Wood ash is rich in nutrients that plants thrive on. It may seem that all plants would benefit from wood ashes. This assumption is wrong. Some plants yearn for the nutrients found in wood ash. Other plants can be harmed by wood ashes. In this article I'm going to explore the plants that love wood ashes and the ones that can be damage by wood ashes.
Plants that like wood ashes
The following plants will benefit from wood ash in your soil. Be sure to test the soil for pH levels before adding wood ashes to make sure the resulting pH will be suitable for a specific type of plant.
Anchusa Azurea (Italian Bugloss) - grow well in acidic, alkaline, or neutral soil.
Arborvitae - like slightly acidic to slightly alkaline soil with a pH of 6.8 to 7.2.
Autumn Joy - like soil that is slightly acidic or slightly alkaline with a pH of 6.5 to 7.5.
Bearded Iris - like neutral to slightly alkaline soil with a pH of 6.8 to 7.0. Use a small amount of wood ash to in more acidic soil to make it favorable for the bearded iris.
Black-eyed Susans - like slightly acidic to slightly alkaline soil with a pH of 6.8 to 7.7.
Boston Ivy - like acidic to slightly alkaline soil with a pH of 5.1 to 7.5.
Candytuft - like soil that is slightly acidic or alkaline with a pH of 6.6 to 8.5.
Catmint - like soil that is acidic or alkaline with a pH of 6.1 to 7.8.
Centaurea montana - like acidic to slightly alkaline soil with a pH of 5.5 to 7.0.
Clematis - like alkaline soil with a pH of 7.0 to 8.5.
Wild Red Columbine - like slightly acidic to alkaline soil with a pH of 6.8 to >7.2.
Delphinium - like neutral to slightly alkaline soil.
Easter Lilies - like acidic to slightly alkaline soil with a pH of 6.5 to 7.0.
Elijah Blue Fescue - like acidic to alkaline soil with a pH of 5.5 to 7.5.
Foxglove - like acidic to alkaline soil with a pH of 4.5 to 8.3.
Goldenrod - like acidic to alkaline soil with a pH of 5.5 to 7.5.
Hens and chicks - like slightly acidic to slightly alkaline soil with a pH of 6.6 to 7.5.
Hosta - like slightly acidic to slightly alkaline soil with a pH of 6.5 to 7.5.
Jacob's Latter - like acidic to slightly alkaline soil with a pH of 6.2 to 7.0.
Lavender - like slightly acidic to slightly alkaline soil with a pH of 6.7 to 7.3.
Lenten Rose - like slightly acidic to alkaline soil with a pH of 6.5 to 8.0.
Maiden Grass - like acidic to slightly alkaline soil with a pH of 5.5 to 7.5.
Maltese Cross - like slightly acidic to slightly alkaline soil with a pH of 6.5 to 7.5.
Meadow Rue - like acidic to alkaline soil with a pH of 5.0 to 8.0.
Pasque flower - like alkaline soil with a pH of 7.0 to 8.0.
Reticulated Iris - like slightly acidic to slightly alkaline soil with a pH of 6.1 to 7.8.
Vinca Minor - like acidic to alkaline soil with a pH of 5.0 to 8.0.
Virginia Creeper - like acidic to slightly alkaline soil with a pH of 5.1 to 7.5.
Winter Jasmine - like acidic to slightly alkaline soil.
Woodland Phlox - like slightly acidic to slightly alkaline soil with a pH of 6.8 to 7.7.
Yarrow - like acidic to alkaline soil with a pH of 4.0 to 8.0.
Plants that don't like wood ashes
There are plants that don't do well in alkaline soil. These plants may not benefit from adding wood ashes to your soil.
- sweet corn
- cucumbers
- beans
- broccoli
- turnips
- squash
- onions
- cranberries
- blueberries
- huckleberries
- elderberry
- thimbleberries
- gooseberries
Mineral deficiency in soil
Plants need certain minerals to grow and flourish in your garden and yard. If your plants are deficient they will suffer. Symptoms that may occur are poor growth, yellowing and curling of leaves, and death of your plants.
Wood ash contains four important minerals that your plants need. The four minerals are potassium, calcium, magnesium, and phosphorous. Adding wood ash to your garden can help to add back or fortify these nutrients in your soil.
About 25% to 40% of wood ashes are made up of calcium compounds. 5% to 7% of wood ashes are potassium.
Wood ashes do not contain much nitrogen. You should other fertilizers to give nitrogen to your plants.
Acidic Soil
If your soil is acidic, you can use wood ashes to neutralize it. You can add a half pound to one pound per 100 square feet of soil once a year. Make sure not to let excessive amounts of water puddle after you apply the ashes to the soil. Excessive amounts of water will cause salts to build up and damage your plants.
Wood ash has been shown to work better than limestone in correcting overly acidic soil.
Alkaline Soil
If your soil is already alkaline, you will need to be careful of how much wood ash you add to it. Adding too much wood ash to soil that is already alkaline could cause the soil to become too alkaline. High alkaline soil can cause the same problems as mineral deficient soil; growth problems, plants dying, and leaves yellowing.
Best type of wood ashes for plants
Hardwoods are denser then softwoods. Because hardwoods are denser, they produce more ashes then softwoods. Hardwoods contain more potassium then softwoods.
Maple and oak are two of the best hardwoods you can burn to produce wood ashes for your plants.
Application of wood ash in soil
The best time to apply wood ash to your soil in in the fall. This gives the soil four months to allow the wood ash nutrients to be absorbed and become stable.
You can add anywhere from 5 to 15 pounds of wood ash per 1000 square feet.
Wood ashes can play an important role in your plants lives. If your soil is too acidic, you can use wood ashes to neutralize it or even make it alkaline. Be careful not to make your soil over alkaline. Softwoods and hardwoods both contain the nutrients that are good for your plants. Hardwoods contain more nutrients.
Next time you burn some wood in your fire place or fire pit, don't throw those ashes out. Instead, add the to your soil as a nutrient rich fertilizer.