How Plants Grow |Plant Factories
The Science of Plant Growth
Everyone has to start somewhere, so instead of thinking about what to do first or how to plan your garden, start with a. You may be surprised by what you find. Old shopping trolleys and bikes spring to mind here – as our introduction to our current garden – but that’s not always the case. Someone once told me to do nothing but tidy for the first year, until you see what’s planted already, but I’ve always been too impatient for that. I do think the idea of living in a house for three months before deciding on major decoration or renovation projects is a good idea to transfer to the garden. Although, if you move during the winter, this period might need to be longer, so that, with the coming of spring and summer, you give dormant plants and bulbs the chance to show what they can do for you. If you’ve acquired a brand new plot on a building site, you have my sympathies, but don’t despair. At least you have a blank canvas to work on, although you’ll need to spend a bit more time digging up building rubble and clay first.
Don’t be too enthusiastic, though. I recall my brother as a teenager, digging furiously to impress someone or other, while helping my parents dig a pond in their newish garden. Beneath the buried rubble he hit the main sewer and caused a major stink!
Clearing up rubbish, cutting the grass and clipping edges and hedges can make a world of difference. Get out the worst of the weeds. The area will look better straight away. Then you can see what’s worth keeping and decide on any new features and plants of your own. It’s easier and much more fun to let the garden ‘grow up’ around you gradually. Rushing into major changes can result in wasted time, effort and money.
Plants are like factories; from the outside they look relatively inactive, but there’s a lot going on inside. During daylight hours the green pigment in plants called chlorophyll traps sunlight and uses it as a source of energy to turn carbon dioxide from the air and water from the soil into carbohydrates. These are stored as starch in the roots and leaves. This process is called photosynthesis. At the same time, oxygen is produced as a waste product and is diffused into the air from the leaves. Plants respire rather like animals, taking in oxygen and giving off carbon dioxide. During the day more carbon dioxide is taken in during photosynthesis than is given out during respiration. During the night, when photosynthesis ceases, respiration is the only process going on.
Using the basic raw ingredients of minerals, air and water, plants manufacture hormones that control the ways different parts of the plant turn tissue into roots, buds and leaves. Forty or so different minerals are taken up in the water absorbed through the roots. Plants also make their own colouring materials, fragrances and a wide range of other sophisticated chemicals, including those which repel certain predators. Plants make their own structure, laying down lignin (wood) to support tall constructions such as trees and woody shrubs, stems of perennial plants, cabbage stalks, etc. Cellulose makes cell walls to build new leaves and other structures.
Water constantly evaporates from tiny pores in the leaves. This is called transpiration. If a plant loses more water than it takes up from the soil, it starts to wilt. The ultimate aim of any plant is to reproduce itself by shedding ripe seeds. To produce a wide range of offspring, many plants bear attractive flowers with pollen or nectar to attract insects that cross-pollinate them, creating new genetic combinations.
When ripe, these seeds are scattered by some ingenious methods. Seed dispersal takes different forms, for example wind, explosion or enlisting the help of animals and birds. Trees like sycamore and acer varieties have winged seedpods toaway on the breeze. Others like a good explosion, like the pea family. Tasty fruit ensures that animals or birds swallow the seeds of various plants and deposit them further way, along with their own supply of manure. Tomato seeds are about the most indestructible and can be found in sewage plants quite frequently. Other seeds, like burdock, have small hooks forming burs which attach themselves to passing legs or sides for transportation. Self-sown seedlings can be a real help with the budget when starting out, or when you want to increase your stock of plants. Just don’t be surprised if the seedlings don’t look exactly like the older, parent plants.