Heat wave help

recycled juice bottle

 

With high temperatures predicted for many areas of mainland Australia this week, I would like to remind you that you can find tips on helping your garden to survive extremely hot temperatures here: Heat wave protection

Frost damage

frostonplants Last night was unusually cold, and we had frost where we had not had any for many years. If plants in your garden have been damaged by frost, please resist the temptation to prune back the damaged parts. They may look unattractive, but there are probably more frosty nights to come, and the damaged parts will protect the plants from further damage. Pruning damaged plants is best done in spring after the weather warms.
If you have plants that are frost intolerant, you can protect these with a temporary cover. See: Cold and frost protection.
Seedlings are very sensitive to frost. You can provide protection for these by making a simple cloche. See: Cloche for seedlings.

Moving trees and shrubs

Sometimes it is necessary to move an established tree or shrub. Deciduous plants can be moved in winter or early spring, and evergreen plants in spring. This is best done in two stages if you have to move an evergreen plant, but sometimes situations arise, due to weather conditions or moving house where a shrub or tree has to be moved urgently.
This advice is for moving trees and shrubs small enough not to require the assistance of mechanical equipment.
dripline1

  1. Dig a deep trench around the plant you want to move, using a sharp spade to cut through the roots. The trench will usually have to be dug inside the drip-line of the plant, otherwise the root ball will be too large to handle. The drip-line is the area of soil directly below the outer edges of the foliage – where rain runs off the leaf canopy onto the soil. This is where the feeder roots usually lie.
  2. Water the area thoroughly, but do not apply fertiliser. Then prune back the foliage, or remove whole branches in the case of frangipani. This is necessary to compensate for a smaller root ball, so that the plant will not suffer water stress.
  3. If possible, leave evergreen plants in position for about a month, watering it regularly. This will help the plant to produce some feeder roots within the reduced root ball area.
  4. When ready to move the plant, make sure the soil is damp. Get a large piece of hessian, shadecloth or weed mat and some cord. This will help to keep the root ball intact during transplanting. A trolley, or tarpaulin or another large piece of strong fabric will help to use as a sled to drag the plant to its new planting position if the plant is too large to lift into a barrow.
  5. First dig the hole where the plant is to be positioned. Fill the hole with water. This is important for two reasons. How quickly the hole drains indicates whether drainage is good or you will need to plant the tree or shrub in a raised mound. If the surrounding soil is not damp when you transplant, the water you apply after planting will be drawn away from the root ball into the surrounding dry soil, and the plant will look stressed several days after planting.
  6. Work the spade around the trench dug previously, easing the spade further and further under the root ball until you have cut through all the roots.
  7. Place a clear mark on the north-facing side of the plant so that it will be positioned in the same orientation.
  8. Ease the fabric gently under the root ball. It will be much easier if someone helps by slowly tilting the plant to one side. Gather the fabric around the root ball and tie with cord.
  9. Carefully transfer the plant to the new hole positioning it at the same level it was planted previously. Untie the fabric and gently ease it out from under the root ball.
  10. Fill the hole with soil, adding some compost, if available. Do not trample the soil around the plant. Water thoroughly to remove any air pockets around the roots, and apply a 5 cm layer of mulch around the plant, keeping it a hand span from the trunk. Job done.

** Please note: Moving Eucalyptus taller than 45 cm, or other plants that have tap roots is often unsuccessful.

Cloche for seedlings

cloche With very cold weather set to continue over much of Australia for some time, gardeners can protect young seedlings with an easy-to-make cloche. This simple structure named for the French word for ‘bell’ keeps plants warm on chilly nights and can be easily ventilated so that they don’t get too warm during the day. When the nights are milder, the structure can be easily folded and stored until it is needed again.

Instructions for making cloches can be found here: Cloche for seedlings.
** And remember to leave frost-damaged parts on shrubs until all risk of frost has passed. They may look unattractive but the burnt portions are protecting the plants from further damage.

Watering in drought conditions

This week, two readers have asked me about garden problems caused by lack of water. As you know, it is extremely difficult to keep gardens well-watered in drought conditions. However, as plants can only absorb the nutrients they need for healthy growth and ripeness of crops as water-soluble ions, inadequate water is the cause of a wide range of problems, including pest attack.

Bare soil in garden beds and around trees, shrubs and vines allows a lot of soil moisture to be lost to evaporation. A 5 cm layer of organic mulch over beds and around larger plants (keeping it a hand span from the trunk) will prevent water applied to the soil from being wasted. Lawns are greedy and as their roots are close to the soil surface, they take water and nutrients intended for fruit trees and favourite ornamentals. Keep lawns beyond the outer canopy of trees and cover the area under trees with mulch.

wtrbttle.jpg A method that we have found very helpful to water mulched beds is to use plastic soft drink and juice bottles to funnel water through mulch directly to the root area of susceptible plants. This is a quick and very efficient way to hand water during drought, water restrictions, heat waves or windy weather. Limp tomato seedlings will freshen up in about 10 minutes after watering by this method.
Simply cut off the base of each container, remove the lids and bury the necks of the containers about 8 cm deep near outer edge of the foliage of plants. Large shrubs may require several containers. Pour water into the container until it begins to drain slowly – an indication that you have dampened the soil in the root area.

Seedlings and pot plants are usually the first to suffer during heat waves, and you can find advice on how to revive stressed pot plants here: Pot plant stress

False spring

cloche Chilly days and nights after a brief period of perfect gardening weather occur every year in many parts of Australia. Australia is the only place where spring is said to start on the first day of September. Everywhere else, spring starts at the equinox when day and night are of equal length. This year, the spring equinox occurs on September 23rd.
Unfortunately, Australia’s deviation from world-wide practice tricks some gardeners into planting out seedlings while nights are still longer than days and soil is still too cold for root growth of warmth-loving plants. The problem can be solved by placing this simple cloche over beds that contain cold-sensitive seedlings. See: Cloche for seedlings.

Windy weather update

Transpiratiion Predictions are for more cold, windy weather on the way. Keep a close watch on your garden as wind can dry out soils faster than summer heat, resulting in cell collapse of soft tissue plants. To discover why this happens and how to protect your plants, see: Windy weather
Seedlings and many vegetable crops are vulnerable to wind damage in winter and early spring. Ripening citrus are also easily damaged by strong winds.

Heat wave protection

Some parts of Australia are enduring extremely hot weather and, apparently, there is more to come this summer. Periods of intense heat can cause scorching in many gardens.
Although European-based garden texts recommend full sun for most vegetables, where summers are hot and air pollution is low, full sun can result in sunscald. While Australian natives have evolved to restrict loss of water through leaves in hot, dry conditions, very hot plants, especially those that originated in cooler Northern Hemisphere regions – such as most of our vegetables and fruits, lose a lot of water through their leaves in an effort to keep cool, in a similar way to humans perspiring.

A bit of shade
shdeclth Providing some light shade during the hottest part of the day can prevent sunscald on susceptible crops, and, by keeping the plants cooler, reduces their water consumption, an important consideration where water restrictions apply. We use lightweight, knitted shade cloth, supported by arches made from 38 mm irrigation pipe attached to garden stakes or star stakes, or you can use old light-weight curtains or sheets.
Each canopy is positioned to allow morning sun to reach plants, yet not restrict air flow around them. Poor air flow (such as in fully enclosed areas) can produce conditions suitable for some fungal diseases to establish. Instructions for making these can be found in the post Sun and heat protection.
However, in an emergency, any old curtains or pieces of lightweight fabric will do. Tie the corners to garden stakes to provide some relief for garden beds during the hottest part of the day.
If possible, move potted plants to a shaded area of the garden, and group them together. This provides more humidity around the plants, and reduces their water requirements.

Water is essential
wtrbttle.jpg Adequate soil moisture is essential for your vegetable garden to maintain good growth during heat waves. Mulching garden beds is very helpful. A method that we have found very helpful to water mulched beds is to use plastic soft drink and juice bottles to funnel water directly to the root area of susceptible plants. This is a quick and very efficient way to hand water during water restrictions, heat waves or windy weather. Limp tomato seedlings will freshen up in about 10 minutes after watering by this method.
Simply cut off the base of each container, remove the lids and bury the necks of the containers about 8 cm deep near outer edge of the foliage of plants. Large shrubs may require several containers. Pour water into the container until it begins to drain slowly – an indication that you have dampened the soil in the root area.
Seedlings and pot plants are usually the first to suffer during heat waves, and you can find advice on how to revive stressed pot plants here: Pot plant stress

Water for wildlife
Birdbath Don’t forget to provide water for birds and bees that visit your garden. A bird bath, or containers of clean water positioned where cats and dogs can’t reach them will provide relief for the insect-eating birds and the bees that pollinate your crops. Chlorinated pool water is toxic to these helpful creatures. A container of water under shaded foliage will be appreciated by your resident frogs too.

Limiting frost damage

Some gardeners may not be sure whether they are in a Temperate or Cool climate and, where frosts occur, the position of a property within a neighbourhood (the microclimate) can affect how much frost may affect your garden. The diagram below indicates where frost is more likely to affect parts of your garden.
The position of garden beds can also have a marked effect on the amount of plant damage that frosts cause. Cold air, like water, always flows downwards; anything that blocks the downward flow will result in frost damage in that area. Buildings, solid fences and shrubbery, and flat land at the bottom of a slope can all allow cold air to pool, and plants in these areas are more likely to be damaged by frost.

frostareas

In temperate climates areas that can be affected by frost, gardeners may find it helpful to use the guide for ‘cool climates’ in autumn and winter and use the ‘temperate climates’ guide in spring and summer because the world’s climate is changing and we have recently experienced harsher winters and hotter summers. It appears that the standard climate zones may have to be adjusted slightly in future. If unsure about what to plant at a particular time of year, a reputable local nursery will have suitable plants in stock and be able to advise you on what is best for your local microclimate. Be cautious though when buying seedlings from Australia-wide nursery chains, as some tend to send the same seedlings to stores in all climate zones.

By the way, advice to orient beds in a north/south direction to allow plants to receive ample sunlight comes from northern hemisphere gardening practices and only applies to very cool climates in Australia. Most areas of Australia get more than enough sun to ripen crops. In fact, plants can benefit from some relief from harsh afternoon sun in warmer climates during summer months. It is more important to position beds across any slope in the ground to ensure that all plants in a bed have equal access to water. Avoid placing vegetable garden beds under trees, as trees are very competitive for both moisture and nutrients.

Pot plant stress

Forecasters are warning of more hot days to come. During heat waves, pot plants become stressed more quickly than plants in garden beds, and your pot plants may not getting as much water as you think.
If potting mix dries out, the first sign may be complete collapse of a plant. If you water dry potting mix in the normal way with a hose or watering can, your plants may not be getting as much water as you think. This is because potting mix shrinks slightly when it dries, leaving a narrow gap between the mix and the pot. When you water, most of it runs into the gap and out through the drainage holes, leaving the mix around the roots still dry. Seedling punnets and smaller pots can be thoroughly watered by immersing the entire pot in a bucket half filled with water, or use a laundry tub if a lot of pots need reviving.
Water should come over the top of the pot. Leave the pot in the water until bubbles cease to rise. Short term immersion won’t hurt the plants. Then lift the pot allowing it to drain into the bucket or tub. This method of watering also works very well when your water supply for plants is strictly limited.
For pots too large to be immersed in a container, fill some large soft drink or juice containers and insert 2 or 3 neck down into the potting mix. Provide support if necessary and allow them to empty slowly into the mix. Re-fill the bottles and repeat watering until water is being drawn into the mix very slowly. If heat is likely to continue for some time, place some mulch or stones on the surface of the potting mix to slow evaporation.
Potting mix can become incredibly hot when pots are in full sun. During extreme heat conditions move pot plants to a cooler spot, including under trees. Grouping them together helps retain humidity around the plants and reduces water loss through the leaves.