Planning for Spring

The Tucson Gardener

Chaste tree bloom.
Chaste tree, Vitex agnus-castus, bloom.

Current Cultivations

Garden Clubs

Garden Books

In the Garden Calendar

Tucson's Wildlife

Santa Rita prickly pear.

Local Garden Links

Links for Special Needs

The Archive

The Tool Shed

Gambel's quail chick.

FAQ

Glossary

Search

Site Index

You're visiting Tucsongardener.com

Planning for Spring
With warmer temperatures and longer days just around the corner one has to give some thought to all the new growth trees and shrubs will produce come spring. Sure it's winter in January and February (if you can call our mild climate winter) and many desert gardeners are still enjoying the bedding plants put out in the fall knowing they'll grow even more profusely when the temperatures warm up both during the day and night.

All those trees and shrubs producing new growth could use a little extra food to give them strength and encouragement when they start growing. That's why you want to consider doing some feeding in February so the nutrients will be in the soil and available to the plants when they start expending all that energy putting out new leaves, flowering and sending out shoots. The food is nutrients found in fertilizer whether organic or the inorganic. It's found in bags, boxes, bottles or in the form of pellets or spikes or whatever else the fertilizer companies have come up with to sell their products to consumers. Rose food, tree and shrub food, tomato food, vegetable food, African violet food and plain old plant food are all names you'll spot on the shelf. Names that are nothing more than a sales tactic asking you to "reach for us and take us to the sales counter".

Are fertilizers really plant food?
The fertilizer manufacturers are really spreading it around when they sell to gardeners anxious to grow lush, beautiful plants inside and out. But are all these fertilizers really plant food? Here are a couple of terms that might jog your memories from those biology classes you took as part of your education. Remember chlorophyll? The green stuff found in leaves and stems. What about photosynthesis? Ring a bell? Plants use sunlight, water, and carbon dioxide to produce carbohydrates which in turn feed the plant. The elements found in fertilizer don't feed the plant but they do help make the plant's food production possible.

So you better know what you really need to purchase to make your plants grow better before you head off to buy your fertilizer. Mainly it's the N, P, and K - nitrogen, phosphorous and potassium the three primary nutrients that plants require along with oxygen, hydrogen and carbon which they get from the air and water. Other nutrients include calcium, magnesium and sulfur and then the trace elements of iron, manganese, copper, boron, zinc, chlorine and molybdenum. Sixteen crucial elements for good plant growth. All this stuff makes me wish I'd paid more attention in my chemistry and soil science classes when I had the opportunity. But not to worry. What desert gardeners are really interested in for Tucson's desert soils is nitrogen and phosphorous. Most of the other elements are all ready in the soil and we don't have to worry about them unless something goes astray and they get hooked up with some other element and become unavailable to the plant.

Nitrogen promotes the plants overall growth of leaves and stems. The phosphorous helps flowering, fruiting and root growth while the potassium helps flowering, fruiting and the plant's resistance to disease. If you've purchased fertilizers you've seen the bags of ammonium sulfate with the 21-0-0 percentage rating and the ammonium phosphate with the 16-20-0. The numbers indicate the percentage of nitrogen then phosphorus and finally potassium. There's plenty of potassium in our soil so that's why there's the big zero in the percentage rating on these two highly used chemical fertilizers.

Making fertilizer available to the plant
Most fertilizers, unless a quick acting foliar spray, are applied to the soil where it's mixed with water and then gets absorbed into the plant through the roots. Some fertilizers depending on their composition are readily available while others are slower in their usefulness to the plant.

The granular ammonium sulfate is water soluble so it can get washed into the soil and quickly become available to the plant. Maybe too quickly as it flushes down past the roots with each watering. Several small applications over a period of time would be more beneficial than one all at once application.

There are slower releasing fertilizers available so that the nutrients are supplied to the plants over a longer period of time. Good for the plant and a time saver for the gardener because one application will last a long time.

If you're adverse to the chemical applications you can add the slower releasing organic fertilizers like a well composted manure or even compost if you happen to have a good supply available. These will, while working with soil organisms, Betsy and her by product. slowly release a variety of nutrients in very small amounts but at the same time the organic matter can improve the structure of the soil improving its ability to hold moisture. Some of the other organic fertilizers include bone meal (phosphorus), blood meal (nitrogen), seaweed (trace elements) and fish emulsion (nitrogen).

All fertilizer packages come with instruction for their usage. Read the labels, follow instructions, or apply less than suggested. More is not better. Excess fertilizer can actually damage the roots of a plant. For the few plants that show a specific ailment like zinc or iron chlorosis you might want to take a sample to your garden center or to Ag. Extension for possible diagnosis and suggestions for the best cure.

Remembering where we live
Gardeners can be in a hurry to get their plants to grow and maybe we expect our plants to be perfect specimens with the ultimate shade of green leaves and an abundance of flowers or fruit every year. We might curse the first signs of chlorosis (a yellowing of the leaves) and head for the garden shed to find a chelate to spray on the leaves hoping to get back the solid, rich green leaves we want.

We forget we live in the desert where the soils are less than perfect and the native vegetation has adapted to soil, climate and low amounts of rainfall. The native plants do quite well without the regular application of fertilizer. If you're using large amounts of chemical fertilizers to maintain your garden maybe you need to take a lesson in evolution and learn to adapt to your environment instead of trying to change it. But then, like many a gardener, you might ask, "where's the challenge in that?" (1999)