In organic farming, using alternative planting techniques can improve a crop’s performance dramatically. Organic vegetable grower, Jane Griffiths, shares some ideas.
The major techniques are interplanting, companion planting, succession planting and vertical planting. Growing two or more types of vegetables in the same place at the same time is known as interplanting. Jane Griffiths, of Johannesburg, points out that one shouldn’t plant crops that compete with each other. Crops usually compete if they have similar root systems or a similar shape.
Before embarking on interplanting, determine whether the crop is a long-season (slow-maturing) or short-season (quick-maturing) crop. Plants such as carrots and radishes can be planted at the same time because the radishes are harvested before they begin crowding the carrots. Shade-tolerant species such as lettuce and spinach may be planted in the shadow of taller crops.
You can interplant in alternating rows, by mixing plants within a row, or by distributing various species throughout the bed. It’s important to keep a record of where each crop is planted if the beds contain a variety of plants.
The right combination of vegetables and beneficial plants must be planted together. Companion plants, together with beneficial insects, are a farmer’s best biological form of pest control. Griffiths explains that some companion plants are dual purpose as their leaves repel pests and the flowers attract beneficial insects.
Others have a very important function as accumulators of nutrients such as nitrogen and potassium. “Try to plant nutrient accumulator plants, as they can supply nutrients to vegetables that could otherwise not access it,” she says.
Planting legumes next to certain vegetables will help to accumulate nitrogen.
Most vegetables have distinctive shapes that harmful pests can identify. Griffiths suggests farmers grow shape-shifting plants to disguise vegetables and confuse pests, for example, cabbages planted next to nasturtiums.
Companion planting is different from monoculture, which prefers long rows of evenly spaced vegetables. This method is actually not suitable for smaller gardens as the distance between rows takes up too much growing space.
“Monoculture tends to invite pests because they can see the plants. Disease also spreads more quickly.”
Griffiths says that although it is easier to harvest crops planted in rows, this is less of a factor if beds are small (roughly the size of a door).
This is a form of crop rotation, which prevents the soil being depleted. One of the best ways to do so in a small space is to have crops from different families following one another in the same patch of ground. For example, start with radishes, follow with tomatoes and then spinach. Farmers could also plant a faster-growing crop simultaneously with, or between, successive plantings. This is a good way to maximise space.
Vertical planting makes the most of limited space, Griffiths says. Instead of growing sprawling vegetables such as butternut, runner beans, tomatoes and cucumber on the ground, use a tripod.
The vegetables are lifted off the ground, which improves air flow and reduces the threat of disease.
A variety of materials, such as wood or bamboo poles, can be used to construct the tripod. Griffiths points out that although metal structures may be more durable, they are often not suitable as the material can conduct heat and burn the vegetables.
The tripod must be sturdy and firmly anchored in the ground to prevent it falling over. The legs should be about 1,5m apart, 2 – 3m high, and be supported horizontally by cross beams. Be careful not to compact the soil around the area where the tripod is being constructed. Wooden planks placed on the soil will stop this. Remember that vertical planting will cast a shadow on the rest of the bed, so plan the tripod’s position to ensure that sun loving crops are not in the shade.
An inexpensive irrigation device can be installed at its base. Build up a large mound of soil below the tripod, enrich it with well-rotted manure and compost, and then bury a nursery pot or bucket in the mound (ensure that it has drainage holes). The bucket should be raised slightly above the soil. Next, plant the crops around the pot. This method will make it possible to water the roots by periodically filling the bucket with water. The water will trickle out when needed, thus preventing water wastage.
“If you can’t afford a sprinkler system this is also an excellent way of watering the rest of the beds,” she says.