- Callus
- The new tissue that grows over a plant wound or cut.
- Canker
- An erosive eruption on a stem or truck, usually exuding a viscous liquid or the spore of the fungus that causes it.
- Chelicerae
- Spiders have mouthparts known as "chelicerae" on which their fangs are located.
- Chlorophyll
- A group of green pigments within the plants cells which effect the conversion of solar to chemical energy by the process of photosynthesis.
- Chlorosis
- A yellowing of the leaves of a plant due to a lack of chlorophyll.
- Clay Soil
- Heavy, poorly drained soil.
- Climber
- A plant that climbs on its own, using twining, gripping pads, tendrils or some other method to attach itself to structures or other plants. Plants that need to be trained to a support are properly called trailing plants, not climbers.
- Cold Frame
- A low structure with a translucent top, used for protecting plants from the weather and for hardening-off young seedlings.
- Complete Fertilizer
- A plant food containing nitrogen, phosphorus, and potassium.
- Compost
- Decomposed organic matter used to improve soil.
- Conifer
- A cone-bearing plant; usually evergreen but the larch is deciduous.
- Corm
- An underground bulb-like stem capable of producing roots, leaves, and flowers.
- Creeper
- Prostrate or trailing plant that covers the ground or other plants.
- Cross pollination
- The transfer of pollen from one plant to another.
- Crown
- The part of a herbaceous plant at soil level, where the stems meet roots and new shoots develop. The highest part of a tree.
- Cultivar
- A horticulturally derived variety of a plant.
- Cultivate
- Work the soil in order to break it up; remove weeds;
- Cutting
- A piece of stem, root, or leaf capable of being grown to form a new plant.
- Cutworm
- The larvae of several species of moths that pupate just beneath the surface of the soil. While in the larval stage they emerge at night and "cut down" seedlings, then devour them, leaving no evidence beyond the severed stem. Control is by putting one inch tall collars around the stem of newly set transplants so that the cutworms can't get to them.
