A few simple precautions will ensure that your garden makes it through the summer, says Nick Leech.
For many UAE gardeners, summer is a time to batten down the hatches, turbocharge the sprinkler system and retreat indoors. However, if you can stand the heat, there is also still time to complete those essential tasks that will help protect your garden from summer's excesses. Rather than being a time of inactivity, summer is also a time when experienced gardeners and novices alike can learn more about the foibles of their plot, take stock and plan for the gardening a year ahead.
Prepare and reflect
For the garden blogger and dedicated home vegetable grower Shumaila Ahmed, now is the time when a lot of the hard thinking and hard work in her Dubai garden really begins.
"You have to really weigh up the cost of watching something grow. When the summer starts to bite, plants become stressed and more susceptible to pests and diseases," Ahmed explains. "This makes me very ruthless about cleaning, tidying up and getting get rid of diseased plants and potentially infected soil that might contain eggs or larvae. I wash my containers, cages and stakes and store them away in a place where the sun can't get to them."
Cleaning your pots each year is a great way of preventing the transmission of fungi, bacteria and disease from one planting season to the next. A sure-fire method for sterilising terracotta is to bake pots in an oven at 100°C for an hour. Sadly, this method only really works with small and medium-sized pots and it can put your kitchen out of commission for quite a while. Just remember to let the pots cool slowly until they reach room temperature before moving them.
Best investment: shade
It is always best to move any tender plants to an area where they will be sheltered from the worst excesses of summer sun. This is easier if you are a container gardener, but if you cannot move your tender plants, learn a lesson from the nursery experts and protect them with a shade cloth instead. "There are lots of different shade cloths available that vary in their level of shade, from 40 per cent right up to 70 per cent," explains Hussam Ali, manager of Al Foah Nursery in Al Ain. "If your plants are well established, then a 40 or 50 per cent shade cloth should be enough. However, if your plants are younger or delicate, then you may need 60 to 70 per cent shade."
Successful irrigation
Whether you have a lawn, garden beds or containers, now is the time to stop guessing about irrigation and to start giving your plants the water they actually need, as Ali explains. "To get your watering right you really need to understand two things: the water requirements of your plants and the media they have been planted in. It might be a water-retentive peat-rich, coco-fibre compost, or perlite. Even if they are planted in free-draining sand, some drought-tolerant species will not need to be watered every day because they can tolerate the summer conditions here."
For Ali, the biggest problem is actually giving your plants too much water, rather than too little. "Under-watering will not kill a plant but overwatering will kill it very quickly," he says.
Overwatering can also cause saturation and the leaching of nutrients from your soil. Saturated soils can starve roots of the air they need for healthy and effective growth, and roots suffocated in this way will lose the ability to absorb the water a plant needs, producing the same symptoms as under-watering. When this occurs, plants can enter a vicious spiral, often accompanied by fungal and bacterial root rot, which frequently results in death.
To water intelligently, think about irrigation in terms of the amount of time it should take to successfully water each plant. To establish this, keep the tap on until the water makes its way down to your plant's root zone, the area where they need moisture most. During the heat of summer, you should also inspect your soil or compost to see how quickly it dries out, as this will tell you if you need to schedule a second or even a third watering each day.
If you're watering a lawn, you will also need to provide a deeper watering a couple of times a week that will soak down past the root zone. Not only will this keep the soil hydrated, but it will help to make your plants become more drought-tolerant by encouraging their roots to grow downwards into soil that stays damper and cooler for longer.
The right bedfellows
Whether they are in pots or beds, drought-tolerant plants will suffer in damp soils and vice versa, so hydro-zoning, or grouping your plants according to their irrigation needs, is another technique that will help you to achieve irrigation success. It also makes life considerably less complicated, whether you are using an automatic irrigation system or watering by hand.
Mulch
Applying a dressing of stones, gravel, sand or bark to the surface of your pots and beds not only helps to keep soil and roots cool, but reduces the amount of water lost through evaporation as well. Mulches are like one-way doors that allow water to flow downwards toward the soil but prevent it from travelling back up again. If the underlying soil has a higher water-holding capacity than the surface, water is more likely to stay in the root zone until your plants require it.
Organic mulches, such as bark or wood chippings, are preferable to stones as they allow the soil to breathe and can be worked into the soil as a conditioner once they have decomposed. However, because they are absorbent, they will take some of the moisture from the surface of your soil. Make sure you water for long enough to ensure enough water actually penetrates the soil.
To feed or not to feed?
Many plant species enter a period of dormancy during summer, so it would be a mistake to feed them now. Excess growth, particularly of young fleshy stems and leaves, increases the rate at which plants lose moisture and reduces their ability to withstand drought. Some plants, however, such as warm season turf, flourish during the summer and will require regular feeding. So, too, will plants that display signs of chlorosis - a yellowing of the leaves - the result of nutrients being washed from the soil by regular irrigation. Check that the yellowing isn't the result of pests or diseases and apply Sequestrene or iron chelate to chlorotic plants.
Excessive wind?
In most cases, the kind of damage associated with exposure to hot, drying winds is insufficient to kill an otherwise healthy plant. However, a plant's recovery and survival will ultimately depend upon a correct diagnosis of your plant's distress. Is the plant suffering from wind scorch, or is it actually being overwatered or suffering from heat reflected off a nearby wall?
If you cannot move affected plants, try to erect a screen that will act as a windbreak. This should be permeable enough to allow gusts of air to pass through it at a reduced speed, but not so solid that it actually exacerbates the problem by creating turbulence around the plants you are trying to protect.
After a sandstorm, remember to rinse any accumulated sand from your plants' leaves once the bad weather has passed.
Plan ahead
Now is the time to reflect on this season's successes, learn from your mistakes and consider what's necessary to make the next season a horticultural success. A midsummer tour of your neighbourhood is always useful, as this will allow you to learn from your neighbours and to establish exactly what grows well, where and why.
For more information and advice, contact Hussam Ali at Al Foah Nursery, Al Ain (03 783 2102)
Tips on year-round vegetable growing in the UAE can be found on Shumaila Ahmed's blog Dubai Veg Growers and her Facebook page of the same name
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