Popular plants such as azaleas, rhododendrons, blueberries, strawberries and heathers, are all acid-loving, meaning they need a soil pH of about 5.5.
While many garden plants are adapted to a fairly wide range, certain plants—like azaleas, rhododendrons, hollies, and blueberries—are fussy about having acidic soil.
Acid-loving plants are those that prefer a soil pH below 7. The pH, or potential hydrogen ions, in soil can range from 0 to 14. Seven is considered neutral, and anything below 7 is acidic. Soils with a pH over 7 are alkaline.
Basil likes rich, moist, but well-drained soil with a pH of 6 to 7.
Tomato plants will grow well in well-drained sites that receive full sun for most of the day. The soil pH should be slightly acidic (6.2 to 6.8). Excess nitrogen can result in plants with lush, vigorous foliage but little fruit production.
Compost soil, coffee grounds, stale beer, tea, or mineral water are all excellent choices. These natural fertilizers provide essential nutrients for your basil, promoting healthy growth and blooming.
Contrary to popular belief, it's a myth that coffee grounds are acidic and will lower the pH of the soil. After brewing, the grounds are close to pH neutral, between 6.5 and 6.8. Research shows that whatever change coffee grounds bring to the soil is short-lived, Brewer said.
For true blue hydrangeas, the plants need to be grown in acidic soil with a pH of 5.5 or lower. For pink flowers, the plants need neutral to alkaline soils (pH 6.5 and higher). For purple blooms (or a mix of blue and pink flowers on the same plant), the pH of the soil must be between pH 5.5 and 6.5.
A general rule is applying a ratio of one part coffee grounds to three parts soil. Lemon juice: Since lemons are naturally acidic, they can be used to increase the acidity of your soil as well. You can use the peels or the juice of the lemon.
The ideal pH range for hostas is 6.5–7.5, which is slightly acidic to slightly alkaline. In higher pH soils, the addition of organic matter such as Canadian peat moss and cottonseed meal will tend to lower the pH. The planting hole should be dug at least a foot deep.
Peat is naturally quite acidic (pH 3.5-4.5) so lime must be added to raise the pH. Off the shelf potting soil always contains lime. The amount of lime that must be added depends on the composition of the peat. For example, garden peat always needs more lime than peat litter to raise the pH.
Marigolds prefer a slightly acidic soil. However, at a soil pH below 5.5, marigold leaves may develop a bronze speckled appearance due to manganese or iron toxicity. In the absence of soil test results, a slow-release fertilizer formulated for annuals can be incorporated at the time of planting.
If you've been trying to get your hydrangeas to become big and blue, then we might just have the tip for you. Hydrangeas color is based on how acidic your soil is—the more acidic the soil you plant your hydrangeas in, the more blue. We've found that adding a few coffee grounds to your soil can do just the trick.
Roses require a pH of near 6.5.
Roses can cope with the soil being slightly higher or lower than 6.5, but may not grow well. If the soil is too acidic it may not grow at all. If the pH in the soil is incorrect, roses will show signs of stunted growth, yellowing foliage, burnt shoots, die back and in some cases, death.
If your hydrangeas are getting too much sun, too little water, or the wrong type of nutrients, those pretty petals can turn pale.
The calcium from eggshells is also welcome in garden soil, where it moderates soil acidity while providing nutrients for plants. Eggshells contain such an abundance of calcium that they can be used almost like lime, though you would need a lot of eggshells to make a measurable impact.
Prevent Fungal Disease
MAKE IT: Mix 1 teaspoon of baking soda and 2-3 drops of liquid soap in 1 liter of water. Spray the solution on the infected plants. Baking soda helps the plants become less acidic and prevents fungal growth.
Coffee grounds can most certainly be added to your compost and also directly to your soil. Instead of simply tossing them out though, you may wish to incorporate them a bit more thoroughly by digging them in.
Avoid using coffee grounds on alkaline-loving trees, such as linden, ironwood, red chestnut and arborvitae. Coffee grounds used as mulch or compost inhibit plant growth on geranium, asparagus fern, Chinese mustard and Italian ryegrass. Definitely don't use coffee grounds with these plants.
Lavender: This herb thrives in slightly alkaline soil and can suffer in acidic soil. Rosemary: Similar to lavender, rosemary prefers a more neutral to slightly alkaline soil and might not do well with coffee grounds.
How often can I put coffee grounds on my tomato plants? A sprinkling of coffee grounds mixed into the soil before planting tomatoes will not harm the plants. However, no additional coffee grounds should be added to the soil during the growing season.