leaves to the fruits.
Why magnesium deficiency happens in kamatis
Sandy and acid soils, heavy rain, and heavy use of potash or ammonium fertilizer, which push magnesium out of the root zone and block its uptake.
How to tell it apart
Iron and manganese shortage also yellow between the veins but on the young top leaves. Nitrogen shortage yellows the whole leaf, veins too. To be sure, leaf tissue test and a soil test for magnesium and potassium. A high potassium to magnesium balance points to magnesium shortage.
What to apply for magnesium deficiency
Spray magnesium sulfate (Epsom salt) at 20 grams per liter of water (320 grams in a 16 liter sprayer), twice two weeks apart. For the soil, try magnesium sulfate in a band near the plants at about 80 kg per hectare. Try dolomite at about 2 tonnes per hectare on acid soil. Do not apply potash and magnesium fertilizer at the same time.
- Magnesium sulfate (Epsom salt)
- Dolomite
- Kieserite
Sold here with magnesium: Dolomite by A6 Agrisource (24 percent calcium and 11 percent magnesium), Agsmart Kieserite Granule (20 percent sulfur and 16.3 percent magnesium), DDDD Planter's Choice Magnesium Sulphate Monohydrate by Modern Time (15.1 percent magnesium) and Zetryl MAG 9 by Zetryl Chem (9 percent magnesium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to complete fertilizer, and the page on magnesium deficiency in every crop.
To keep it away, use dolomite instead of plain lime on acid soil and keep potash rates in line with the soil test.
Boron deficiency in tomato
Young leaves stay small, curl inward and become misshapen, with yellow to orange spots between the veins. Leaf stalks become brittle and snap easily. The growing tips of the main shoot and side shoots can die, and stems become thick, stiff and short. Fruits ripen unevenly and show rough, cracked skin or corky pits, and some fruits are hollow. You see it most at this stage: flowering and fruit set, and after dry spells.
Why boron deficiency happens in kamatis
Sandy soils where boron washes out, soils low in organic matter, overliming or alkaline soil, heavy nitrogen or calcium, and drought.
How to tell it apart
Calcium shortage also kills the growing tip but brings blossom end rot and dead leaf edges. Fruit cracking also comes from sudden heavy watering after a dry spell. To be sure, soil test for available boron and a leaf tissue test. Boron has a narrow safe range, so confirm before applying more than one dose. In a soil test, less than 0.5 ppm of boron is low.
What to apply for boron deficiency
Spray borax at 1 gram per liter of water (16 grams in a 16 liter sprayer), or up to 3 grams per liter (48 grams in a 16 liter sprayer) twice two weeks apart. For the soil, give borax at about 10 kg per hectare. Do not mix borax with calcium or ammonium fertilizers in one application, and never double the dose. Too much boron burns leaf edges.
- Borax
- Solubor (sodium borate)
- Boric acid
Sold here with boron: Etifert 11 (Borax Decahydrate) by Zetryl Chem (11 percent boron), Fertibagra 15G by Unilox Far East Resources (14.6 percent boron), B17 (Boric Acid) by Newman Chemicals (17 percent boron) and Better Yield by Bacphil Planters Fertilizer (0 0 0.9 with 10 percent boron). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to foliar fertilizer, and the page on boron deficiency in every crop.
To keep it away, include boron in the basal fertilizer on sandy or heavily limed fields and keep organic matter up. Test the soil every two or three years.
Zinc deficiency in tomato
Leaves are small, thick and leathery, and the leaflet edges curl down. Yellowing shows between the veins and along the midrib, which can turn white in bad cases. The spaces between leaves on the stem become short, so the plant looks bunched and stiff. Growth and fruiting both drop. You see it most at this stage: early vegetative growth, especially after a cold or waterlogged spell.
Why zinc deficiency happens in kamatis
High pH or overlimed soil, soils very high in phosphorus or heavily fertilized with phosphorus, waterlogged soil, and organic or peaty soils.
How to tell it apart
Herbicide drift also twists and narrows leaves. Zinc shortage shows yellowing between the veins and short internodes over a whole patch. To be sure, soil test for zinc and pH, and a leaf tissue test. In a soil test, less than 0.8 ppm of zinc is low.
What to apply for zinc deficiency
Try a morning spray of zinc sulfate at 2 grams plus calcium carbonate (or lime) at 2.5 grams per liter of water (40 grams in a 16 liter sprayer). Soil zinc sulfate at about 20 kg per hectare on deficient fields. Give zinc sulfate sprays twice two weeks apart. Do not apply zinc and phosphate fertilizer at the same time.
- Zinc sulfate
- Agricultural lime
Sold here with zinc: Harvester Zinc Sulphate Heptahydrate by Universal Harvester (22 percent zinc), Tierramino ZN by Unilox Far East Resources (7 0 0 with 10 percent zinc), Folistim Humi ZN Foliar by Envireau Pacific (10.7 percent zinc and 5.3 percent sulfur) and Omex Zynergy by Jardine Distribution (3.8 percent zinc and 2.1 percent copper). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to fertilizer with zinc, and the page on zinc deficiency in every crop.
To keep it away, avoid heavy phosphorus beyond the soil test, keep pH between 5 and 7.5. Add zinc sulfate to the basal fertilizer where tests show low zinc.
Sulfur deficiency in tomato
It looks like nitrogen shortage but starts on the young leaves at the top. Leaves turn light green to yellow, often more between the veins, and become stiff and curl downward. Stems, veins and leaf stalks can turn purple, and stems become hard and woody. Old leaves may get dead tips and edges with small purple spots. You see it most at this stage: early growth on light soils, and after long rainy periods.
Why sulfur deficiency happens in kamatis
Sandy soils where sulfate washes out, low organic matter, acid soils, waterlogged soils. Long use of fertilizers with no sulfur such as urea and muriate of potash alone.
How to tell it apart
Nitrogen shortage starts on the old bottom leaves. Sulfur starts on the young top leaves. To be sure, soil test for sulfate and a leaf tissue test. In a soil test, less than 10 ppm of sulfate sulfur is low.
What to apply for sulfur deficiency
Switch part of the nitrogen to ammonium sulfate, or use sulfate of potash for the potassium. Try gypsum at 50 kg per hectare in the soil, or a spray of calcium sulfate at 10 grams per liter (160 grams in a 16 liter sprayer) twice two weeks apart. Give sulfur dust at about 25 kg per hectare on sulfur deficient soil.
- Ammonium sulfate 21 0 0
- Gypsum
- Sulfate of potash 0 0 50
- Elemental sulfur
Sold here with sulfur: Crown Champion Ammonium Sulfate by Aqua Hydroponic Prime Ventures (21 0 0 with 24 percent sulfur), Philphos Gypsum (22.2 percent calcium and 17.4 percent sulfur), Harvester Sulphate of Potash by Universal Harvester (0 0 50 with 17.5 percent sulfur) and Agsmart Kieserite Granule (20 percent sulfur and 16.3 percent magnesium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to ammonium sulfate fertilizer, and the page on sulfur deficiency in every crop.
To keep it away, use some sulfur containing fertilizer every season and keep organic matter up. Test the soil every two or three years.
Iron deficiency in tomato
The young leaves at the shoot tips turn yellow between the veins while the veins stay green, giving a net pattern. The leaves are small but not deformed. As it gets worse, the whole tip turns yellow and the leaves can become almost white, veins included. You see it most at this stage: any stage, often after heavy watering or on limed soil.
Why iron deficiency happens in kamatis
High pH, calcareous or overlimed soil, waterlogged soil, and soil high in copper, manganese or zinc. Many Philippine soils are acid and rich in iron, so true iron shortage is uncommon there. Check pH first.
How to tell it apart
Magnesium shortage looks similar but starts on old lower leaves. Manganese shortage also hits young leaves, but more veins stay green and small dead spots appear. To be sure, soil pH test first, then a soil or leaf test for iron. Low potassium can also bring on iron yellowing. In a soil test, less than 4.5 ppm of iron is low.
What to apply for iron deficiency
Try spraying ferrous sulfate at 5 grams per liter of water (80 grams in a 16 liter sprayer) on the leaves. Give ferrous sulfate at about 15 kg per hectare in the soil only where a test shows iron is low. Improve drainage and stop liming. Spray the young leaves in the cool of the day, soon after sunrise or near sunset.
- Ferrous sulfate
- Iron chelate
Sold here with iron: DDDD Planter's Choice Ferrous Sulphate Heptahydrate by Modern Time (19 percent iron), Ferrous Sulfate Monohydrate by Zetryl Chem (30 percent iron), Ferrous Sulphate Monohydrate by Newman Chemicals (30 percent iron) and Liquid Chelate Iron with Sulfur by Sagrex (5 percent iron and 3 percent sulfur). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to foliar fertilizer, and the page on iron deficiency in every crop.
To keep it away, do not overlime, and keep beds well drained. Test the soil every two or three years. Keep organic matter up with compost, manure or crop residues.
Manganese deficiency in tomato
Orange yellow mottling starts between the veins near the leaflet tip and spreads over the leaflet while the veins stay green. Very young leaves show many small dark brown dead spots. Leaves are smaller, sometimes narrow and long, and roots are smaller than normal. You see it most at this stage: vegetative growth and early flowering.
Why manganese deficiency happens in kamatis
High pH or overlimed soil, sandy soil, organic soil, and cold, wet spells.
How to tell it apart
Iron shortage gives a cleaner yellow with no dead dots. Magnesium shortage starts on old leaves. To be sure, soil pH and a leaf tissue test. In a soil test, less than 1 ppm of manganese is low.
What to apply for manganese deficiency
Spray manganese sulfate at 2 grams per liter of water (32 grams in a 16 liter sprayer). A stronger 5 grams per liter (80 grams in a 16 liter sprayer), twice two weeks apart, is also used. Avoid more lime until the pH is checked.
- Manganese sulfate
Sold here with manganese: Manganese Sulfate by Zetryl Chem (31 percent manganese), Turan by SCL Filipinas (11 percent manganese, 6 percent zinc and 2.8 percent copper), Tierramino MN by Unilox Far East Resources (7 0 0 with 12 percent manganese) and Multimate by Agway (4 0 0 with 4.5 percent sulfur, 2.8 percent zinc and 1.8 percent manganese). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to foliar fertilizer, and the page on manganese deficiency in every crop.
To keep it away, keep soil pH near 6 to 6.5 and do not overlime. Test the soil every two or three years.
A soil test is the surest check for any tomato nutrient deficiency. Before you buy, ask your Municipal Agriculture Office where to send a soil sample. The DA regional soil laboratories test soil, and the result says how much of each fertilizer your kamatis needs. That saves money, because extra fertilizer is money lost.
Open the Nutrient Deficiency Finder, pick kamatis, say where the leaves changed first and what you see, and get the fertilizers sold here that fix it.
- Anee, the smart farm technician, reads a photo of the leaf
- The cropping calendar dates every fertilizer application of your season
Tomato nutrient deficiency questions
Why are my kamatis leaves turning yellow?
What fertilizer fixes nitrogen deficiency in tomato?
What fertilizer fixes potassium deficiency in tomato?
What fertilizer fixes calcium deficiency in tomato?
How do I know which nutrient my kamatis lacks?
- Yara US: Nitrogen deficiency in tomato
- Yara US: Potassium deficiency in tomato
- UC IPM: Blossom end rot
- Yara US: Calcium deficiency in tomato
- Yara US: Phosphorus deficiency in tomato
- Yara US: Magnesium deficiency in tomato
- Yara US: Boron deficiency in tomato
- Yara US: Zinc deficiency in tomato
- Yara US: Sulfur deficiency in tomato
- Yara US: Iron deficiency in tomato
Find the missing nutrient and fix it
With Libre + Anee, read the whole guide: how to tell the deficiency from look alikes, how to be sure, what to apply, and the fertilizers sold here that supply it.
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