Mag-I-Cal® Plus for Lawns in Alkaline & Hard Soil
$35.99 – $74.99
- Natural soil amendment for lawns with alkaline soil
- Loosens hard soils
- Promotes air and water penetration for deeper rooting
- Helps to rapidly lower soil pH to increase nutrient absorption
Real Mag-I-Cal Plus Alkaline Lawns
Product Overview
Mag-I-Cal® Plus for Lawns in Alkaline & Hard Soil contains sulfur and gypsum which lower soil pH, is important to cell development, and is vital to many grass plant functions.
Additionally, Mag-I-Cal Plus® for Lawns in Alkaline & Hard Soil helps to break up clay and compacted soils. When soil is compacted or too alkaline, air, water, and nutrients are unable to reach the roots, making it very difficult for grass to flourish. This soil conditioner improves root penetration and promotes growth by increasing biological activity and releasing nutrients trapped in the soil.
Coverage Guide
For soils with a pH over 7.5, use the new lawns rate.
Coverage:
Shipping & Returns
Shipping
- Free ground shipping now available on orders of $75 or more! For smaller orders, shipping costs are calculated at checkout.
- We ship orders the same day if placed by 2PM EST (later orders will be shipped the next day).
- Orders are not shipped or delivered on weekends or holidays.
- We offer ground and expedited shipping.
Returns
- We offer 30-day free returns for replacement or full refund for items that are damaged or defective (shipping included). If damaged by the carrier, please file a claim with them.
- If your items have been used or aren’t in the original packaging, we will give you a refund (minus the cost of shipping) based on the condition of the product.
View our complete shipping and return policy. If you have questions about your order, please contact our customer service team at [email protected].
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Where to Apply
This product can be applied throughout the United States and performs well on both cool and warm-season lawns.
When to Apply
For cool and warm season lawns, apply in either spring, summer or fall when air temperatures are at least 45°F.
Active Ingredient(s)
Calcium, and sulfur (Derived from: Calcium Sulfate Dihydrate(gypsum), Ammonium Sulfate, and Sulfuric Acid.
Also contains non-plant food ingredients: humic acid (derived from humus), polyhydroxycarboxylic acids (derived from plant extracts).
Use With Other Products
Mag-I-Cal® Plus for Lawns in Alkaline & Hard Soil contains natural ingredients and can be applied with any of our grass seeds, weed controls, fertilizers, and insect or disease controls.
How Often to Apply
- For a pH of 7.0 to 7.5
Apply Mag-I-Cal® Plus for Lawns in Alkaline & Hard Soil once per year.
- For a pH over 7.5
Apply Mag-I-Cal Plus for Lawns in Alkaline & Hard Soil twice per year (at least one month apart).
Safe for Children & Pets
Mag-I-Cal® Plus for Lawns in Alkaline & Hard Soil is a natural product, meaning it is safe for children and pets to re-enter the lawn immediately after application.
Precautions & Proper Handling
- Carefully read all instructions prior to application.
- Store in a cool, dry place away from children and pets.
- Do not ingest. May cause irritation to eyes and skin.
- Wash hands thoroughly with soap and water after handling and before eating or drinking.
- Do not apply near water, storm drains, or drainage ditches.
- Do not apply if heavy rain is expected.
- Apply this product only to your lawn or garden and sweep any product that lands on the driveway, sidewalk or street back onto your lawn or garden.
Product Label
Always read and follow the product label before use.
Safety Data Sheets can be found at www.jonathangreen.com/safety-data-sheets-sds. If you have a specific question, do not hesitate to contact us.
Manufacturer
Spreader
Model
Rate

How do I test soil pH?
You can test your soil’s pH by sending a soil sample to your state university cooperative extension office, who will send it off to a lab for a small fee, or by using an at-home testing kit.
To perform a soil pH test with the Jonathan Green Soil pH Test Kit, follow these steps:
1. Collect soil samples from your lawn
Gather small soil samples from four different sections of your lawn by using a gardening trowel to dig four to six inches deep into the lawn’s surface. Mix all four small samples together for one, cohesive sample to use for your test. Make sure to remove all debris from your sample and proceed to the next step.
2. Fill test container with soil sample
Once you have your comprehensive soil sample, remove the cap off of the color comparator and take out the capsule. Make sure the pH color chart is in place, then fill the test container with your prepared soil sample. Carefully separate the two halves of the capsule and pour the contents into the test container.
3. Add distilled water to the test container
Using the provided dropper, add distilled water to the test container. Do not use tap water for your soil pH test, as it usually contains acidic or alkaline components.
4. Shake test container and allow to settle
After adding distilled water to the test container, shake thoroughly and allow the test container to settle for one to five minutes.
5. Observe test container for results
Can I use your products in my garden?
Yes! Our soil amendment products (Mag-I-Cal® for Lawns in Acidic Soil, Mag-I-Cal® Plus for Lawns in Acidic & Hard Soil, Mag-I-Cal® Plus for Lawns in Alkaline & Hard Soil, and Love Your Soil®) are all great to use in the garden.
How to take a soil sample
Steps to take a soil sample
- With a shovel or a spade* dig a V-shaped hole to sample depth of 4-6 inches (excluding any thatch), then cut a thin slice off to the side.
- Do this in 4 or 5 places in the section of the lawn to be tested.
- Mix soil samples together in a clean, plastic bucket. If the bucket has been used to hold fertilizer or other chemicals, wash it thoroughly before using it for soil samples.
- Let the sample dry well before testing. Place it in a ziplock bag or coffee can. Approximately one quart is recommended.
- Make sure to use distilled water for testing.
*Tools should be either stainless steel or chrome-plated. Do not use brass, bronze, or galvanized tools because they will contaminate samples with copper and/or zinc.
Features You’ll Love
Combat Alkaline Soil

Soften Hard & Compacted Soil

Safe for Kids and Pets

How to Apply
Prepare
Test Soil
Test your soil pH to check that it is in a healthy range for grass plants to grow. Optimal pH for cool-season lawns is 6.2 to 7.0.
Rake
For best results, rake the lawn vigorously prior to application to remove debris and thatch.
Apply
Set
Use a spreader suitable for your specific lawn size. Set the spreader according to the recommended setting on the packaging or use our Spreader Settings Tool above. Make sure to update the setting with each product you apply.
Spread
Begin by spreading along the perimeter of your lawn. Make straight passes back and forth across the length of the lawn in a mowing pattern until the entire area is covered. Overlap slightly between passes and close the hopper when turning. Walk at a steady pace for even distribution.
Sweep
To avoid staining, sweep any excess granules off of hard surfaces and back onto the lawn or garden.
Maintain
Water
Irrigate the treated area after application for 15 – 30 minutes for the best results.
Mow
Once watered, wait at least one day to mow the lawn to give the product time to activate.
Re-apply
For soils with pH higher than 7, repeat applications twice a year.
