A Plant's Circle of Life
A basic knowledge of the different stages of growth and development plants go through can help growers know what to expect from their gardens, and when.
One of the benefits of indoor gardening is that it allows the gardener control over the seasons, and the environment plants are grown in. With this added element of control, the natural life cycle of plants can be somewhat manipulated to the advantage of the savvy indoor gardener. But before the novice gardener can begin manipulating conditions in the indoor garden to affect a plant’s stages of growth, a grower must have a good understanding of how plants start, develop and grow.
The Seedling and Growth Stages of Plants
A plant starts off as a seed. Seeds are tiny, live plants in stasis, usually with a food store inside a protective shell called a seed coat. The tiny plants already have one or two seed leaves (cotyledons), a stem (hypocotyl) and a root (radicle). Under the right environmental conditions, viable seeds will sprout. Seeds always require water, generally require warmth, and sometimes have specific light requirements.
To conserve space and help keep the sprouting seeds manageable, rooting cubes, cell partitions for 1020 trays or plastic cups are just a few of the options to house young seedlings. Growers should note the planting date, as well as the varieties planted. Plastic label stakes can be moved from container to container with the plant. A warm location is usually preferred, and sometimes a heating mat is used to help maintain sprouting temperature.
Moisture passes through the seed coat through tiny holes called micropyles. Although not usually necessary, presoaking the seeds in water may hasten this process. The moisture swells the embryo, which employs hydraulic pressure to burst the seed coat. The radicle extends to establish the root system, and the cotyledons unfurl and become the first leaves of the plant. Seedlings are tender and susceptible to mortal damage, so should be treated carefully.
Vigorous growth occurs during preadolescence. The plant develops in size, both in leaf and shoot development, and extends the root system. As seedlings outgrow their original containers, they should be carefully transplanted into larger containers.
Cuttings are sometimes taken from a plant and rooted in a process known as vegetative propagation. With this method, a growth tip and a section of stem are cut from the parent plant and the stem is kept moist and placed in a lighted, warm location until roots develop. This is possible because there are cells called meristematic cells in the stem that under the right conditions will become root cells.
Plants started from cuttings are sections of the mother plant from which the cuttings came, and as such tend to be very similar to each other. These types of plants are commonly referred to as clones, as they share the same DNA as the mother plant. Gardeners use this to their advantage to increase numbers of superior specimens, or to learn about a particular plant by examining its cuttings.
For example, if a plant cutting is taken and rooted, then exposed to flowering conditions, then the flower color of the parent plant can be determined even though the original parent plant hasn’t started to flower. Making sure each cutting has an appropriate label can simplify identification when matching plant cutting to parent.
The Flowering Stage of Plants
Once flowering conditions are met, which depend on the type of plant, a plant will enter adolescence and begin to produce flower buds. As energy from the plant is diverted from growing larger in favor of flower development, overall growth slows. The exact trigger for flowering is dependent on the type of plant grown, but maturity or hours of darkness are two of the most common triggers for flowering.
Plants that are photodependant for flowering use photoreceptors known as phytochormes to track the length of the dark periods. Some photodependant flowering plants are “short day” plants, which flower in the long nights of fall (winter and spring), and some are “long day” plants, which flower in the middle of summer.
An indoor gardener can use this knowledge to their advantage. For example, when growing a short day plant, the dark periods can be kept short (or eliminated altogether) to keep the plant in an immature phase to encourage vigorous growth, and then when desired, growers can initiate flowering by extending the dark periods to simulate the longer nights of fall (11-12 hours).
As the flowers reach maturity, they open and become available for reproduction. If pollen from a male flower organ (stamen) reaches a receptive female flower organ (pistil), then seed development can occur. In some plants, the flowers are known as perfect flowers, or complete flowers, and both the stamen and the pistil are in the same flower, allowing it to self-pollinate. In other plants, the male and female flowers are separate but appear on the same plant, also allowing for self-pollination as long as the pollen is transferred to the female flower.
A third group of plants (dioecious plants) have individuals that either produce only male flowers or only female flowers. One way to prevent dioecious plants from producing seeds is to remove any male plants (and their pollen) so the female flowers do not become fertilized. Some decorative flowers are grown this way for aesthetic reasons, as it encourages further flower development.
The Fruiting Stage
In fruiting plants, the female flowers develop fruit with the fertilized seeds. The fruits are then harvested when ripe. After the fruits and seeds are fully developed, they will eventually separate from the plant. In a natural setting, the seeds then have a chance to start again as the next generation of plants. For most perennial plants (plants that live for more than two years), the parent plant will have the opportunity to repeat the growth and flowering stages again, but in annuals (plants that complete their life cycle within a year), the plants must be started again from seeds or cuttings for the next year’s gardening season.
Regardless of when the plant is harvested, take the planting date with the harvest date, and calculate the number of days the plant took to grow to harvest. Then divide the amount of harvest by the number of days to find the rate the garden (or a particular plant) produced. For example, if a black krim tomato plant produced 5 lb. of fruit and took 110 days from seed to harvest, the daily production rate would be .045 lb. per day.
Plants with smaller harvests such as saffron or lavender may be easier to measure in smaller units such as ounces. This critical bit of information can be useful when comparing seasons and varieties.
Understanding the basic life cycles of plants can be helpful in knowing what to expect from your garden, and in what order.