|Updated : 21/9/2014|
Growing Vegetables in SA
Cool Season, warm season and intermediate crops
When growing vegetables it is important to understand that there are cold season crops, warm season crops and intermediate crops.
Sowing times may vary slightly from region to region, so check with your local garden centre for the exact sowing times and follow the sowing instructions on the back of your seed packet. Some vegetables in the intermediate group tend to `bolt' to seed if sown out of season. In subtropical climates many warm season plants are grown almost all year round but cool season crops might only have a very short growing season or none at all. Modern hybrid seeds allow many crops to be grown out of season so check your varieties carefully before purchasing your selection.
Perennial vegetables like horseradish, artichokes, rhubarb and asparagus are vegetables that you plant once and they keep feeding you for many years. Therefore, it is essential that you prepare the soil well, to the requirements of the plant. Choose a sunny position that won't get shaded by other plants over time. Some perennial vegetables, like asparagus will need a season or two to develop strong roots before a bumper crop can be harvested. Remember to feed and water your plants regularly for best results.
Root seed and leaf crops
Vegetables are also divided into three groups according To which part of the plant is eaten. Fruit and seed crops like peppers peas and beans; leaf and stem crops like celery, mustard and lettuce and root crops like beetroot carrots and turnips.
The three groups of root, seed and leaf crops provide guidelines on the correct fertiliser to choose. The three major nutrients are nitrogen, phosphorus and potassium. All fertilisers are labelled, giving the percentage of these three elements.
The figures in brackets at the end of this ratio give the actual amount of food in the bag. Therefore (22) means that only 22% of the contents of the bag contain fertiliser. The remaining 78% is an inert carrier such as gypsum. These carriers make it easier to spread the fertiliser and prevent burning from over fertilisation.
Nitrogen is needed by all vegetables but especially in leaf and stem crops. Too much nitrogen on fruit and root crops can produce too much leaf growth at the expense of flowers and fruit. Phosphorus is essential for the development of roots, flowers and fruits. Potassium is essential for flower formation and balances the salts in the sap of the plant, thereby helping to protect your plants from disease.
2:3:2 is a good general—purpose fertiliser for vegetables. Never allow granular fertilisers to fall on the leaves and stems of your vegetables as this could burn them and always water the beds thoroughly after fertilising.
Liquid fertilisers are a good alternative for small vegetable patches and container plantings. They are a safe and effective way of providing your plants with the best nutrient supply without harming them or increasing the soil's acid content. Liquid organic fertilisers help plants overcome the tension involved in transplanting or during cold weather, or a dry season. They are applied through spraying or direct application to the soil around the plant. When sprayed directly onto the plant the nutrients are absorbed faster.
There are several types of liquid organic fertilisers available and the most common ones are made from fish emulsion or kelp, earthworm castings and bat guano.
If you want to convert to organic gardening but your soil is depleted you will have to put in a little extra effort in the beginning. Start by regularly mulching your beds with organic matter like compost and foliar feed your plants regularly with organic liquid fertilisers like Nitrosol.
Make your own liquid compost.
This can be easily made by filling a Hessian bag with compost or kraal manure and placing it in a bucket of water to steep for a week or two in a sunny position. Stir the mixture daily. Dilute the water until it looks like weak black tea and water it around your plants.
With foliar fertilising you are spraying the food directly onto the leaves of your pants and it is quickly absorbed. This will help prevent pant deficiencies and encourage strong, healthy growth that is more resistant to pests and diseases.
In simple terms, crop rotation is a system of planting which ensures that vegetables of a similar character do not follow one another on the same piece of ground year after year. Different crops require different nutrients and by changing the position of the crops you will maintain a balanced soil. There are many theories on crop rotation and gardeners apply various methods. There are no hard and fast rules and if you are growing organically, do not plant huge beds with a single crop, as this makes the crop more susceptible to pests and diseases. Plant smaller beds interspersed with other vegetables and herbs as companion plants. The most important points to consider when planting in this way, is to group plants together that have the same watering and feeding requirements. Herbs and other companion pants can be planted into pots and placed near the crop if they require less watering and feeding. Prevent the spread of fungal diseases In South Africa There is a natural rotation between cool and warm season crops and many crops cannot be grown successively because of their seasonal requirements. Crop rotation will help prevent the spread of fungal diseases and the build up of insect pests. If your garden is very small it is not necessary to practice crop rotation as long as the soil is well maintained and you feed your vegetables regularly.
An easy method of practicing crop rotation is to divide the vegetable garden into three beds, one for leaf and stem crops, and another for root crops with the last one for fruit and seed crops. Every season the crops are rotated so that by the fourth year they will be planted into the same bed again.
Another method of crop rotation is to plant the same families of vegetables together. In this way crops that need similar feeding and watering requirements are grouped together. In addition deep rooting crops are alternated with shallow rooting crops. As far as possible crop "families" are kept together. For this reason we put turnips in with the cabbage family, as they are closely related.
Crops can also be grouped according to their feeding requirements. Plant heavy feeder's together, medium feeder's together and light feeder's together.
Preparing and planning a vegetable garden
Preparing and planning your vegetable garden is the most important task. Vegetables must grow quickly for optimal flavour and quality so prepare the beds well. They love a sunny site with at least four or five hours of sun a day, especially in the winter months. Sow your vegetables in rows running from east to west to optimise sunlight. Plant taller crops like tomatoes at the southern side of the beds so that they do not cast shade on the other lower growing crops.
For successive crops, sow small quantities of seed at a time. A common mistake amongst gardeners is to sow or plant too much at one time. Leave one bed empty for the next planting. Try to group crops together that will mature at about the same time so that they can all be harvested together, allowing you to prepare the bed for the next sowing or planting.
For healthy, vitamin packed vegetables that are less susceptible to disease a good friable, humus filled soil is essential. Every plant you grow removes minerals and trace elements from the soil and if you don't replenish them your crops will produce lower yields. Crops like squashes will bear for the whole growing season and should be planted apart from other crops. Perennial crops like rhubarb should be planted in beds where they can grow undisturbed for up to two years.
Vegetables will grow better if protected from strong wind but need a good air flow around their leaves. Fine mesh netting, wooden trellises etc will break the wind without causing wind turbulence. A solid brick wall will force strong wind upward, causing turbulence on the other side. Windbreaks of shrubs or trees can be planted but plant them well away from the vegetable patch so that they don't throw too much shade.
Preparing the beds
Thoroughly dig over the entire bed, adding lots of compost and 100 grams of organic 2:3:2 fertiliser per square meter.
Rake the bed level, water well and allow the bed to lie for at least a couple of days before sowing seed as certain big seeds like beans can be damaged by direct contact with fertiliser.
The perfect soil for growing vegetables is a loose crumbly well- drained soil that still retains moisture and nutrients.
If your soil is very sandy add lots of compost and if you have clay soil, grow your vegetables in raised beds.
Planting your vegetables in specially prepared trenches is a method long recommended by practitioners of permaculture. It works very well and allows for water conservation, as grey or rainwater can be re-cycled by directing it into the trenched beds. It promotes healthy roots and provides nutrients as well as encouraging earthworms. Trenching is labour intensive To start with but produces high yields and can be done in a relatively small space.
Dig a trench to the length you require and to a depth of 35 to 50cm, putting the soil to one side. Half fill the trench with organic materials like kitchen waste, papers, cardboard, egg boxes, wood—fire ash, lawn clippings, and stale bread, wood-shavings, leaves, old flowers and manure. Allow this mixture to decay and become compost before mixing the remaining soil into this compost to make a slightly raised mound—shaped vegetable bed. After planting, mulch the entire bed and add more organic matter like compost or mature kraal manure prior to each new planting. If moles are a problem line the bottom of the trench with broken glass. This technique is used when making bowling greens.
The disadvantages of raised beds are that they will dry out faster than in- ground beds, especially during hot sunny weather and on windy days. Soaker hoses and mulches can cut down on the amount of water you use.
You can build a raised bed using a number of non-Toxic materials like planks, bricks, stones, or even old car tyres. If you are using wooden planks for construction; paint the outsides and leave the insides untreated. You don't want nasty chemicals leaching into the soil to be taken up by your vegetables. Avoid pressure-treated lumber and stay away from creosote coated beams. The life span of an untreated plank is about 6 years, depending on the wood used and is not bad considering all the advantages of this system.
When building your raised beds, do not make them too large or it will be awkward to tend to the vegetables growing in the middle. Rather construct several small beds.
Before building and placing your raised bed, dig The soil over at ground level To a depth of about 20cm, if your raised bed is also 20cm high, This will give you a Total depth of 40cm to grow your vegetables in and allow for better drainage. Fill the bed with good topsoil enriched with compost and manure. A well-constructed raised bed should last for years and soil fertility can be maintained by adding organic matter regularly.
Raised beds have been used for centuries and with good reason; they're better for many plants and they're easier on gardeners. Some garden centres may offer raised bed frames that snap together and can easily be taken apart. You can also build raised beds by simply building up the soil in rows to raise the beds.
Once your soil is in perfect condition it will be unnecessary to dig it over, or double dig your beds. This is vital if you want to practice organic gardening as digging the soil can destroy the texture of the soil and the beneficial micro-organisms that live there. Healthy soil will be full of earthworms so let them do the digging for you. They make deep tunnels in the ground that allow both air and water to penetrate, and help to work the nutrients down into the soil. Earthworm castings are rich in nitrogen, potassium, phosphates, magnesium and calcium and are always more acidly neutral than the soil from which they are formed, thus balancing the pH of the soil. Earthworms are the organic gardener's best friends.
Make your own compost with red-worms
Work with nature by recycling your organic household waste into compost and cut down on garbage going into burgeoning landfills. Red-worm composting is a method for recycling that can be practiced both indoors and outdoors all year round. There are a number of worm farms available commercially to suit individual needs; from large bins to small-stacked trays or hanging bags. If you prefer, you can make your own. Simply put, worm compost is made in a container filled with moistened bedding and red-worms. Add your food waste and the worms and micro- organisms will convert it into rich compost. Red-worms Eisenia foetida (commonly known as red wiggler or brandling) are best suited to worm composting. You can easily start with a few worms, reducing the food waste used, until your worm population increases. Suitable bedding materials are shredded newspaper and cardboard, shredded autumn leaves, chopped up straw, sawdust, palm peat, compost and aged manure. If you have the correct ratio of surface area to worms to food scraps, there is little else to do, other than adding food for about two and a half months. By then, there should be little or no original bedding visible in the bin and the contents will be brown with worm castings. The compost produced is excellent either dug into the soil or used as mulch.
To learn more fascinating facts about red worm composting and how to make your own worm farm visit www.redwormcomposting.Com
pH of the soil
The acidity of garden soil is referred to as its pH and is measured on a scale of 0 To 14, with 7 being neutral. Alkaline soil has a pH value above 7. Acid soil has a value below 7.
In simple terms, the acidity reflects the amount of calcium (i.e. chalk or lime) in the soil. This changes over time as it is leached out of the soil by rain etc. and by growing vegetables, this leads to increased acidity as time goes by. Clay soils hold calcium better than sandy soils and therefore they tend to be alkaline. Sandy soils tend to be more acid.
The high rainfall regions of South Africa tend to have acid soils and the areas with low rainfall, neutral or even alkaline soil. Vegetables need more attention, regarding the soil pH, than flowers or shrubs. Most vegetables prefer soil with a neutral pH of 7.0 to slightly acid soil; pH 5.5 To 6.5. Lime is used to make the soil less acid but should be applied one month before adding compost, manure or fertiliser and before sowing or planting. Lime should only be required every three or four years if you practice crop rotation and maintain a healthy soil. Improving your soil continually by adding compost and other organic matter will eventually correct nearly every kind of problem soil.
Inexpensive pH kits are available to measure soil reaction. Lime is traditionally spread on the surface of the soil for rain to wash it in but on medium to heavy soils, it is better to dig it into the topsoil. The amount of liming necessary will depend upon the type of soil, the actual pH and the desired pH; the wider the gap (for a given soil type), the more liming will be required.
Mulching is also essential as it prevents moisture loss, soil erosion, suppresses weeds and keeps the soil cool in summer and warm in winter. As the mulch breaks down it will feed the soil. Any organic matter like compost, kraal manure, leaves; grass cuttings, straw, etc. can be used as mulch. Mature animal manures are wonderful added to your soil but if you are growing organically ensure that the animals were not given hormones, antibiotics etc. In cool regions black plastic sheeting can be used as this will help to keep the soil warm.
To grow good quality vegetables they must be watered regularly so ensure that there is a permanent supply of water nearby.
It is a lot easier to get the watering system in place before you plant.
On both flat sites and those with a slight slope, furrow irrigation is a useful method for watering. This method of watering is especially good for tomatoes, squashes and other crops that are prone to leaf fungal diseases. Water droplets spread fungal diseases, so it is best to keep the leaves of these crops dry.
You can make your own drip irrigation system by making small perforations in a hose at regular intervals and lay it along the beds between the rows of vegetables. Connect the pipe to your tap and turn it on gently, allowing the water to slowly seep through the holes in the hosepipe. This method of watering is most effective and will water slowly and thoroughly.
Growing vegetables from seed
Most vegetables can be sown directly into the soil. Some crops like mielies, beans, peas and all root crops like beetroot and carrots do not transplant well and are best sown directly into rows. Prepare your beds as outlined on Page 9 and rake the bed over to a fine tilth.
Measure out your rows according to the spacing requirements of the crop. Tie string between two pegs inserted in the ground to ensure that the rows are straight.
Make a shallow furrow at the correct depth for sowing that particular crop. Never cover your seeds too deeply with soil, especially very small seeds. The general rule for covering seed after it is sown is to cover it to the same depth as the diameter of the seed. Fine seed is therefore covered lightly and larger seed is covered a bit deeper. When sowing small seeds directly into your beds, mix a small quantity of seeds at a time into a bowl of compost.
The compost provides bulk and will help you to spread the seed more evenly. Once the seed is sown, gently tamp down the soil with the flat end of a rake. Finally, water the area thoroughly with a fine spray.
Most vegetable seeds must be kept moist at all times until germination, which could take anything from one to three weeks, depending on the variety. Beans, peas and maize may fail to germinate if they are given too much water in the first few days after sowing and should not be soaked in water overnight, before sowing.
As the seedlings develop, it may be necessary to thin out overcrowded clumps as soon as the seedlings can be handled, removing small, weak or malformed seedlings first. A second or even third thinning may be necessary. Do this in the cool of the day. Protect small seedlings against snails, slugs and even birds.
One of the advantages of sowing seed into trays is that you can start sowing earlier in the season, because the trays can be protected from the elements. This method is also more hygienic and therefore more successful. If you are using old sowing trays wash them with hot soapy water to which a disinfectant has been added, to eliminate any fungal or soil-borne diseases that may be present. Fill the sowing trays with a good germination mix from your garden centre and water the trays thoroughly with a fine mist spray before sowing the seed.
Never cover your seeds too deeply with soil. The general rule for covering seed after it is sown is to cover it to The same depth as the diameter of the seed. Fine seed is therefore covered very lightly and larger seed is covered a bit deeper. Water the trays with a fine mist spray again, when you have finished sowing and don’t forget to label the Tray and include the date sown.
Place the trays in a protected, well-lit place away from direct sunlight or under shade cloth until germination. It is vital that the soil is never allowed to dry out totally until germination takes place.
You can cover your trays with a clear pane of glass to keep the humidify high and the moisture content of the soil constant. If the pane mists up too much, remove the glass for a while before closing it again. Remove the glass once the seeds have germinated.
Prick the seedlings out once they reach their first 'True leaf' stage and transplant them into seedling trays. Place the trays in a shady place and slowly expose them to more and more sunlight. Let them grow until they are big enough to be planted into the garden.
Successive sowing is the practice of sowing the same type of vegetable at certain intervals. Doing this will give you a much longer supply of your family’s favourite vegetables.
The secret to successive planting is planning, so keep a garden diary of what varieties were sown, on what dates, and when the next sowing should be done.
On your seed packet it will tell you how many days to harvest, taking notes on this will help you to plan your sowing cycle for a constant supply.
Keeping a diary will be very beneficial in seasons to come. You won’t have to rely on your memory to establish what worked and what could be improved on next season. Plus There's the bonus of having in writing what you grew too much of, and what you could have sown more of. Sowing early, mid-season and late varieties of your favourite vegetable will extend the length of your growing season.
Growing vegetables in containers
If space is limited you can grow many vegetable varieties in containers and window boxes as long as they receive enough sunlight. New hybrid seed offers dwarf or baby vegetables that mature early. These are ideal to grow in containers. Large growing vegetables like tomatoes climbing beans, peppers, marrows and pumpkins will need large pots 25 to 60cm in diameter and 25 to 40cm deep. For smaller vegetables use pots at least 15 to 20cm deep. Troughs can be used for baby carrots, radish, spring onions etc. If you are planting in old containers it is advisable to replace the soil every year or two. Thoroughly wash the container with hot, soapy water and a disinfectant, to eliminate any fungal or soil-borne diseases that may be present in the old soil.
It is vital that the containers drain well. Cover the holes with a layer of broken cracks, bricks or charcoal and fill with a good growing mixture that will hold moisture.
A good potting soil mixed with some compost works well and if extra drainage is required some washed river sand can be added. Sprinkle some organic 2:3:2 into the soil before filling the pots.
Never leave your pots standing in drip trays filled with water as this can lead to rotting.
Container vegetables must be watered and fed regularly. Liquid fertilisers like Nitrosol, KelPlus or Seagro are ideal, as They can be mixed into a watering can and will not burn your plants if applied correctly.
Companion panting is the art of natural gardening. Each plant has its own scent, which either attracts or repels insects that are in search of food or a suitable host plant for their eggs. Companion planting reduces and ideally eliminates the use of harmful insecticides and herbicides. Certain vegetables and herbs grow well together and help keep each other healthy and pest free. Other plants naturally repel each other and should not be planted next to one another. In the individual plant text I have included many tips on this fascinating subject to get you started.
Here are a few basics to begin with. Planting a wide variety of strongly scented herbs around the vegetable patch will help deter insect infestations and will also attract beneficial predatory insects; thus helping to create an ecological balance in the garden.
Prune the herbs often and bruise the twigs to release the scent; before scattering them around your vegetables. Yarrow and pineapple mint are good pest deterrents and feverfew has a spicy scent that repels a wide variety of insects.
Thyme and lavender keep a large variety of insects out of the garden and are ideal to plant around the border to the vegetable patch. Lavender varies in height and spread, so select your variety carefully. It also serves as a windbreak to the garden and will help keep ants away.
Most importantly; herbs will attract bees and butterflies to the garden. These are vital for the pollination of your crops. Dill will attract bees and gives off a scent, which promotes strong growth in neighbouring plants.
Comfrey should be cultivated in every vegetable patch as it is rich in vitamins, protein and especially potash. Harvest the leaves before flowering, dry them in the sun and use them as mulch around your vegetables, especially vegetables that are heavy feeders. To keep snails at bay, place the hairy leaves around susceptible plants.
Khakibos is extremely effective in chasing ants away and grows wild in the summer, often popping up in the vegetable patch. Cultivate this plant in a small patch and regularly chop the entire plant and place it around your vegetables and ant entrances. It can also be dried and used in the same way. If you do find an ant nest, dig it up and scatter the eggs out in the open for the birds to eat. A strong infusion of garlic in water, poured down the holes, will chase ants away.
Plant tansy in your garden and pick sprigs of the fresh plant to place around the ant's nests, both inside the house or in the garden. Spearmint and pennyroyal mint helps repel ants and aphids because the ants place the aphids on plants and dislike the scent of mint.
Brightly coloured petunias make excellent companions for all vegetables, especially cabbage, broccoli, kale, potatoes, beans and squash varieties and act as a tonic to neighbouring plants.
Ants are rarely a problem in a well- maintained organic garden. To deter them you must control| your aphid, mealy bug, white fly and scale populations on which they feed by planting lavender, thyme, spearmint, pennyroyal and Tansy around the vegetable plot. Improving your soil by digging in compost also helps.
Legumes such as peas, beans, soya and peanuts are soil-builders and suitable companions for heavy feeders such as tomatoes, cucumbers and sunflowers.
Rosemary, lavender, sage, Thyme, Tarragon and lemon balm are all useful ante insect agents in the vegetable garden. Yarrow repels insects and increases the aromatic quality of other herbs.
Oregano repels aphids, the cabbage fly and many other insects with its scent, so plant it in several places in the vegetable patch.
Snails and slugs can be baited by hiding wheat or bran under a cabbage leaf during the day. Collect and dispose of the snails in the evening.
Plant rue around the border of the vegetable patch to keep cats away from your garden but do not plant it too near to your crops as most plants do not like growing near rue because of its powerful smell.
Plant marigolds in rows in-between your vegetables in summer and calendula in winter. The roots of calendula and marigold release a chemical that will help to control certain soil nematodes and promote healthy growth in plants.
Ladybirds are beetles that are easily identified with their small round bodies and are usually red with black spots or the other way around. There are many more species in this family than most people realize and not all of them are good in the garden. The shiny, common garden variety with red or black dots eats aphids (plant lice) and is good in the vegetable garden. They breed rapidly and gobble up your aphids with relish.
Nasturtiums are rich in sulphur and Vitamin C. Allow them to grow on your compost heap and dig them into the soil as a green manure. The sulphur will work against bacteria, while the Vitamin C will strengthen plants.
Add cuttings of herbs such as comfrey, yarrow, dandelion, valerian and tansy to your compost heap. These herb activators will make your compost heat up faster. The herbs will also add valuable minerals to the soil. Human urine is a great compost activator and also good for trees and shrubs if diluted about 10:1. Old yeast mixed with water and sugar will also aid decomposition.
Marigolds are used as a bait plant for red spider, thrips and Astylus beetles. Pull out the infected bait plants and throw them away.
The French marigold called `Tangerine' (Tagetes patula) is much more effective than the African marigold (T. minuata).
Bait plants like Nasturtiums helps control scale between fruit trees and vegetables as well as aphids, (especially the black aphid), snails and slugs. The insects attack the nasturtiums instead of the crop growing nearby. Nasturtiums self seed prolifically and the insect infested plants can be pulled out and discarded, allowing new seeds to germinate.
To improve your soil, without deep digging, grow a green manure
crop. These crops have extensive root systems that will loosen and
enrich the soil. Sow rye grass, oats or sorghum, mustard,
nasturtiums or calendulas and dig them back into the ground when
they start flowering. The roots of legumes like peas; beans,
alfalfa, clover, vetch, lentils and lupins Take nitrogen from the
air and fix it in the soil. They are often grown as nitrogen fixers
and are cut down to ground level as they start to flower and the
entire plant dug into the Topsoil and left to decompose. High
nitrogen feeders are then planted into the bed.