Many gardeners and homeowners may be surprised to learn that the health of many plants can be tied back to the health of the soil and its relative acidity. The acidity of soil is measured on the pH scale, which ranges from 1 to 14, one being the most acidic, 14 being basic (also called alkaline) and 7 being neutral. Most living things must stay close to a seven on the pH scale, but the majority of plants actually grow best in slightly acidic soil at a pH level of 6 to 6.8. For gardeners, the pH scale runs from about a 4 to an 8, with little plant growth beyond either end of the spectrum.
The pH scale is logarithmic, meaning that soil with a pH of 6 is ten times more acidic than a neutral seven, and that a pH of 5 would be a hundred times more acidic than a seven! The best plants for slightly acidic soil are many and easy to find, but finding the best plants for acid soil in the pH range of 4.5 to about 6.5 can be difficult without the right information.
Shrubs for Acid Soil
Wintergreen is among the most popular shrubs and best plants for acid soil, growing well in a pH range of about 4 to 6.5. The large aromatic bush remains green throughout winter and is also capable of withstanding hot summers. Trailing Arbutus provides groundcover with its creeping deep green growth and white flowers. Arbutus requires intensely acidic soil around a pH of 4.5 and is one of the best plants for very acid soil; however, it is difficult to grow in a pH over 6. Heather is another popular groundcover shrub with cheerful purple flowers that grows well in a pH of 4.5 to 6. Azaleas and Rhododendrons are among the most well-known flowering shrubs and grow very well in a wide range of acid soil from 4.5 to 6. However, not all plants will grow in all climate zones, regardless of the level of acidity. Refer to a zone chart here.
Trees for Acid Soil
Acidic soil is excellent for almost all evergreen trees, including Pines, Firs, Spruces and Yews. Evergreen trees grow best in an acidic soil with a pH in between 5 and 6. Sweetbay Magnolia grows in an even lower pH- about 4 to 5, while Holly trees grow best in a pH of 5 to 6. Many types of oak trees, like Pin Oak or Red Oak, do poorly in soil of a high pH (above 7) and prefer acidic soils around a pH of 5. Weeping willows, Dogwood and Crabapple trees also flourish in soil with a pH from about 5 to 6.5.
Flowers for Acid Soil
Some of the most beautiful flowers prefer their soil very acidic, including Bleeding Heart (5-6.5), Foxglove (5.5-6.5) and Columbine (5.5-7, depending on the many varieties) and most ornamentals in general grow well in slightly acidic soil. Roses grow well in soil of slight acidity, but can also be made to grow well in soil with a pH just below 6. Amaryllis, Phlox, Zinnia’s and Pansy’s all do well in soil with a pH as acidic as 5.
Vegetables and Fruits for Acid Soil
Most edible foods grow best in only slightly acidic soil from 6 to 6.8, but can also do well in soils as acidic as a 5. Cherry, Peach, Apple and Pear trees grow best in soil from a 6.5 to an 8 but will perform relatively well on average in a pH as low as 5.8. Despite the shortcomings of fruit producing trees, one of the very best plants for acid soil is the Blueberry Bush. With even more acidic tastes than most plants, the blueberry bush grows best in a pH of about 4 to 5 and will have difficulty producing fruit in soil of a higher pH. Kiwifruit, Huckleberry, Potatoes and Crabapple are all delicious foods that grow best in acidic soils between 5 and 6. Most vegetables have no problem growing in acidic soil and will perform well and produce healthy, tasty foods for your dinner table or local farmer’s market.
Areas with Acid Soil
Acid soil is most common in places that experience heavy rainfall and have moister environments. Areas in red have acidic soil, areas in yellow are neutral and areas in blue have alkaline soil.
Testing and Changing Your Soil’s pH
Most garden and hardware stores provide cheap soil testing kits that make testing the pH of your soil easy. Be sure to test your soil in various areas, so you can more properly gauge the overall acidity of your soil. Once you know the pH of your soil, you can either select the plants that will grow best in acid soil or in alkaline soil, or you can attempt to raise or lower the pH to accommodate other plants. It is highly recommended that you test your soil before making any pH changes.
To make acidic soil, mix equal parts Canadian peat and soil together and add a half to a quarter parts sand. Peat is very acidic, so be sure to test the soil mix and alter as needed. Add limestone to raise the pH level of your soil and lower the acidity. You can also lower the pH and make your soil more acid by adding nitrogen based fertilizers, like manure or urea with caution. Adding large amounts of manure over the years can make your soil so acidic that the plants will be unable to access necessary nutrients for years to come. For more information on liming your garden or otherwise altering the pH, go here.
Acid Soil and You
bob_redbuick on April 22, 2012:
Great article and and responses. I'd like to learn how to check the pH in a garden, say 25 by 50ft. How deep do I take a composite sample or samples? Most of my yard is mildly alkaline. I plan to plant some acid loving plants.
Any suggestions on where to obtain a fairly complete list of plants ,bushes, and trees including fruits and veggies, that prefer soil less than pH of 7.0. My hardiness zone is 7 in central west Oklahoma. Thanks
Shanna (author) from Utah on March 15, 2012:
Thank you all for the encouraging comments and votes. :)
Nithya Venkat from Dubai on March 14, 2012:
Great hub with a lot of useful information. Gardening is a very good hobby to be encouraged specially with kids. Voted up.
Rachel Vega from Massachusetts on March 07, 2012:
Ohh, those pictures are so pretty! It almost makes me want get my hands dirty Thanks. Got my Beautiful vote and UP!
Simone Haruko Smith from San Francisco on March 07, 2012:
Fantastic suggestions. It's nice to know that one needn't have a lackluster garden even if the soil is a bit on the acidic side. Gosh, Bleeding Hearts are beautiful!
Alissa Roberts from Normandy, TN on March 03, 2012:
Such an interesting and informative hub! I was wanting to start a garden in the backyard this year so this will be most helpful. I will be sure to test out the pH levels to ensure a successful batch of homegrown goodies. Thanks for the info - voted up, useful, and interesting!
Cholee Clay from Wisconsin on March 03, 2012:
This is a great hub! Very informative and well written. My dad is constantly adding gardens to the yard. In a couple years I'm sure we'll have no yard left as he will have turned it all into a garden.
Even within our yard there are spots where certain flowers won't grow, maybe due to a slightly different pH level? Roses and Bleeding Hearts grow great in the front gardens but trying to plant them in the backyard only seems to kill them.
Rebecca Mealey from Northeastern Georgia, USA on March 03, 2012:
I like the way you organized the Hub and included the areas map. Very interesting!
Dreamer at heart from Northern California on March 03, 2012:
I grew Blueberry plants in Oregon and enjoyed the bountiful harvest from three bushes for over 10 years. These are a wonderful addition to the landscape too! I wrote an article here about diamonds in my garden.
Cynthia Calhoun from Western NC on March 03, 2012:
Great read here! I have azaleas and rhododendrons growing all over the place where I live - acid soil galore! It's interesting to see that map, too, because the breadbasket (the midwest) of the US is neutral soil. I grew up in Colorado with clay soil and had to learn the hard way why certain plants would die in my yard. Now, I have one big obstacle: a black walnut tree. So many things won't grow near that thing but, my violets thrive under it. Great hub! Voted up, U/I.
cardelean from Michigan on March 02, 2012:
This is a fantastic guide. I have not tested my soil and will have to do that this summer. I plan to really expand my garden this year and this will be very helpful in making the correct adjustments in choosing the right plants.
Shanna (author) from Utah on March 02, 2012:
Melbel- I'm jealous! I wish I could continue gardening, but since I moved out and into a dorm (soon to be apartment) I can do very little in the way of gardening. Plant something for me, will you? :)
leahlefler- Thank you! I actually had to add more peat moss to my soil-- it was a bit too alkaline for my raspberry patch.
Teresa- Thank you very much! Before I learned about how important the pH level of soil was, I killed a lot of innocent little plants.
DIYmyomy- Thank you very much! I wish things were waking up here in Utah... but it's going to be cold for a while longer, unfortunately.
DIYmyOmy from Philadelphia, PA on March 02, 2012:
Thanks for this very informative article! Good timing as well, as my gardens here in SE PA are just beginning to wake up. Voted it up and as useful.
Teresa Coppens from Ontario, Canada on March 02, 2012:
Very informative hub Shanna. I think for the next growing season I need to test my soil and figure out why certain plants aren't growing well in some areas. I may have to do with soil pH. I have lots of horse and chicken manure living on a farm. It is great when composted for all my plants but I never thought of it as a soil conditioner for altering pH. Great job!
Leah Lefler from Western New York on March 02, 2012:
Great hub, Shanna - this is a good reminder for me to plant bleeding heart this year. I've been meaning to do it for a while - I love that flower! We have fairly acidic soil, but I usually have to amend the soil for our rhododendrons. Columbine is on my "to plant" list as well, because the deer usually leave it alone!
Melanie Shebel from Midwest, USA on March 02, 2012:
This is really cool! We have acid soil in our yard -- it's a mixture of dirt, then clay, and then sand. I didn't think about particular things I'd have to grow... which is a really good thing since I plan on doing some heavy gardening this year.