Can I Cover Cannas With Ashes?

Canna Cultivation

• The boldly glamorous canna thrives in heat and humidity; as a result, it is more common in southern gardens than in cooler, northern climes. However, those who live in U.S. Department of Agriculture hardiness zones 7 through 9 can easily cultivate cannas by simply covering the bulbs with wood chips, pine needles or wood ash at the end of the growing season. The materials insulate the soil and protect the bulbs from the destructive effects of winter weather. You can grow cannas north of zone 7, but you must dig up the bulbs and store them in a dry, cool location for the duration of the winter.

Wood Ashes

• Prior to being set on fire, wood ash is just wood. While the fire does remove some of the nutrients naturally found in wood fibers, the ashes still contain potassium, magnesium, calcium and other beneficial elements. Incorporating leftover wood ash into the soil improves its structure, increases its fertility and costs nothing. Additionally, wood ash raises the pH of the soil, decreasing the acidity. While the shift in pH is temporary, it can improve the growing conditions for alkaline-loving plants, such as cucumbers, lilacs and hydrangeas.

Ash Application

• To feed garden plants, spread a 1/2-inch layer of wood ashes over vegetable patches and flowerbeds, and around the bases of deciduous trees, fruit trees and shrubs. Once you have evenly distributed the ashes, work them into the surface of the soil with a garden rake. Incorporating the ash into the soil increases the rate of decomposition and encourages nutrient dispersal. To insulate bulbs, such as cannas, for winter, spread a 2- to 4-inch layer of ash over the bulb bed in late fall. Should the weather drop below freezing, the thick blanket of ash will keep the ground warm and shelter the bulbs below. Remove any remaining ash in the early spring when all danger of frost has passed.

Warning

• Do not use wood ash on alkaline soils or near acid-loving plants, such as roses, azaleas, blueberries, evergreens, rhododendrons and camellias, as the drop in acidity can be detrimental to their growth. Be sure to add wood ashes in autumn or winter, rather than spring; fresh ashes contain a number of compounds that can inhibit the growth of young seedlings.