Introduction to Vegetable Plants (continued)…
Annual Plants
A tomato plant, which is an annual, will germinate from seed, grow to adulthood, produce its fruit (the tomato) and then wilt and die all in a single growing season. The plant produces a flower which transforms into a red tomato fruit that contains the seeds for reproduction. The same being true with a cucumber, melon or pepper plant. In these vegetables, the seeds are in the fruit that we eat, and these seeds are produced in the late stages of the growing season (late summer or early fall).
Other annuals, such as lettuce and spinach, produce tender, edible leaves when mature, and then quickly create a seed stalk at the end of their lives (late summer or fall) which contains the flowers and seeds for reproduction. For instance, when spinach determines that the days are growing shorter (or when it becomes too hot), it will bolt and begin to produce the seed stalk, flowers and seeds for next years generation. The plant quickly becomes tough and inedible and is said to have ‘gone to seed’. This happens in late summer or early fall, all within the same growing season that the seed originally germinated. Annuals germinate, mature, reproduce and die all in one year, or one growing season.
Biennial Plants
Most gardeners think that a carrot is an annual plant, because it produces the carrot (called a taproot) in the first year, and dies when we pull the carrot from the ground and eat it. However, the carrot grows the taproot not in order to provide food for us, but in order to store energy to power the second year of its life cycle, when it will use it to produce flowers and seeds in order to reproduce itself.
The first year is known as vegetative growth, where the carrot puts all of its energy into producing the storehouse of food (the carrot taproot) that it will need in the second year of its life. And in the second year it goes to seed, meaning that it stops forming the taproot and begins to draw the energy from it to develop the flowers and seeds it needs for reproduction. When this happens the carrot taproot, which is now being drained of its nutrients, becomes tough and woody, becoming inedible to humans. But since humans are smarter than carrots, we harvest the carrot in the first year of its life cycle when the taproot is tasty and edible for us and we do not allow the carrot to go to seed. Biennials live for two years. The first year they produce their vegetable parts that we eat and the second they produce seeds for reproduction.
Perennial Plants
A rhubarb is an perennial vegetable, and will over winter in most climates, producing the rhubarb stalk that we eat in Spring. The leaves of the rhubarb die off in fall and the roots become dormant, waiting until the arrival of Spring weather. Much the same with the asparagus plant, producing its shoots in the Spring and becoming dormant in fall.
It is important for the vegetable gardener to know the life cycle of a vegetable because it determines when you want to harvest the leaves, bulbs, stems, roots or fruit of the plant. If you wait too long, and the plant goes to seed (it begins its reproduction cycle), the vegetable quickly becomes inedible. It is not necessary to become a botanist in order to grow good vegetables, but a basic understanding of plant life cycles will only make you a better, more knowledgeable gardener.
Growth Cycle
Vegetable plants begin their lives as seeds, which consists of an embryonic plant, a stored food supply and a protective coat. A seed is one of the most amazing objects in nature being able to lay dormant for many years and still remain viable. When conditions are right, the seed case splits, the roots begin to form and the stem and leaves break ground and head for sunlight. When the green leaves are formed, photosynthesis begins, a complex process by which sunlight is turned into carbohydrates in the presence of carbon dioxide. For photosynthesis to occur, the plants need soil nutrients as well, including such things as iron, chlorine, sulfur, zinc, copper, manganese and calcium. So plants cannot photosynthesize light in a vacuum: they must have mineral nutrients, and a supportive soil structure as well.
In order for a vegetable plant to grow it must ingest nutrients through its roots, which anchor the plant to the ground, and transport these nutrients, along with water, to the stem, leaves, flowers, seeds and fruits of the plant, a process known as transpiration. It does this by evaporating water through its leaves, thereby creating a hydraulic effect that sucks-up water and nutrients from the roots into the leaves, seeds, flowers and fruit.
For a vegetable plant to utilize soil nutrients, the nutrients must be in a soluble form, and must also be in contact with the roots and root hairs as well. If these nutrients (fertilizers) are below the root level (leached out), they might as well be on Mars as far as the plant is concerned for they cannot be utilized. In the 1800’s, a German chemist named Justus von Liebig discovered that plants need mainly nitrogen, phosphorus and potassium, as well as numerous trace elements. If these nutrients are not present in the proper proportions, your vegetables will have a difficult time producing their bounty, so it pays to have a basic understanding of nutrient requirements.
 |
 |
 |
 |
 |
| Tuber |
Leaves |
Sprouts |
Bulbs |
Fruits |
As the vegetable plant reaches maturity it begins to form the part of it that we eat, be it the tuber (potato), leaves (cabbage), sprouts (Brussels sprouts), bulb (onion) or vegetable fruit (tomato/squash/pepper). It is at this stage that we must harvest the vegetable and either freeze or can it for future use, or eat it fresh when ripe. Depending upon how much of the plant is harvested, the plant can continue producing more food, as in the case of a tomato or pepper plant, or ends its life, as in the case of a carrot or radish. However, when environmental conditions dictate, the plant will cease all production of food and either die or begin its reproduction cycle, such as bolting.
Pests and Diseases
Vegetables taste good to not only humans but to other members of the animal kingdom, such as deer and raccoons, to the insect kingdom, such as moths, beetles, flies and gnats, and to the fungi kingdom, such as molds and mildew. So the gardener has a fight on his or her hands to keep these pests and diseases at bay, and try to save the harvest for ourselves, something not always that easy.
Organic gardeners try to fight the pests with products and procedures as closely aligned with nature as possible and with as little disruption to the natural world as is feasible. But many commercial farmers have trouble doing this however, and rely upon man-made chemicals to fight the bugs. We are all aware of these differences, the harm to the environment and beneficial life-forms when powerful artificial chemicals are indiscriminately used, and the effect on our health, as pesticides are basically poisons which tend to be ingested by the vegetables. If it is at all feasible, home gardeners should try to be as organic as possible, trying to live within the confines of the natural world and only deviating when absolutely necessary. Fighting pests and diseases using organic methods is more difficult and labor intensive, but the food is safer and might even taste better. Grocery stores sell the commercially grown food that utilize strong pesticides and fungicides to battle insects and fungi. Leave them sell this food, but YOU grow your vegetables using more natural, organic methods and reap the bounty of better tasting, safer vegetables.
Summary
Vegetable plants tend not to grow well by themselves. A loving hand from the gardener, a basic knowledge of plant life cycles, nutrient and water requirements, disease and pest control and harvesting techniques all contributes to a successful vegetable garden.
