| How Plants Grow
Seeds, roots, stems, leaves, flowers, fruits -- if you understand how these basic plant parts function, both individually and together, you'll find all aspects of gardening and plant care more comprehensible, manageable, and enjoyable.
|
| Why Leaves are important
Although leaves vary in appearance and structure (a few examples are shown at right), all have as their basic function the manufacture of sugars and other carbohydrates through the complex process of photosynthesis : the interaction of light energy with chlorophyll (the green material in leaves), which converts carbon dioxide from the air and water from the soil into sugars and oxygen.
Photosynthesis requires large amounts of water. Once this water is drawn up from the roots through the stems and into the leaves, it encounters carbon dioxide, which has entered the leaf through the stomata, minute pores located primarily on the leaf undersides. Besides allowing the inflow of carbon dioxide from the air, the stomata permit the outflow of oxygen, which is a byproduct of photosynthesis, and of excess water vapor (transpiration). Since a leaf's interior tissues must be moist but outside air is often dry, the stomata can close as needed to prevent dehydration. Leaves can be further protected from drying by an outer coat (epidermis) that may be hairy, extra thick, or waxy.
Photosynthesis comes to a halt in deciduous plants during their leafless dormant season, and it slows greatly in evergreen plants during their modified dormancy in cold weather. For this reason, most plants require much less water from late fall to early spring, so gardeners can dig and move them with less damage during this time.
Anything that interferes with photosynthesis and the subsequent transfer of sugars throughout the plant can have harmful consequences. For example, if leaves are cut by pruning or chewed by insects, the injured tissue may seal to prevent the loss of moisture--but the leaves will not regrow, and the area available for nutrient manufacture will be decreased. Soot, grime, and dust on leaves can interfere with free air circulation through the stomata and reduce the amount of sunlight available to the leaves. A smothering mat of leaves on a lawn can halt the production of chlorophyll in the grass, causing it to turn yellow and stop growing.
|
| Managing Soil
Plants won't grow well aboveground if their roots don't have favorable conditions below ground. Learning a few basic facts about your soil will let you know what improvements may be needed before you plant -- and you'll have a better idea of the right way to water and fertilize your garden, too.
|
| Fertilizers
Fertilizer sections at nurseries, garden centers, and supply stores dazzle the gardener. The shelves are piled with boxes and bottles, the floors covered with bags stacked high. Labels identify the package contents as "rose food" or "vegetable food," "lawn fertilizer" or "general-purpose fertilizer." In some stores, you'll find bins filled with bone meal, blood meal, or hoof-and-horn meal--all labeled "natural fertilizer." Choosing the right products to keep your plants healthy can often be a bit confusing.
Understanding N-P-K
Regardless of its type, any fertilizer you buy will come with information about the nutrients it contains. Prominently featured will be the N-P-K ratio, the percentage the product contains by volume of nitrogen (chemical symbol N), phosphorus (P), and potassium (K). A 16-16-16 fertilizer, for example, contains 16% nitrogen, 16% phosphorus, and 16% potassium. A 25-4-2 formulation contains 25% nitrogen, 4% phosphorus, and 2% potassium. All fertilizers contain at least one of these components; if any is missing, the ratio will show a zero for that nutrient (a 12-0-0 fertilizer contains nitrogen but no phosphorus or potassium, for instance). Boxed, bagged, and bottled products display the N-P-K ratio on the label. For fertilizers sold in bulk from self-serve bins, the ratio is noted on the bin; for future reference, be sure to write the information on the bags you fill and bring home.
|
| Water
How much water do my plants need? How often should I water, and what's the best way to do it? How can I conserve water? These and other important—and often perplexing—questions are addressed in the following sections.
Methods for applying water range from simple hand-held sprayers to hose-end sprinklers to more complex drip systems and underground rigid-pipe systems. The method or methods appropriate for you depend on how often you need to water the size of your garden, and how much equipment you want to buy.
|
|
