Garden vegetables get a very tiny amount of their food from the air. However, for the most part, their food comes from the garden soil. Without a good supply of quality food, your plants will go hungry and will perish, irrespective of how much love and attention you otherwise lavish on them. There is an old adage that the soil must be rich or the garden will be poor. Bear this in mind when you are thinking about your vegetable garden.
Even with an abundant supply of food, plants may not flourish. This is because certain foods are possible for plants to use and others are not. By way of analogy, you or I could happily dine on steak and potatoes but would be less able to eat frozen chicken and vegetables. While the steak is in a form we can eat, the chicken is not. It's the same idea for the plants in your vegetable garden. To be of use to your crops, plant food has to be soluble so that the feeding roots can take it in. The solution also has to be quite weak - there's little to be gained by loading the soil with undiluted plant food. To grow well, your vegetables will need a weak water to plant food ratio.
Your vegetable garden will have to get its food from the soil. There are two ways this can happen: either the food is in the soil already, or you will have to put it there. The process of adding food to your soil is called manuring. In general, most soil will not be sufficiently abundant with plant food to make your vegetables grow well. Consequently, you will have to add lots of plant food to your soil to get good results.
Possible manures and fertilisers â€¨Broadly speaking, manure is organic, for example horse manure or decayed vegetable matter. Fertilisers are inorganic and include potash salts and other commercial mixed fertilisers. Despite the fact that chemical fertilisers can contain many times as much available plant food as manure, manure may be preferred because chemical fertilisers can sometimes have a nasty effect on the physical condition of the soil and are altogether more difficult to handle. You should be wary of using chemical fertilisers where children may play or pets may rummage. Lastly, if you prefer your food organic (as many people do nowadays) you will want to steer clear of chemicals where at all possible.
In any case, the best thing to put on your vegetable garden to grow big crops is good old fashioned barnyard manure (preferably well rotted and matured!). The plant food in fresh manure doesn't become available to your plants until it has decayed and broken up. You should therefore make sure that you don't put fresh manure on your vegetable garden as the plants will not see the benefit from it until the manure has decayed (which could take a while, particularly in heavy or clayey soils). Be careful too that the manure has not been left out in the sun and become burned and dry. When buying manure, it's worth keeping in mind what the animals themselves have been fed on. A well nourished horse, for example, will produce much better manure than poorly wintered cattle.
In addition to animal manure, you can generate good plant food from a compost heap. Fallen leaves, cut grass, vegetable waste from the kitchen, weeds and other matter that will rot should all go on your compost heap. You should make sure that your compost heap is well covered and kept in a compact heap. You should also make sure it is well moistened to aid decomposition. Occassionally, you should fork the compost heap over and restack it.
Another possible source of organic manure is the plowing of growing crops into the soil to enrich the land. In September, try sowing winter rye on all your cleared ground (once its been freshly raked). Plowing these crops back into the earth will enrich the soil and could save you money on other forms of plant food.
Applying manure â€¨It's also important to apply the manure properly. If possible, take your manure from the heap in which it has been rotting and spread evenly over the soil before working it in thoroughly. With chemical fertilisers, it is important to apply according to the manufacturers instructions and to make sure it is evenly distributed. Once you have spread it, it should be mixed thoroughly with the soil to avoid harming fledgling roots.
If you follow the guidance above, your vegetable garden will be well fed and, with a bit of luck, you should have a bumper harvest.