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Zinc and sulfur micronutrient · 35.5% Zn · 16.5% S · zinc sulfate monohydrate
About Zinc Sulfate 35.5% Zn
Zinc sulfate monohydrate (ZnSO₄·H₂O) is a water-soluble micronutrient that supplies 35.5% zinc and 16.5% sulfur. It corrects zinc deficiency, which shows as small, narrow new leaves, short internodes that bunch the leaves into rosettes, and yellowing between the veins: as a spray on pecans in spring, a dormant spray on fruit trees, a soil treatment for corn, sweet corn, beans, and onions on a soil test, a leaf spray for vegetables, or a trace addition to a nutrient solution.
Where it goes depends on the soil. On alkaline, sandy, or leveled soils, and soils low in organic matter, zinc spread over the soil is tied up quickly, so trees are treated through their leaves; on field and vegetable soils a broadcast can last two or three years. More is not better: excess zinc is toxic to plants and very toxic to aquatic life, and the powder can seriously damage eyes, so test the soil, stay within the rates on this page, and wear goggles.
35.5% Zn · 16.5% S Zinc sulfate monohydrate, about half again as much zinc per pound as the heptahydrate (23% Zn)
2–3 lb per 100 gal The spring pecan spray in New Mexico State and Mississippi State guidance
1–50 lb bags Seven sizes; the calculator turns your spray tank, trees, bed, or field into an amount and a bag size
Product facts & composition
Analysis and product specifications, Greenway Biotech Zinc Sulfate 35.5% Zn
Specification
Detail
Zinc (Zn)
35.5%, as soluble zinc
Sulfur (S)
16.5%, present as sulfate
Derived from
Zinc sulfate monohydrate (ZnSO₄·H₂O), CAS 7446-19-7, 99% (safety data sheet)
Nitrogen, phosphate, potash
None. This is a zinc and sulfur source, not a complete fertilizer.
Compared with heptahydrate
Zinc sulfate heptahydrate (ZnSO₄·7H₂O) is about 23% zinc, so 1 lb of this product carries as much zinc as about 1.5 lb of heptahydrate
Physical form
White, odorless solid that dissolves in water (safety data sheet)
Hazards (SDS)
Harmful if swallowed; risk of serious damage to eyes; may irritate the skin and respiratory tract; very toxic to aquatic organisms
Shipping class (SDS)
UN 3077, hazard class 9, marine pollutant
Registration
CDFA-registered fertilizer
Package sizes
1, 2, 3, 5, 10, 25, and 50 lb (the 50 lb size may ship as two 25 lb bags)
Packed by
Greenway Biotech, Inc., Madera, California
Percentages are by weight of product: 1 lb contains 0.355 lb (161 g) of zinc and 0.165 lb (75 g) of sulfur. Soil-test reports give zinc as pounds of Zn, so pounds of product = pounds of zinc ÷ 0.355. Several sources on this page write their spray rates for 36% zinc sulfate; this product’s 35.5% is within 2% of that, so use the same weight. Every amount on this page is product weight unless it says “of zinc” or “Zn”.
Best uses & benefits
Choose it when the new growth shows the symptoms and the soil or a leaf test points to zinc. Zinc deficiency looks like iron and manganese deficiency at first, so rule those out; eight common causes of yellow leaves are a place to start.
Pecans
New Mexico State notes that zinc deficiency occurs frequently in most pecan-growing areas and that foliar zinc sprays have become standard practice. Spray new growth in spring, from budbreak, at 2–3 lb per 100 gal; zinc-sufficient trees have bigger leaves.
Apples, pears, cherries, and peaches
“Little leaf” and rosettes on fruit trees call for one dormant spray a year: late dormant for stone fruit, silver tip to green tip for apples, green tip for pears (BC Tree Fruit Production Guide). Zinc sulfate sprayed in summer can injure the trees.
Corn, sweet corn, beans, and onions
University of Minnesota lists apple, dry beans, corn, onion, snap bean, and sweet corn as the crops with the largest response to zinc. On a low soil test, a broadcast or band of zinc sulfate corrects it.
Vegetables with symptoms
Colorado State uses a 0.5% zinc sulfate spray, about 20 g per gallon, to green up plants in season, and treats it as a salvage measure: the soil treatment before planting does more for yield.
Citrus groves
University of Florida IFAS corrects zinc deficiency in citrus with a foliar spray on the spring flush; applied to the soil, zinc is neither an economical nor an effective fix for citrus.
Nutrient solutions
The classic Hoagland solution carries 0.05 ppm zinc, and Penn State’s herb solution 0.13 ppm. A few hundredths of a gram treats 100 gallons, so dose it from a concentrate.
Where it is a poor fit
Soil that already tests adequate. University of Minnesota expects no response above 0.75 ppm DTPA zinc, and NC State warns that soil above 10 ppm may lead to toxicity. Zinc builds up in soil, so test before you repeat a soil treatment.
Soil treatments for trees on alkaline soil. New Mexico State finds most of the zinc in zinc sulfate is tied up in the soil quickly and recommends chelates for soil; Mississippi State uses soil zinc for pecans only below pH 6.0. Spray the leaves, or use Chelated Zinc EDTA.
Yellowing that has not been diagnosed. Iron, manganese, and zinc deficiency can look alike, and high-pH soils often produce more than one; in citrus, zinc and manganese deficiency together are called marl frenching (UF/IFAS). A leaf or soil test tells them apart.
Crops that rarely respond. Colorado State has not recognized zinc deficiency on wheat or alfalfa, and University of Minnesota rates wheat, barley, oats, peas, alfalfa, and grass pasture as small responders.
Phosphate concentrates and recirculating systems. Zinc and phosphate form a poorly soluble compound in concentrated stocks; dissolve them separately. Penn State notes that chelates keep zinc available as pH changes, so use Chelated Zinc EDTA in recirculating hydroponics.
Our complete hydroponic formulas. The crop formulas and Micro Green 2-0-3 already carry zinc; do not add more on top.
Animal feed. This is a fertilizer, not a feed-grade product.
Application rates & directions
Every fertilizer rate below is product weight and names its source, a university Extension service or provincial production guide listed in section 13; the DIY moss and weed amounts at the end are Greenway’s own guidance. A soil or leaf test gives the best rate. Without one, use the starting amounts below only where the new growth shows zinc deficiency.
Weigh it. The density of this product in a spoon has not been measured, so no spoon or cup measure is given. Use a kitchen scale that reads grams for sprays, and convert a zinc rate with pounds of product = pounds of zinc ÷ 0.355.
Without a soil test: starting amounts for plants with symptoms
Zinc sulfate starting amounts where the new growth shows zinc deficiency, for 36% zinc sulfate (use the same weight of this product)
Plants
Amount
How and when
Source
Vegetables, beans, and sweet corn, foliar
0.5% spray: 4.5 lb per 100 gal, or 20 g (0.72 oz) per gallon
Spray the leaves with a surfactant in the cool part of the day; Colorado State uses 20–30 gal per acre, about 0.5–0.7 gal per 1,000 sq ft. Potatoes take a 1% spray, 41 g per gallon
Colorado State Extension
Young (nonbearing) pecan trees, foliar
1–2 lb per 100 gal: 4.5–9 g per gallon
Spray new growth from budbreak, three sprays 2–3 weeks apart in spring
Mississippi State Extension P3055
Bearing pecan trees, foliar
2–3 lb per 100 gal: 9–13.6 g per gallon
Same timing; aim at the undersides of the leaves, which absorb more zinc
Mississippi State P3055; New Mexico State H-602
Home pecan trees, soil (only below pH 6.0)
0.5 lb per year of the tree’s age, up to 10 lb per tree
Once a year; less effective than the sprays
Mississippi State P3055
Apple, pear, cherry, peach, and other fruit trees, dormant spray
1.25 kg per 100 L: 47 g (1.7 oz) per gallon
Once a year: stone fruit at late dormant, apples at silver tip to green tip, pears at green tip; never in summer
BC Tree Fruit Production Guide
Test any spray on a few leaves first. Judge the result on the leaves that grow after treatment; zinc does not move readily into later growth flushes (UF/IFAS). Colorado State notes that sprays green up plants but do less for yield than a soil treatment before planting, and University of Minnesota finds foliar zinc on field crops inconsistent, so test the soil before the next season. This page gives no lawn amount: zinc deficiency in turf is rare, and none of the sources above treat it.
From a soil test: corn, sweet corn, beans, and onions
University of Minnesota zinc rates for field corn, sweet corn, and edible beans by DTPA soil test, converted to this product
DTPA zinc soil test
Broadcast
Band
0.50 ppm or less
10 lb Zn per acre: 28.2 lb per acre, or 10.3 oz (293 g) per 1,000 sq ft
2 lb Zn per acre: 5.6 lb per acre, or 2.1 oz (59 g) per 1,000 sq ft
0.51–0.75 ppm
5 lb Zn per acre: 14.1 lb per acre, or 5.2 oz (147 g) per 1,000 sq ft
1 lb Zn per acre: 2.8 lb per acre, or 1 oz (29 g) per 1,000 sq ft
Above 0.75 ppm
None
None
Minnesota finds that banding low rates gives the greatest economic return on fields that test low, and that broadcast zinc the crop does not use stays available in later years. Colorado State sets one broadcast of 15–30 lb of zinc sulfate per acre, plowed down, as enough for two or three years, then retest. Responses are most likely on fine-textured soils, where topsoil has been eroded or leveled, in cool springs, on calcareous soils above pH 8.3, and after sugar beets (University of Minnesota).
Pecan orchards
New Mexico State mixes 2–3 lb of zinc sulfate per 100 gal of water as a slurry in a 5-gallon can before it goes into the sprayer, and adds 1½ quarts of 32% liquid urea-nitrogen per 100 gal to help the leaves absorb the zinc. Mature trees get about four sprays: at leaf burst, 7 days later, 14 days after that, and 14–21 days after the third; young trees continue every two weeks to the end of July, and new flushes of growth get a spray. Spray from the ground up, because the lower leaf surfaces absorb more zinc. Mississippi State gives bearing orchards 3–6 lb of zinc sulfate per acre and leaf zinc of 60–150 ppm as sufficient; below 60 ppm is low. Above pH 7, New Mexico State uses chelated zinc rather than zinc sulfate in the soil.
Citrus groves
UF/IFAS (SS423) corrects zinc deficiency with a single foliar spray of 2–4 lb of zinc per acre (5.6–11.3 lb of this product), applied to young leaves two-thirds to nearly fully expanded, preferably on the spring flush; 2–3 lb of hydrated lime per acre in the spray reduces the risk of leaf injury. Under severe deficiency, each major flush may need a spray. Applied to the soil, zinc is neither an economical nor an effective correction for citrus. For citrus in a home landscape, Citrus & Avocado Fertilizer 14-4-14 supplies routine zinc with each feeding.
Fruit trees
The BC Tree Fruit Production Guide applies zinc sulfate (36% Zn) annually where leaf analysis shows low zinc: 1.25 kg per 100 L of water, or 16.2 kg per acre (35.7 lb per acre) as a dilute airblast spray, at late dormant for stone fruit, silver tip to green tip for apples, and green tip for pears, before any dormant oil. Cherries can take a second spray of up to 1,000 g per 100 L within two weeks after harvest, never above 86°F (30°C), mixed with nothing else, and without drift onto other crops. Chelated zinc sprays during the season supplement the dormant spray but do not replace it.
Hydroponics and nutrient solutions
Zinc sulfate needed for a zinc target in the final nutrient solution
Target
Per 100 US gal
Per 1,000 L
Source
0.05 ppm Zn
53 mg (0.053 g)
141 mg (0.14 g)
Hoagland and Arnon, Circular 347
0.13 ppm Zn (herbs)
139 mg (0.14 g)
366 mg (0.37 g)
Penn State Extension, modified Sonneveld solution
Grams of product = ppm × liters ÷ 355. These amounts are far too small to weigh on a kitchen scale, so dissolve a weighed amount in a concentrate and dose from it, and keep it out of phosphate concentrates. Hold the solution between pH 5.5 and 6.5, where UF/IFAS reports most elements are absorbed best. In recirculating systems, use Chelated Zinc EDTA.
DIY uses, not on the fertilizer label
These are do-it-yourself uses of zinc sulfate, not uses on the fertilizer label, and the amounts are Greenway’s own guidance rather than from the Extension sources on this page.
DIY: Moss Treatment (Hardscapes Only)
Quick answer: Mix 2–3 oz per gallon and spray evenly on roofs, walkways, and patios. Apply on a dry day; contain runoff away from plants and waterways.
Moss treatment cautions: Use only on hardscapes (roofs, walkways, patios) where runoff can be controlled. Protect nearby vegetation from spray drift and runoff. Avoid discharge into stormdrains, waterways, or aquatic environments — zinc can be harmful to aquatic organisms at elevated concentrations. Test on a small area first to check for surface staining. Follow all local regulations for this use.
Zinc sulfate moss treatment rates by surface type
Surface Type
Application Rate
Method & Notes
Roofs
3 oz per gallon
Spray evenly; contain runoff away from plants and waterways
Walkways & patios
2–3 oz per gallon
Apply and let dry; rinse after 24 hours if needed
Other structures
2 oz per gallon
Test small area first to confirm no surface staining
Expected results
7–14 days
Moss typically browns and detaches; sweep or pressure-wash away once dry
Mix at the rate for your surface type (2–3 oz per gallon). Apply on a dry day with no rain expected for 24 hours. Spray evenly over the moss-covered area. Moss typically browns and detaches within 7–14 days. Sweep or pressure-wash dead moss away once dry. Protect nearby plants and waterways from drift and runoff.
DIY: Spot Weed Management (Non-Crop Only)
Quick answer: 4–6 oz per gallon for broadleaf weeds, 6–8 oz per gallon for grasses. Spot application on hardscape edges only — non-selective at these rates.
Spot weed management cautions: For spot application on hardscape edges and unwanted vegetation in non-crop areas only — never use as a general herbicide near desired plants, lawns, or food gardens. Direct spray contact only. At these concentrations the solution is non-selective. Avoid contact with desired plants and prevent runoff to adjacent vegetation, stormdrains, or waterways. Test on a small area first. Follow all local regulations for this use.
Zinc sulfate spot weed management rates by target
Target
Application Rate
Method & Notes
Broadleaf weeds
4–6 oz per gallon
Spot spray on sunny day; avoid desired plants and prevent runoff
Grass weeds
6–8 oz per gallon
Direct spot application; non-selective at this rate
Eyes, plants, and water. The powder can seriously damage eyes: wear goggles and gloves when weighing and mixing. Stay within these rates, because zinc builds up in soil and excess is toxic to plants. Keep spray, spills, and rinse water out of storm drains, ponds, and streams: zinc sulfate is very toxic to aquatic life.
How to use zinc sulfate
Check the need. Look for small, narrow new leaves, rosettes, and yellowing between the veins on new growth, or white bands beside the midrib in corn. Measure soil pH, and test the soil or leaves where you can; iron and manganese deficiency look similar.
Pick the method and rate. Spray pecans and citrus on new growth, give fruit trees a dormant spray, treat vegetable and field soils by soil test, or dose a stock solution for hydroponics. Use the matching row in section 4.
Measure, then weigh. Measure the spray volume, area, or reservoir, and weigh the product in grams. Wear goggles and gloves.
Dissolve and apply. Dissolve it fully in water, or make a slurry first for a large tank; test a spray on a few leaves, and spray in the cool part of the day. Mix soil treatments into the soil before planting and water them in.
Judge the new growth, then retest. Look at the leaves that grow after treatment, follow the spray schedule in section 4, and retest the soil before another soil treatment; a broadcast can last two or three years.
Calculator & choosing a size
Formulas. From a zinc rate: product (lb) = lb of Zn ÷ 0.355. Area rates: product = rate per 1,000 sq ft × square feet ÷ 1,000, or rate per acre × acres. Sprays: product = rate per 100 gal × gallons ÷ 100. Home pecans in the soil: 0.5 lb × the tree’s age in years, up to 10 lb. Nutrient solutions: grams of product = ppm × liters ÷ 355.
Worked examples. A 3 gal sprayer for beans with symptoms at 0.5%: 61 g (2.2 oz); a 1 lb bag. A 4 gal backpack sprayer for bearing pecans at 2 lb per 100 gal: 36 g (1.3 oz) per fill, three fills a spring; a 1 lb bag. A five-year-old pecan on soil below pH 6.0: 2.5 lb; a 3 lb bag. An acre of sweet corn testing 0.4 ppm DTPA zinc, broadcast: 28.2 lb. A 100 gal reservoir at 0.05 ppm: 53 mg.
What each bag covers at four of the rates on this page
Bag
Vegetable spray at 0.5%
Pecan spray at 2 lb per 100 gal
Fruit-tree dormant spray at 47 g per gallon
Soil broadcast at 10 lb Zn per acre
1 lb
22 gal
50 gal
9.6 gal
1,540 sq ft
2 lb
44 gal
100 gal
19 gal
3,090 sq ft
3 lb
66 gal
150 gal
28 gal
4,630 sq ft
5 lb
111 gal
250 gal
47 gal
7,730 sq ft
10 lb
222 gal
500 gal
95 gal
15,400 sq ft
25 lb
555 gal
1,250 gal
239 gal
0.88 acre
50 lb
1,110 gal
2,500 gal
479 gal
1.77 acres
About the calculator. Choose the job: a vegetable, pecan, or fruit-tree spray, home pecans in the soil, a field or garden from a DTPA soil test, a zinc amount from your soil test, citrus groves (UF/IFAS), or a nutrient solution. It applies the rate from section 4, starting at the low end of a range, shows the zinc supplied and, for sprays, the water to mix it in, and recommends a bag for one application or one spring’s sprays. It works in weights only. Bag suggestions use the current price and stock of all seven sizes, 1 to 50 lb, and the 50 lb size counts as 50 lb. Tax and shipping are added at checkout.
The calculator needs JavaScript. If it does not appear, use the formulas, examples, and table above to choose a size.
How zinc sulfate works
Plants need zinc in small amounts, and a shortage shows as small leaves crowded on short internodes: little leaf and rosette in fruit trees (BC Tree Fruit Production Guide), a broad band of white to translucent tissue beside the midrib in corn (Colorado State), and green bands along the veins on a yellow background in citrus (UF/IFAS). Zinc does not move readily from older leaves into later growth, so each new flush depends on the zinc around it.
Zinc sulfate dissolves into zinc and sulfate ions, so the zinc is in the plant-available form as soon as it dissolves. In soil, zinc becomes less available as pH rises above 7 (NC State) and can form insoluble compounds (UF/IFAS); deficiencies are most common on alkaline and sandy soils low in organic matter, where topsoil has been removed by leveling or erosion, where phosphorus is high, and in cold, wet springs (Colorado State). On field soils, zinc the crop does not use stays available for later crops (University of Minnesota), so one broadcast can last two or three years. On the calcareous soils of New Mexico pecan orchards, most of the zinc in a soil application is tied up quickly, which is why trees there are fed through the leaves and the soil gets chelates.
Monohydrate and heptahydrate are the same compound with different amounts of bound water; this monohydrate carries about half again as much zinc per pound. Effective zinc chelates can be used at about one-third the rate of inorganic sources (Colorado State), and University of Minnesota found all zinc sources except granular zinc oxide equally effective for crops. The evidence on this page concerns zinc sulfate as an ingredient; it is not a trial of this finished product.
Compare your options
Pick by the nutrient a test names and by where it goes: soil, leaves, or a nutrient solution. Analyses are each product’s label guarantee.
Zinc Sulfate 35.5% Zn compared with other zinc and micronutrient options
Option
Supplies
Choose it when
Limitation
Zinc Sulfate 35.5% Zn, this product
35.5% Zn, 16.5% S
Pecan and fruit-tree sprays, citrus flush sprays, and soil treatments for corn, beans, and vegetables on a low soil test
Tied up in alkaline soil; can precipitate with phosphate in concentrates; toxic in excess
Same program is not the same tank. Keep zinc sulfate out of phosphate concentrates, where zinc phosphate precipitates. New Mexico State adds a liquid urea-nitrogen solution to pecan zinc sprays, and UF/IFAS adds hydrated lime to citrus zinc sprays; the BC guide sprays cherries with zinc alone and applies pear and cherry zinc before dormant oil, not with it. Dissolve each product separately, and jar-test any new mix at spray strength; a clear jar does not prove crop safety.
Handling, storage & limitations
Hazards (SDS). Harmful if swallowed; risk of serious damage to eyes; may irritate the skin and respiratory tract; very toxic to aquatic organisms.
Protective equipment. Tight-fitting goggles and gloves when weighing and mixing; a dust mask in enclosed spaces; an eyewash nearby for bulk handling. Do not eat, drink, or smoke while handling it, and wash afterward.
Storage. Sealed original container in a cool, dry, well-ventilated place, out of direct sunlight, away from food, and out of reach of children and pets. Reseal the bag promptly.
Water. Do not empty it into drains. Keep product, spray drift, and rinse water out of storm drains, ponds, and streams, especially during moss treatment and spot weed management. It ships as a class 9 marine pollutant (UN 3077).
Application limits. Only where a deficiency is confirmed or symptoms appear; within the rates on this page; fruit-tree sprays at the dormant timings only. Test sprays on a few leaves first.
First aid (from the safety data sheet). Eyes: flush with water for at least 15 minutes and get medical attention if symptoms occur. Skin: flush with water for at least 15 minutes and remove contaminated clothing. Inhaled: move to fresh air. Swallowed: rinse the mouth with water and do not induce vomiting unless told to by medical personnel. Poison Control: 1-800-222-1222.
Disposal. Dispose of unused product and containers according to local, state, and federal rules.
Frequently asked questions
What is zinc sulfate used for?
Zinc sulfate monohydrate supplies 35.5% zinc and 16.5% sulfur. Growers use it to correct zinc deficiency, which shows as small, narrow new leaves, rosettes, and yellowing between the veins: as a spring spray on pecans, a dormant spray on fruit trees, a flush spray on citrus, a soil treatment for corn, sweet corn, beans, and onions on a low soil test, or a trace addition to nutrient solutions.
How much zinc sulfate do I use on a pecan tree?
As a spray, Mississippi State gives young trees 1 to 2 lb per 100 gallons of water (4.5 to 9 g per gallon) and bearing trees 2 to 3 lb per 100 gallons (9 to 13.6 g per gallon), with three sprays 2 to 3 weeks apart starting at budbreak. In the soil, only where the pH is below 6.0, it uses 0.5 lb per year of the tree’s age, up to 10 lb per tree. Sprays work better than soil treatments.
How do I treat little leaf on fruit trees?
The BC Tree Fruit Production Guide uses one zinc sulfate spray a year at 1.25 kg per 100 liters of water, about 47 g per gallon: at late dormant for stone fruit, at silver tip to green tip for apples, and at green tip for pears. Do not spray zinc sulfate on fruit trees in summer, when it can injure them.
How much zinc sulfate should I use on vegetables without a soil test?
Where the new growth shows zinc deficiency, Colorado State Extension uses a 0.5% spray, about 20 g per gallon of water with a surfactant, at 20 to 30 gallons per acre, roughly half a gallon to three-quarters of a gallon per 1,000 sq ft. Potatoes take a 1% spray. It treats sprays as a salvage measure, so test the soil before the next season; a soil treatment before planting does more for yield.
How do I tell zinc deficiency from iron or manganese deficiency?
All three yellow the tissue between the veins of new leaves, and high-pH soil can cause more than one at once. Zinc deficiency adds small, narrow leaves and short internodes that crowd the leaves into rosettes; in corn it shows as a broad white band beside the midrib. In citrus, zinc and manganese deficiency together are called marl frenching. A leaf or soil test is the reliable way to tell them apart.
Should I use zinc sulfate or chelated zinc?
Zinc sulfate carries more zinc per pound and is the usual dry zinc fertilizer for field crops and foliar sprays. Chelated zinc stays available as pH changes, so choose Chelated Zinc EDTA for recirculating hydroponics and for soil treatments under trees on alkaline soil, where New Mexico State finds zinc sulfate is tied up quickly. Colorado State uses effective chelates at about one-third the rate of inorganic zinc.
Can too much zinc hurt plants?
Yes. Zinc builds up in soil, and NC State notes that soil above 10 ppm may lead to toxicity; in fruit trees, the BC guide notes that zinc toxicity usually shows as iron chlorosis. Test the soil before repeating a soil treatment, stay within the rates on this page, and keep sprays and rinse water out of waterways, because zinc sulfate is very toxic to aquatic life.
Can I use it in organic production or for animal feed?
Greenway Biotech’s zinc sulfate is a CDFA-registered fertilizer and is not OMRI Listed, so check with your certifier before using it on certified ground; certifiers usually require a record of the deficiency for micronutrients. It is not a feed-grade product, so do not use it in livestock minerals or animal feed.
Can I use zinc sulfate for moss treatment or spot weed management?
Published guidance for both uses on hardscapes is available in the Application Rates section above. These are non-nutritional uses — apply only on roofs, walkways, patios, or non-crop areas where runoff can be controlled. For moss, mix 2–3 oz per gallon and spray evenly; results are typically visible within 7–14 days. For spot weed management, use 4–6 oz per gallon for broadleaf weeds or 6–8 oz for grasses — non-selective at these rates. Always protect nearby plants and waterways, test on a small area first, and follow all local regulations. For broader natural weed management strategies, see How to Masterfully Manage Weeds in the Garden.
Is this the same product as the California-restricted roof moss material?
The chemistry is similar — both are zinc sulfate compounds — but the regulatory positioning is different. Our product (zinc sulfate monohydrate, ZnSO₄·H₂O, 35.5% Zn) is sold as a CDFA-registered fertilizer. Materials sold and labeled specifically as roof-moss products carry different label requirements under California pesticide regulations. Use this product as directed on the fertilizer label and the published moss-treatment guidance, follow all local regulations, and contain runoff away from waterways and storm drains.
Articles give background. For this product, use the directions and documents on this page.
Product documents & sources
Product label, Safety Data Sheet, and heavy-metal test results: available on request. Email questions@greenwaybiotech.com with the product name and we will send the current documents.
Where the rates and statements on this page come from
The rates come from the university Extension and provincial publications below, converted to this product’s 35.5% zinc where they give zinc rather than product; they explain plant nutrition and do not certify or endorse this product.
Not sure whether the problem is zinc, iron, or manganese, or which rate fits your trees or crop? Email a photo of the new growth, your soil pH or test, and what you are growing to questions@greenwaybiotech.com or call (562) 351-5168, Monday to Friday, 9 AM to 3 PM Pacific, and we will work through it with you. Every order carries a 90-day satisfaction guarantee, and Standard shipping is free on orders over $100 to the continental US.
Greenway Biotech, Inc. has been a family-owned fertilizer company in California since 1989. This product is packed at our facility in Madera, California, and is a CDFA-registered fertilizer.
5 stars: 32 (80%)
4 stars: 3 (8%)
3 stars: 0 (0%)
2 stars: 2 (5%)
1 star: 3 (8%)
G
Glenn Little
Great service
Got the zink quick and easy
K
Ken Voss
Don’t Know!
Fed Ex lost the package, put in a request for search, still waiting!!!
J
J-P Hsu
product good, packing poor
From past uses in our garden, these amendments seem good. However, the 25# box order of several items had to be taped back together by the post office. The delivery was marked as damaged in transit. The cardboard box was not up to the task. The contents were fine though. The bags are heavy duty enough to withstand PO treatment.
T
Tenny Anderson
Zinc bulk
Very happy
J
John W Weber
Zinc sulfate
No problems with product or packaging.
M
Mark Reitz
Zinc for Pecan Trees
Bag came right away, in good condition.
L
Laurette Crane
Amazingly fast delivery!
This order was processed within a few hours of purchasing online - it was an excellent online purchase experience!
I’ll be using this in my vegetable garden this spring to re-mineralize the soil. Thank you Greenway Biotech!
C
Carl G. Scarbrough
Great Product, Good Price.
Hoping to use in soil this spring for plants. Thanks, Carl
P
Paul Beauregard
This place is a treasure trove
First impressions are lasting and this company was memorable for all the RIGHT reasons. My first order was for Zinc Sulfate in a small bag. The order was packed safely and well, was delivered quickly, and at a good price. I was also pleased with the variety on the website especially for all the plant micronutrients that will help me make up for soil deficiencies in my garden. I will be returning in the spring. Thanks
M
Merritt Garling
It's a bag of zinc sulphate
Price reasonable and shipping rates and speed were great. I'd buy this again.
J
James Rugotska
Zinc Sulfate
It was easy to use. Will have to wait to see the result.
R
ROBERT LANE
Zinc for blooms
Easy to apply, works wonders to get more blooms on Magnolias.
Fast delivery! Overall great experience.
J
James Becnel
zinc sulfate
did not recieve item yet
D
Dennis Irwin
What the F****??
Seriously? Does anyone in your company have a clue? I haven't gotten my order and strongly doubt I ever will since the product was out of stock. Supposedly it was due to you today but of course I haven't heard anything. If I don't hear something positive by the end of the week, I will expect my refund to be processed without delay.
K
Keith Noles
Very good service!
I ordered bulk specialty soil ammendment in 50# packaging and it came well-boxed, in good time, and in good shape. No spills nor tears in bag which was inside of heavy boxing. Assay is as advertised. A very good service that I will use again when I cannot find specialty items that I am looking for. Many thanks!
R
Robin Friedley
Will not be using your product until later in the year.
j
john piccione
the best
super fast delivery, received wiith no issues .....great customer support
B
Bobby Gross
Excellent
Have not used it yet
B
Barry Steinlight
poor packaging bags were leaking
not pleasant working with leaking bags
C
CHARLIE BUSH
great product
awesome fast shipping Thank you
P
Patrick Fox
QUESTIONS
Zinc Sulfate is water soluble. I attempted to dissolve a few grams in distilled water and it left a residue un-dissolved. Why?? and what is this residue chemically?? Patrick, asap.
J
Jorge Morales Scharon
Zinc Sulfate Power
Arrived on time, have not use yet
E
EddieJoe Goude
Excellent
Just what I needed for my pecan trees.
R
ROBERT LANE
Great Product for Trees
I was looking for a solution for my lackluster pecan trees. Seems they need zinc to produce properly. But where to find zinc in a form for plant supplements? Greenway Biotech to the rescue! Finding their website, it was easy to understand the zinc sulfate product instructions and suggestions. Made my purchase easy! Plus, the instructions were both thorough and easy to understand. I will definitely use Greenwayk Biotech products again.
N
Noriko Nishimura
Service; you all rock, Great service.
Am just experimenting with the items...I trust your quality control..
Will give feedback later. Thanks, keep on keeping on.
K
Karen Hollingsworth
previous purchase
It worked very well with my vegetation.
d
daniel t.
Sucks as a weed killer.
Followed your recommendation to use as a weed killer, but it did not work, weeds still growing.
K
Kennie C.
great product
works on pecan trees to prevent zinc deficiency
M
Michael C.
Order of Zinc Sulfate
After a 'rocky' start with the wrong product shipped and delayed delivery of the actual order I have the product I needed. Thank you to the staff who endeavored to correct the mistakes and make my order complete.
I will be doing business in the future with Greenway.
M
Michael T.
Zinc Sulfate
Good Price & Fast Shipping
M
Michele A.
Exactly as described
The product dissolved easy and was exactly what we needed.
F
Fabio B.
Hi there. I didn't received my
Hi there.
I didn't received my products
C
Cynthia N.
Fairly priced, excellent service.
My overall experience was very pleasant. Product was as described, shipping was speedy. Will definitely order again.
My MSM is decreasing my osteoarthritis pain, especially in my hands
My product arrived intact. I started taking it as soon as I went into the kitchen. I mixed it with my daily Metamucil, but there was no discernible taste. I am working on making it a habit each morning. The pain from my osteoarthritis, especially in my hands, is decreasing. I expect it to continue to improve. Thank you for my MSM.
You did not send me MSM Powder, you sent me Magnesium Chloride powder. I tried contacting you 3 times, by email & phone and you didn't have the courage & honesty to return my messages & rectify the situation. I even offered to text you a photo of the mag chloride.
