Time to check up on plant health.
COLUMN: ROOTS OF WISDOM
Everything that grows needs to eat. Plants are no exception. Our focus is currently on houseplants and any seedling flower and vegetable plants that we may have started.
However, the growth processes of indoor plants are similar to the trees, shrubs, perennials and groundcovers that reside in your yard. While the landscape remains locked in the frigid grasp of winter, why should we care about the nutritional needs of outdoor plants? Indeed our primary concern, at this time, is the indoor plants, but we can and should learn from them the signs of plant health so that our knowledge can be applied to all plants.
Why do we concern ourselves with plant health? Plants in poor health under-perform. They develop slowly. They flower less. They are more susceptible to disease and insect attack.
Indeed, one of the major reasons we should focus on growing healthy plants is to relieve ourselves of the need to use pesticides. Current research indicates that all organisms - plants, animals and people - are less likely to suffer from pathogens if they maintain a balanced state of health. Aristotle said it so well so long ago: "moderation in all things."
What are some of the signs of unhealthy growth? Small, undersized leaves, discolored leaves that display more yellow than green foliage, leaves that have brown margins and increasing populations of insects are all indicators of unhappy plants. While it is not possible to directly diagnose malnutrition from the appearance of a single leaf, it can serve as a clue or even indicator.
Light green leaves at the uppermost region of the plant or leaves in which the leaf veins are green and between the veins are yellow (interveinal yellowing) may indicate an insufficient supply of available nitrogen. A bronzy cast to the foliage from the top to the base of the plant usually results from exposure to low temperatures and a lack of phosphate.
Browning, especially patching of browning extending in from the leaf margins, often indicates that potassium is lacking. Note that a uniform browning of leaf edges and tips overall usually speaks of dry soil or hot drafts.
Indoors or outside, broadleaf evergreens such as gardenias, azaleas and rhododendrons that display interveinal yellowing are showing a need for iron. A material like iron chelate applied twice about 10 days apart will usually cure the deficiency. All other plants will be satisfied by an application of a complete fertilizer in liquid form.
Some knowledgeable houseplant enthusiasts follow directions and apply a slow-release fertilizer such as Osmocote.
A primary reason to look to the possible nutritional needs of your houseplants now is because the sun is stronger and the daylength longer. It is not because daylight saving began at 2 this morning, as that just changed the clocks not the number of hours of daylight, but rather because the daylength today is over 11 and a half hours long. By the end of the month, an additional hour of light will be added.
More light, both duration and quality, stimulates more plant development. For a plant to take full advantage of the increased light energy, more food and water will be needed. Thus, the month of March provides us with an opportunity to maximize houseplant development while we learn more about hunger signs of all plants.