Gardeners have lots of words and jargon we use but many times do not clarify what they mean. Today I will try to define some of those words.


Bt. This abbreviation (which always has the small t) stands for “Bacillus thuringensis”. This is a bacterium that kills caterpillars and the larvae of Mosquitoes, but does not harm fish, birds, or pets. It will also kill the larvae of Butterflies such as the Monarch so one must be careful to spray only the “bad guys. For plants it is available as a spray or a powder and will not hurt the eggs or adults. I recommend you add a few drops of soap to the spray to help it stick to the leaves of the plant. It is also available as a liquid, pellets, or donuts for use in a pond or birdbath to kill the larvae of mosquitoes.


SYSTEMIC pesticides go into the cells of plants and is distributed within the plant. A systemic insecticide is a product that enters the cells of plants to poison those pests who chew. It can be put on the top of the soil and watered in and then taken up by the roots system and distributed throughout the plant. These products should not be used on plants you are using for food as it will be present in the leaves and fruits.  I use a systemic insecticide on my houseplants when I bring them in from outside and then as required during the winter. A systemic insecticide can be used on flowering plants but some are concerned about its use outside because of the possible effect it has on pollinators. Imidacloprid is a soil drench type of systemic insecticide that is used for trees and shrubs. There are also systemic fungicides that help a plant fight off diseases.


PHEROMES used in traps are a subject of debate. They are hormones to attract certain pests into a trap of some sort.  All of the authors agree they “attract”, but some say they bring in bugs from afar to increase the number in your yard.  Quite often the traps are used to get counts of how many insects are in the area.


PERLITE are small, light, white pieces of volcanic rock full of holes caused by the heat.  It lightens the potting soil and improves its ability to hold air and water.


VERMICULITE is a light material made from mineral deposits and is used as a soil additive to lighten the soil and help it hold air and water. I like to keep my bulbs over winter in containers of vermiculite. I also like to check during the winter and perhaps spray some moisture to keep everything from drying out. Most good potting mixes and seed starting mixes contain vermiculite and perlite.


BRACT is a specialized leaf that frames a plants true flower.  They may be leaf like or can be very colorful.  They usually live longer than the blossoms.  A good example is the Poinsettias red bracts. The true flowers are the little yellow “bumps”.  Some of the “flowers” on Bromeliads are really bracts.


CALLUS is an isolated thickening of tissue. Directions when dealing with propagating cactus often say “remove the young plant and let it be in dry air long enough to form a callus. As the cut plant part dries, it forms a hard surface thus preventing the loss of sap and sealing out water, fungi, and bacteria.  Roots will form from that surface and not be as liable to rot.


RHIZOME is a swollen stem part that lies horizontally just beneath the soil surface.  Many of our plants reproduce this way.  There are short and thick ones and long slender ones. Thick ones are full of stored food by fall and can be divided into pieces to produce new plants in the late fall or spring. Some of these are Asters, Phlox, Gallardia, Mums, Daisies, and Rhubarb. The slender ones have nodes that produce new plants at that point.  An example are some of the grasses.


LAYERING is a method of propagation. It can be done with houseplants or with shrubs.  If you want a shrub from your grandmother and you have a little time, there are many plants that will form roots along their stem.  Find a lower stem and place it on the ground to make sure it reaches. Then scratch the side that will be against the soil to stimulate root growth.  Then I like to place a rock or brick above that area to be sure it touches the ground all of the time.  Some shrubs root faster than others, but you can check by a slight tug to see if the new roots are there and fastened in. There is an advantage of this over propagating by cuttings. Also, this is easier than taking cuttings as the new plant is always being “fed” while it develops its roots.


VEGETATIVE REPRODUCTION is the use of stems, leaves, or roots to produce new plants.  One reason for this is to produce a plant exactly like the parent. Seeds may have been pollinated by a quite different plant and could vary in size, shape, color, and other characteristics. In this way valuable varieties are preserved making a standardized product. You may have noticed after getting a new variety that it may have a sign attached saying “propagation is prohibited”. Examples of this are fruit crops, nuts, and many of the newest flowering and ornamental crops.

Copyright 2009