Caring for Acid-Loving Plants
( adapted from Sheena Adams, GardenWise online )
- Most plants grow best in a pH range close to neutral, with a slight touch of acidity, or 6.5 on the pH scale. Acid-loving plants require an acidic soil around 5.5 in order to take up the necessary nutrients that make them grow, bloom and produce fruit. Popular acid-loving plants include rhododendrons, azaleas, blueberries, potatoes, strawberries and heathers.
- A common sign that plants are planted in too sweet a soil is when leaves or needles take on a yellow-green hue, a condition referred to as chlorotic. Plants become chlorotic when they cannot access nutrients (usually iron or manganese) due to the soil’s high pH level. If a plant struggles too long, it may suffer from death of leaves, dieback of branches and lack of vigour. Left untreated for several seasons, the plant could die. To correct the problem simply lower the pH level and fertilize.
- Determine your soil’s pH using a pH thermometer. If the pH is higher than 6.5, acidify the soil with pine needles, peat moss, bark mulch and leaf mould. Add these to the soil when preparing your garden beds, or use them once a year as a mulch to maintain soil acidity.
- Three times a year, water your plants with leaf mould tea, which will not only lower the pH, but also add potassium, promoting strong root growth, disease resistance and abundant flowering.
- Save your coffee grounds, which are rich in nutrients and tannic acid, and sprinkle them lightly under your plants three times a year to help keep the pH down.
- Recycle leftover pickle juice (vinegar-based), mixing it with 20 parts water and pouring it over the soil. Or simply put all pickle juices, tea bags and coffee grounds into the compost – and be sure to use it often.
- Do not apply mushroom compost/manure to acid-loving plants. This material helps to balance acidic soil conditions, which is useful for roses, but not rhododendrons.
- Since most acid-loving plants are shallow rooted, be sure to add five centimetres of mulch in late fall to protect plant feet from winter conditions.
- Keep lime away from acid-loving plants; an application of three kilograms over 30 square metres will raise the point by one (for example, from 6 to 7, a no-no for acid-loving plants).