Did you know that despite many years of gardening experts saying otherwise, it is not necessary to follow each crop in your kitchen garden with an entirely different one? And that watering your garden during the heat of the day will not result in the water droplets causing the sun's rays to scorch the plant's leaves? Read on to find out why…
Myth # 1: When practicing crop rotation, you should follow each crop with an entirely unrelated species
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Meyerton-based vegetable gardening expert Bill Kerr says, "Nothing could be further from the truth!" Gardeners think that they should plant certain crops one after the other which do not cause pests or diseases to affect the following crop. They might think they are doing the right thing if they follow root crops with leaf crops and non-leguminous with leguminous crops. This method assumes that each different species has a different set of pests or diseases. "But the truth is, there is one pest which overwhelms all other pests by far in its impact on our vegetables, and that is eelworm," says Bill.
"Eelworm damages more than 60% of homegrown vegetables and thrives in sandy soil in warm conditions. Crop rotation should, therefore, be determined solely by the resistance and susceptibility to this pest," he says.
"The first thing to do is to learn to recognise eelworm. Although there are a wide variety of eelworm species, the most important one is the root knot eelworm, a microscopic worm which penetrates root tips and causes swellings and distortions. These are readily seen on carrots where you find forked or lumpy carrots. Eelworm numbers build up rapidly and, if another susceptible crop follows, the results are disastrous. However, if you follow with an eelworm-resistant crop, you can starve the eelworm of food and their numbers will decline to manageable levels in the soil," says Bill.
The bottom line is that you should follow an eelworm-vulnerable crop with an eelworm-resistant crop, especially if eelworm symptoms are noticed on the roots. Crops which are resistant to most eelworm are leeks, onions, spring onions, garlic, cabbages, cauliflower, broccoli, certain varieties of tomatoes and lettuce. Highly susceptible crops are beans, beets, brinjal, carrot and Swiss chard.
"In addition to crop rotation, you can reduce eelworm populations by increasing the organic content of the soil with compost and manures, or a combination of both. In healthy soil conditions, many species of bacteria and fungi are able to survive and attack the eelworm. You can also plant marigolds in rotation and work them into the soil at flowering," concludes Bill.
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Myth # 2: Watering in the full sun on a hot day will burn the plant's leaves
'Burn' marks or brown patches noticed on plant leaves are usually caused by a fungus or bacteria and not by the water droplets magnifying the sun's rays and scorching the plant. This myth may also have come about due to watering with brak water (water that contains high levels of dissolved salts). As water drops evaporate from leaves, the salts left behind could cause leaf burn. Gardeners in those areas of the country where brak water occurs should rather use rainwater to water their plants.
The only reason watering during the heat of the day should be avoided is because it is better to irrigate your plants earlier in the day so as not to lose water due to evaporation. However, if plants are wilting due to lack of water on a very hot day, then it is of course best to give them a watering.
Myth # 3: Cleanly swept flowerbeds reduce the risk of pests in your garden
For decades 'cleanly swept' grounds were common practice in gardens. Gardeners thought flowerbeds with no leaf litter were more aesthetically pleasing and that fallen leaves blocked the air exchange in the soil. They were even under the misconception that this leaf layer depleted the soil of nitrogen, thus competing with the plants for food, and that keeping the ground 'clean' would reduce the incidence of ants, snails, slugs and rodents.
However, the blanket of leaves, twigs and faded flowers has an important role to play. This naturally spent organic matter – known as mulch – in nature is used to reduce evaporation, conserve moisture and prevent the soil from drying out. On soil that is cleanly swept, dew or water drawn up from the subsoil is wasted, because there is nothing on the soil to catch and hold it.
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Myth # 4: Digging over your garden soil is good for your plants
The reverse is true. It is better to avoid digging over (tilling) your garden soil. This 'no dig' method in fact improves soil structure because the living layers of soil are not mixed up and soil compaction is reduced. Conversely, digging over the soil grinds up soil thereby destroying its structure. In nature a healthy organic soil structure may take millions of years to form. Soil with a good structure acts like a sponge – holding water, creating a channel for rainwater to enter the soil, and making calcium, magnesium, potassium and other nutrients available to plants.
Myth # 5: Plants in a garden setting will not become invasive
Definitely not true! Not all garden plants behave themselves, and many have, in fact, become a problem by spreading into surrounding areas, especially sensitive natural environments. Plants which are described as 'fast-spreading', 'self-sowing' and 'tolerate poor soil' are also indications that they may become invasive. Many ornamental plants that were introduced into this country by horticulturists many years ago have now become problem plants.
Gardeners need to be aware of the different categories of invasive plants:
* Category 1: These plants that must be removed and destroyed immediately. Examples include Mexican ageratum (Ageratum houstonianum), fountain grass (Pennisetum setaceum) and Indian shot (Canna indica).
* Category 2: (Commercially used plants) These plants may be grown under controlled conditions only. Examples include St John's wort (Hypericum perforatum) and weeping willow (Salix babylonica).
* Category 3: These plants may no longer be planted, although existing plants may remain as long as their spread is contained. Examples include the orchid tree (Bauhinia variegata), St Joseph's lily (Lilium formosanum) and loquat (Eriobotrya japonica).
Try and eliminate invasive plants from your garden and work with your neighbours to ensure that they do not have invasives in their gardens which may spread to your area.
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Myth # 6: It is best to water lawns at night to avoid evaporation
In fact, watering your lawn at night exposes it to fungal pathogens, which thrive in cool, moist conditions and dark places. Watering your lawn late in the day or in the evening gives the fungus exactly what it needs to thrive and will cause your lawn to become diseased. Rather water your lawn early in the morning as this gives the grass time to dry out during the day, at the same time minimising water evaporation from the soil itself.
Myth # 7: Don't skimp on water for your plants
Most gardeners actually water their plants too much and excessive water can actually kill a plant by depriving the root system of oxygen. Landscaper Beverley Ballard-Tremeer says, "Most gardeners water too much rather than too little. With a few exceptions, providing good drainage for your plants is more important for their health."
When plants need to become established after transplanting, they should receive adequate watering. Even drought tolerant plants may need extra water until they are established. But in terms of general watering, the rule of thumb is to give your plants a deep watering once a week in hot, dry weather. "But," says Beverley, "remember that plants have varied water needs. Planning different watering zones in the garden – high water usage, medium water usage and low water usage zones – and planting accordingly will make correct watering easier and reduce your water bills."
Myth # 8: Plants must be fertilised many times during the growing season
On the contrary, some plants may be harmed by too much fertilising – for example proteas, leucadendrons and leucospermums. "Too much fertiliser or the wrong kind, such as fresh chicken manure, can burn roots or result in rapid but spindly growth," says Beverley. "Also, plants in the legume family, such as beans, peas, clover, lupins and acacias, fix their own nitrogen and should not to have it supplemented." If too much nitrogen is applied to plants, it will result in soft, lush growth which can make the plant susceptible to fungal disease and pest attacks.
The most important nutrients for plant growth are nitrogen, phosphorus and potassium and balanced fertilisers contain a mix of these three elements. It is best not to apply too much fertiliser as a lot of the nutrient value will end up washing away before your plants can use it. "Read the instructions on the fertiliser bag carefully before applying granular fertilisers or choose a slow release granular fertiliser where the nutrients are not made available all at once, but gradually over a period of time," advises Beverley.
Consider using organic fertilisers such as bonemeal and kelp, which contain much lower concentrations of nutrients that are released over time.
Sources: www.theinformedgardener.com, http://skagit.wsu.edu
Some other common myths:
- Place water bottles on your lawn to discourage dogs from doing their 'business' on the grass. This theory has not been conclusively proven. In some cases, pets may be deterred by the sound of the water moving in the bottle, if it is half-full. Or, sunlight reflecting off the water may be a deterrent.
- Break open used tea bags and scatter their contents among your plants to improve their growth. There is no truth to this myth! There is nothing in the contents of a teabag that stimulates growth. What the discarded tea bags may do is improve the soil structure.
- Hammer a nail into the stem of an avocado tree to 'shock' it into producing fruit. The nail does not 'shock' the plant into bearing fruit. Rather, it will supply minute quantities of iron, which is a micro-element needed by the plant for healthy growth. The nail might supply the tree with a small amount of iron for the plant's lifetime if left in the tree (if it doesn't kill the tree first!).
- If the leaves on your lemon tree are turning yellow, urinating on the plant will fix this! This is not true. Yellow leaves indicate an iron deficiency in the plant, and urine does not contain any iron – in fact it contains acid, which may negatively affect the tree.
