Issue: Decem1er 8, 2001

Science fair project


My daughter is doing a Science Fair project on plants. She is trying to find out which helps plants grow better - coffee, tea, or Pepsi. She is looking for documentation about this. Do you know where we could find some information? -Deb Q.


Specific information on the effects of coffee, tea, and soft drinks on plants may be difficult to find. To find information on necessities for plant growth, you should be able to find books on plant physiology in a local library. A plant physiology book will probably not discuss these drinks in relation to their effects on plants, but the books will discuss water, osmosis, the uptake of material by plants. The coffee and tea molecules are probably not able to enter the plant because they are so large. The water will be the most useful aspect of these liquids. Over time, the large molecules will be decomposed by bacteria and fungi in the potting soil and their constituent compounds (mineral components) will be released into the soil where they become available to the plants.

Studies such as your daughter's are common at Science Fairs. There are confounding factors that must be considered when doing this study. One of the most common problems encountered by the students is to fail to consider the effects of sugar. There is a lot of sugar in the soft drink and none in the others unless the student adds sugar. This sugar will enhance growth of fungi and bacteria in the potting soil. This may have unexpected results on the plants.

To learn more about the effects of these pathogenic organisms on plants, look for books on plant pathology. This will become an interesting part of the study. Perhaps a solution of water and sugar would be a useful addition to the experiment. My hypothesis that the solutions with a high concentration of sugar will do more harm than good. Good luck to your daughter as she conducts her experiment.

Xeriscaping in winter


Can I plant a xeriscape in the winter?


Planting is possible if the soil is not frozen, but some of the plants may have a difficult time surviving until their roots begin growing. For some xeriscape plants, much root growth occurs in the summer (monsoon season) when water is naturally available. Other plants will transplant easily and develop roots in the spring.

Winter is a great time for planning. It is also a good time for installing non-living elements of the landscape if the ground isn't frozen and you can work outside. Installation of an irrigation system can be done in the winter, but there is a hazard in testing the system for leaks if you don't drain it well and nighttime freezing is likely. It is unwise to install the system and cover it with soil without testing for leaks. If you can drain it after testing, this is not a concern. Walls may be built, soil may be graded, and much of the physical work done in the winter as long as the soil is workable.

As stated above, plants may be installed, but that depends on the type of plant. Even plants which can be planted now will probably establish better if you wait a little while to plant them. So, yes you can install at least portions of a xeriscape in the winter if you watch the weather forecasts carefully.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

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