The right soil pH is crucial for the health of your plants. It is one of the primary things that can determine how well your plants absorb the nutrients they need to survive and thrive. Most plants do best with a pH between 6.0 and 7.5, but research the plants you are growing specifically to see what they need. A soil test can help you learn your current pH levels.
How to Alter the pH
Once you know if you need to increase or decrease the acidity, you can take steps to organically alter the pH in your soil. Here, we will look at what to do if your soil is too acidic, or, in other words, what to do if you need to raise the pH.
- Test your soil. This will help you determine how much you need to raise the pH. You can get your soil tested through your local extension office or with a soil test kit you can buy at most garden centers.
- Determine what you will use to increase soil pH. You have a couple of options to organically raise the pH in your soil.
You can use limestone, which is one of the most common ways to raise pH. The amount you use will vary depending on your soil’s needs, but typically, these are the amounts of limestone to use for different soil types:
- Sandy soils: 2 pounds per 100 sq. ft.
- Loamy soils: 3 ½ pounds per 100 sq. ft.
- Clay soils: 5 pounds per 100 sq. ft.
Be careful not to use too much, as lime can have adverse effects, like burning the plants.
You can also use wood ashes. This can raise the pH quickly but does not have as long-lasting effects. You will want to use ¼ inch of wood ash on the soil surface, then follow steps 3 and 4 below.
Be careful to not use ashes from chemically treated wood, and ensure that the ashes are dry. There are certain plants you will want to avoid using ashes on as well – like blueberries and azaleas, which love acidic soil. And try to avoid the ashes coming into contact with germinating seeds.
You can use baking soda, too. This is a cost-effective method that is quick and easy to do. Baking soda also does not last as long as lime (similar to the ashes) but can produce results in just a few days. Baking soda is fairly gentle on both the soil and the plants, so you won’t have to worry about harming your plants.
Mix a tablespoon of baking soda into a gallon of water. (You can use this ratio to increase or decrease the amount you need, based on the size of your garden.) Be careful not to add too much baking soda or use too much of this mixture in your garden, as it could create an imbalance. You can do this every few months as needed to maintain the optimum soil pH.
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3. Mix the amendment of choice into the soil.
Once you have chosen an amendment and measured it out according to your needs, you will need to mix it into the soil thoroughly. You can do this with a rake, a shovel, a tiller, etc. Ensure the amendment is well mixed into the top 6 inches or so of the soil, so that it can really make the changes you are hoping to see in the pH.
4. Water the area well.
You will need to water the area very well, ensuring that it can reach a depth of at least 6 inches. This helps to activate the amendment so it can begin its work. You will want to water the soil regularly, but avoid overwatering as that can have adverse effects like leeching minerals and nutrients out of the soil.
5. Test the pH again after a few months.
Every few months, you will want to retest the soil to check on the status of the pH. This can help you learn if you used the correct amounts, and if it is still working (as different amendments can last different lengths of time).
Limestone takes longer to break down, so it will last longer than baking soda or wood ashes, but also may take longer to see the effects of the pH being raised. You may need to apply your amendment(s) again. If you do need to apply another round of limestone, you can do so in the fall. The other amendments can be done when/as needed in spring or fall.
pH levels can be affected by rainfall, fertilizer, and other changes in your yard’s conditions, so regular testing can help you catch pH problems before they cause issues for your plants
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I’m about a month into gardening (zone 9) and I tested the ph in my strawberry plants. The reading came back too alkaline (7.2 ish) reading your suggestions I will try the baking soda method!!
Hi Chelsea, we are glad to hear that you tested the ph for your strawberry plants. After re-reading your comment and with the help of some other commenters we realized we read it wrong, we were stuck on raising soil pH. Baking soda will raise your pH not lower it, you need to lower your pH for strawberries they like a pH between 5.5 to 6.5, you can use sulfur or Aluminum sulfate to lower your pH.
If you are trying to lower ph why would you use baking soda? Baking soda would raise your ph even higher.
Thanks for the valuable ph info. I knew it was important, pH, but I didn’t realize how important it was.
I recently accidentally just about liquified several of my aloe veras by transplanting them into acidic soil. I assume it’s the ph change that damages them—the soil I transplantes into is a mixture of mostly sphagnum moss, with some organic soil.
I understand sphagnum moss typically has a ph of 6 to 6.5. Is it possible to render a good alkaline soil out of this by adding a solution of baking soda and water? Or is sphagnum moss just so acidic that it will pull the ph back down?
Hi David, luckily aloe rebounds better than most plants so once you get them in the ideal growing environment they should bounce back. Aloe is tolerant so if your soil is slightly too acidic or too alkaline it will survive, making sure that is in well-draining soil and gets full sun will help with this. Knowing what the pH of the soil is would be your first step so actually testing the soil would be recommended. You can learn more about testing in this article. https://www.kellogggarden.com/blog/soil/how-and-when-to-test-your-soil/ Aloe likes soil that has a pH of 7.0 to 8.5. Peat moss is actually acidic, sphagnum moss is more neutral. Once you know what your pH is then you can adjust it up or down.
I used the run off water then tested it and it came back 6.0 is that ok for ? and herbs plants
Hi John, tomatoes can thrive in soil that has a pH between 5.5 and 7.5 and most herbs can tolerate a soil pH ranging from 6.0 to 7.0. Therefore, you should have no problems using your water runoff that has a pH of 6.0. Happy gardening!
Hi, I require a ph of at least 8.8 for s class project. How can I get my soil up to scratch? I have wood and matches.
Hi Jasper, we recommend using dolomitic limestone to raise your pH levels.
Have just purchased a beautiful pink geranium (white neater with deep red, pink border) not sure wether to plant in soil or pot, am worried that it will change colour no matter where I decide to plant it. Do I have to make sure the soil is alkaline for planting.
Hi Julie, depending on what type of geranium you purchased it will prefer different pH levels in the soil. For example, Zone Geraniums grow best in a soil pH between 5.8 and 6.3, and Ivy and Regal Geraniums enjoy soil with a pH between 5.5 and 6.0. Generally, the soil pH will not impact the color of your geraniums. Geraniums don’t typically change colors, but if they do it is likely caused by a mutation in the flower and not the growing or soil conditions. Geraniums are commonly grown in containers but can be planted in-ground as well. They prefer moist, well-draining soil and to be planted or placed in a location where they can receive 4 to 6 hours of sunlight daily. Different geraniums have different planting and care requirements, therefore, we recommend researching your particular variety. We hope this helps, happy gardening!
I have new grass in a pine area…high acid I guess…it is turning yellow…do I need a quick fix like wood ashes and/or lime?? Thanks
Hi Anne, pine can bring up the acidity level of your soil, first thing to do is test your soil to see where your pH level is at now. You need at least a pH of 6 to grow healthy grass. Once you know your pH level you can add in limestone to bring your levels up, it takes approximately 5 pounds of limestone per 100 sq ft. to raise the pH one point. For wood ash it takes approximately 2 pounds per 100 sq. ft. You can add the lime or wood ash to a fertilizer spreader to administer it. Test soil after administering to make sure you are at the optimal pH. Adding compost to your soil is also a good idea. It can be difficult but raking and removing pine needles as often as possible will help keep your pH from falling too quickly. Having grass in a pine area means you will most likely need to watch that area and amend your soil as needed.
Hi, I just bought new soils (3 in 1 ) in large quantity and just started my drawf fruit tree garden in big pots and I have 15 large pots with all sorts of young fruits tree just planted about a month now. I just used a PH tester and realized all of the PH falls u ter 4.5-5.5 only …
The trees are surviving with those fruit not really growing …. I just purchased and put dolomite lime around the pot this evening and know that it is slow in altering it . Can I put Baking soda by tomorrow already ??
Hello Lilian,
Most fruit trees like a soil pH between 6 and 6.5 but make sure to check the pH levels for the specific varieties you are growing. Your comment doesn’t say where you are located, how old the trees are, and whether you added fertilizer when you potted them. Your lack of growth could be due to a nutrient deficiency, age, transplant shock, as well as other factors. You may want to contact the seller of the fruit trees for assistance, they will know more about the history of the trees and can offer some advice to help you.
Surface application of lime is likely to change pH in only the top inch of the soil, scratching it into the soil may be required to raise soil pH faster. Have you watered yet? Lime reacts slower in dry soil, but be careful watering too much it can leech other essential minerals out.
A day is not enough time for lime to do its work so you may want to wait a bit longer like 3 – 5 days and check again. If you really feel you need to add some baking soda to water and water your trees, do it in smaller quantities so you don’t raise your soil pH too high, especially once the lime starts to kick in you may find yourself with pH levels that now need to be lowered.
Hello. What is the ideal ph levels for Gardenias and Tibuchinas? I have both planted in pots with well draining moisture control soil. Would the baking soda be the best alternative if according to my reader they both show low ph? Thank you in advance
Hi Liz, gardenias and Tibouchinas prefer more acidic soil with a pH between 5.0 and 6.5. Any of the methods discussed in this blog, adding limestone, wood ash, or baking soda will work great if you need to raise the pH of your soil. If you have any additional questions, we’re happy to help.
Great article! I bought some hydrated lime to raise my ph in my clay soil. It is the only kind that I could find. If I mix some with water, how much would I use in my trees? My tester says 4.5 so I need to raise it one or two points for my newly planted fig trees. I’ve read that hydrated lime could kill plants so would I be better off using baking soda? My other tests seem to show I have high potash and maybe calcium in my clay soil. Also my well water ppm is off the charts and when I water potted plants they seem to go down hill but my newly planted figs are starting to grow, I’ve been given them mg tomato fertilizer and it seems to be OK. Aslo My newly planted grape vines (this yr) have not grown a bit but they’re still alive, so far I’ve tried kelp, mg, fish fertilizer and added Gypsum but nothing seems to be working? Thank you for your great advice!
Raising your pH to about 6 will be good for both the fig trees and the grapevines. For the hydrated lime we would recommend contacting the company that makes the product for application rates. They would have a more informed answer since they make it. Clay soil can be difficult to grow in not just because of pH and nutrient concerns but also drainage. Figs and grapes like well-draining soil, did you amend your clay soil to create optimal drainage? We have soil products, that can help create better drainage in clay soil. There is a store locator box on the product page that will tell if those products are available in your area. Also adding organic matter through compost and sand can help with drainage.
https://www.kellogggarden.com/products/gborganics/gb-organics-soil-building-conditioner/
https://www.kellogggarden.com/products/kellogg/amend-garden-soil-for-flowers-and-vegetables/
Grapevines need nitrogen and potassium to really thrive, it sounds like the potassium levels are not low, for the nitrogen you can use blood meal or composted manure to give you more nitrogen.
Can green bioslurry improve or decrease soil pH?
Hi Moses, Green Bioslurry is not a product we are familiar with using. Based on our research, it can be beneficial. However, since it is homemade, it is difficult to say whether it will increase or decrease the pH.
I need to raise my ph by half to a full point. If I add the baking soda how long will it take to raise it and also how long does it keep the ph at that level
You should see a change within 24 hours. As you water it will break down so you may need to keep applying throughout the season.