Question: We saw a beautiful plant in a local garden store over the weekend called Norfolk Island pine. The clerk said they are popular as a live indoor Christmas tree. If we purchase one, will we be able to grow it outside successfully after the holiday season?
Answer: The Norfolk Island pine continues to grow in popularity as a live indoor Christmas tree. Its beautiful, lush green twigs of soft needles are easy to decorate with festive holiday ornaments. Unfortunately, the Norfolk Island pine is too tender to plant outdoors in our climate. The good news however, is that it makes a great houseplant when given proper care.
The ideal climate for this species is cool and bright, responding well to daytime temperatures ranging from 60-70 degrees F. and slightly cooler at night. Although the Norfolk Island pine will adapt to bright indirect light, the plant will look best with a couple of hours of direct sunlight daily. If the light source is coming from just one direction, you'll want to rotate the plant a quarter turn weekly to keep it from tilting to one side.
What is most challenging for home gardeners is providing the plant with the high relative humidity it requires. Norfolk Island pines thrive at 50 percent relative humidity. It's not unusual for the average house to drop to 15 percent during the winter heating season, unless steps are taken to increase moisture in the air.
Question: We burn a lot of wood and consequently have lots of ashes. Is there such a thing as adding too many ashes to the garden? Are there plants that should not have ashes placed around them? Do they have any real fertilizer value?
Answer: Wood ash does have fertilizer value, the amount varying somewhat with the species of wood being used. Generally wood ash contains less than 10 percent potash, 1 percent phosphate and trace amounts of micro-nutrients such as iron, manganese, boron, copper and zinc. Trace amounts of heavy metals such as lead, cadmium, nickel and chromium also may be present. Wood ash does not contain nitrogen.
The largest component of wood ash (about 25 percent) is calcium carbonate, a common liming material that increases soil alkalinity. Wood ash has a very fine particle size, so it reacts rapidly and completely in the soil. Although small amounts of nutrients are applied with wood ash, the main effect is that of a liming agent.
Increasing the alkalinity of the soil does affect plant nutrition. Nutrients are most readily available to plants when the soil is slightly acidic. As soil alkalinity increases and the pH rises above 7.0, nutrients such as phosphorus, iron, boron, manganese, copper, zinc and potassium become chemically tied to the soil and less available for plant use.
Applying small amounts of wood ash to most soils will not adversely affect your garden crops, and the ash does help replenish some nutrients. Because wood ash increases soil pH, adding large amounts can do more harm than good. Keep in mind that wood ash that has been exposed to the weather, particularly rainfall, has lost a lot of its potency, including nutrients.
Specific recommendations for the use of wood ash in the garden are difficult to make because soil composition and reaction varies from garden to garden. Acidic soils (pH less than 5.5) will likely be improved by wood ash addition. Soils that are slightly acidic (pH 6.0 to 6.5) which includes most of our local gardens, should not be harmed by the application of 20 pounds per 100 square feet annually, if the ash is worked into the soil about 6 inches or so. However, if your soil is neutral or alkaline (pH 7.0 or greater), find another way to dispose of wood ashes.
Wood ash should never be used on acid loving plants, such as potatoes, rhododendrons and blueberries.
Question: We are beginning to observe black areas on the soil surface in an area where our lawn is doing poorly. Can you tell us what's causing this?
Answer: When moss first colonizes an area, it produces a black, slimy mat across the area before the green vegetative structures form. The green structures are composed of branchlike filaments called protonema and are easily confused with algae. These then bud out and give rise to more familiar green structures that are easily recognized as moss. Winter conditions of low light intensity, cool temperatures and high rainfall are ideal for moss development in our coastal climate.
Commercial moss killers registered for use on turfgrass provide only temporary relief until during our winter months.
EDITOR'S NOTE: For answers to local gardening questions, contact Master Gardener Rachel Gana at 642-8723 or e-mail her at: firstname.lastname@example.org.