Plant growth requires energy. When plants are fighting damage from pests or pathogens, that energy often redirects to tasks more important for the plant's survival, and growth languishes. Stunted growth is often one of the first signs that there's something wrong with a plant, and lagging growth is a common symptom of plant disease and pest problems.
At the tips of shoots and roots, plants have specialized tissue called apical meristem, from which the majority of growth arises. Cells in these regions divide rapidly through a process called mitosis. Because mitosis requires energy, if the plant isn't receiving adequate energy because of a disease or pest problem, or if the energy is needed for survival, growth won't occur as rapidly.
A range of problems cause stunted growth in plants. Diseases like root rot and pests like whiteflies may reduce growth because they deplete the plant of nutrients. Cultural and environmental problems may also cause plants to grow poorly. For example, poor soil nutrition, improper pH and competition from weeds all affect growth. Planting during harsh conditions, such as cold weather, also stunts growth in some species.
When faced with a plant not growing as you expect it should, the challenge becomes identifying the cause of the problem. In some cases, you can see the insect or fungus affecting the plant, or you may realize that you planted a vegetable too early, and it was affected by frost. Distinguish between living and nonliving causes, advises the Ohio State University Extension. Make sure you've accurately identified the plant and know its normal growth habits. Carefully observe what is wrong with the plant, noting as well its environment and the condition of other plants around it, especially of the same species. Research to find common problems for your plant and match your observations against them to achieve a possible diagnosis.
Where to Go for Help
If identification of the problem continues to elude you, contact your local extension office or nursery. Experts there may be equipped to help you identify and treat common plant problems that might cause stunted growth, or they can help you collect and submit samples to a diagnostic laboratory.
One of the key ways to ensure proper growth for your plant is to maintain optimal growing conditions. Know your plant and its preferences and provide adequate water, light and nutrition. Not only will this prevent stunted growth from environmental stressors, it will also reduce susceptibility to diseases and pests that can threaten the health and growth of your plant.