2009-04-30 / News

Increasing vegetable yields

The Island Garden
By Roger Marshall

According to a Garden Trends report, 74 percent of gardeners say they will grow fruit and vegetables this year. For the first time ever, that's more people concentrating on growing vegetables and fruit than tending their lawn, traditionally the item upon which people spend the most money.

The reason for this increase in vegetable growing is that consumers want to cut emissions (it has been estimated that the average vegetable has travelled 1,500 miles before it gets to your table), get better taste, eat fresher, less contaminated fruit, and eat food that they know has not been hit with pesticides regularly. Not only that, but saving money in this economic climate is a big incentive for many young families.

So how do you get increased yields from your efforts? First, you need to make sure the soil is in tip-top shape. That means lots of organic matter, good tilth, lots of worms, and a soil that will produce lots of food for your table.

You will also need to adapt parts of your garden to the type of vegetables that you plan to grow. For example, if you want to grow leeks, onions, cabbages, squash and corn, you should put lots of manure or fertilizer on the garden to nourish these heavy feeders. But, you do not want high nitrogen fertilizer around your potatoes, tomatoes, and peppers. If you put manure around them, you get lush green plants but very little fruit. Around these plants you'll need fertilizers with high potash and phosphate levels. Around fruit trees you'll need a more balanced fertilizer.

Organic matter

Organic content comes from the addition of mulches and compost to your soil. Many gardeners simply dig plant residues into the soil to put back the remains, but this is not a good idea because diseased plant residues can spread more disease. The best way to increase organic matter is to make your own compost or buy it.

Good tilth

Good tilth is the gardener's way of saying the soil has good structure to sustain biological growth, maintain a diverse number of insects and animals, and to promote good health of the animals it sustains. In simple terms it means being able to plunge your hand into the soil and feel the organic matter, the crumbly soil structure and find beetles and earthworms living in it.


Worms tend to aerate the soil and help to give it good structure. A healthy soil has lots of worms, but worms function best in soil with lots of organic matter, so having one encourages the other.


Fertilizers encourage growth, but too much fertilizer can burn the plant and cut down its growth or even kill it, so only use the specifi ed amount of fertilizer on your plants.

When using fertilizer look at the numbers on the side of the package. There are three numbers to be concerned about and they are listed as N-K-P - that is, nitrogen, potassium in the form of phosphate and phosphorus in the form of potash. These numbers give you an idea of the amount of each element in the fertilizer. For example, fruit tree fertilizer has the numbers 7-3- 3. This says it is a more balanced all-round fertilizer. Lawn fertilizer may have 30-3-10 to promote fast growth of lawn grass. Onion fertilizer is more balanced at 10-20-10 to encourage good growth but the generation of large bulbs.

By now you may have figured that a fertilizer that has a high N for nitrogen number helps to promote fast green growth, the middle number, K, helps to promote flowering and fruit, while the last number also helps to promote fruit and strong roots systems.

How do you tell if your plants are deficient in fertilizer? Look at the leaves. Yellowing leaves and a light green plant usually indicates low nitrogen levels. Very dark green plants often with a reddish tinge may have a phosphorus defi- ciency. Yellowed or yellow-brown leaf tips is usually a sign of low potassium levels. Remember, too, that these signs can be caused by other deficiencies, but if you see any of them, it is not a bad idea to fertilize with a full spectrum organic fertilizer.

Acidic soil

Then we come to how acidic your soil is. Many plants like acidic soils like we have around here, but cabbage and broccoli prefer slightly less acidic soils so a judicious application of lime in fall where you are going to plant brassicas the next year is in order. Lime is not a fertilizer, but it helps plants to take up fertilizers better, especially lawn grasses.

Tuning your soil to suit the plants you intend growing is nothing new. It has been going on for thousands of years, but to get increased yields you should be aware of some of the advantages of the judicious use of fertilizers and organic matter.

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