How to stop Frost Damage on plants?

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Understanding when and how a frost forms is the first step into preventing the damage it can cause. The worst frosts tend to occur on a cloud-free (clear) night with very little to no wind. Why is this? On still nights with no wind and no clouds, the ambient air cools down very quickly due to the lack of heat in the atmosphere. However, when a frost is expected and there are clouds and a slight wind, the clouds act as a buffer and slow the loss of heat in the atmosphere.
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How do you prevent frost damage in the home garden?
Preventing frost damage in the garden can sometimes prove to be a little tricky, but there are some easy ways to keep yourself prepared!

Always pay attention to the forecast! The Bureau of Meteorology (BOM) website has a lot of great information which can provide the home gardener with current weather forecasts which are relevant to the Australian climate. 
Cover up! Covering tender plants such as young seedlings, annual flowers, vegetables and herbs can prevent their foliage from being burnt in the peak of a frost. Cloak soft foliage and frost sensitive plants as they are more likely to be affected from heavy frosts. Drape cloths over garden-beds that are most likely to be affected. 

how to prevent frost damage on plants

Softer perennials, Hebes, being covered to prevent frost damage.

Get up, beat the sun and water! The most damage caused from a frost is when plants are still covered in ice and the sun shines on their foliage. Soft foliage plants will go translucent and can even turn black! The best prevent damage is to lightly water plants which are covered in ice before the sun hits their leaves. Shown below is a before and after photo of some oregano which was heavily affected by the frost. I watered the foliage with a hose on low pressure, the water temperature melted the ice without causing any damage to the plant. If the sun has already started to shine of affected plants it is always a good idea to still mist/water the foliage to help reduce the chances of further damage.
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Choose tough! If the area you live in an area which is known for experiencing heavy frosts try and avoid planting frost prone varieties. 

Move pots and containers! Container gardens that can be moved and re-located under under-covered areas will prevent frost from settling on the foliage. 

My plant is frost burnt, what do I do to fix it? Knowing when to prune?
When a plant is damaged by frost there is usually two main symptoms. The first symptom is the most obvious, affected plants leaves turn black and begin to wilt. If the foliage is black and the main stems are still green, cut the plant back to the healthy green stems. If left un-pruned plants are at risk from rot, fungal diseases and stem die back. Once cut back, if in a pot, move to a frost protected position. Otherwise if the plant is in a garden-bed make sure to cover the plant if another frost is expected. But in most situations when the leaves turn jet-black, especially annual flowers and vegetables, it is not uncommon for the plant to eventually die.

The second symptom is more common on perennial plants with thick robust foliage, such as Ficus and Syzygiums. Affected plants will have their foliage will turn brown/copper. Pictured below is a Metrosideros bush which was burnt by the recent frost. In this case I wouldn’t prune the affected foliage until the end of winter. The reason being, the affected foliage will act as a buffer for any future frosts and will protect the healthy leaves which are hidden below.
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As you can see in the second photo there is plenty of healthy leaves below the damaged foliage. This Metrosideros will make a complete recovery once pruned in the spring!
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The last symptom is translucent foliage. These symptoms can be instantaneous or it can take a number of days until the symptoms appear. Affected plants also start to wilt and it is best to avoid pruning until the final frosts in late winter pass. Plants that are affected are likely to recover.

I hope that this guide to beating frost can be helpful to your adventures in your garden!
Until next time happy gardening!
By Bonnie-Marie Hibbs
©BMHPhotographyTheGardener’sNotebook2017

 

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How to Prune Fruit Trees

Winter is the perfect time to prune all your deciduous fruit and ornamental trees in the garden.

Pruning your fruit trees will encourage fresh new growth to emerge in the spring, and the development of stronger branches. Pruning can also help encourage your tree to produce more fruit.

 Here is an example:

 This apricot tree was planted on the 13th of July in 2012. After 12 months you can see the substantial amount of growth that emerged over that period. The main trunk and branches are very strong, which is due to the winter prune I gave when I first planted this tree a year ago.

one years worth of growth

 When pruning your fruit trees, it is important to have your secateurs on the correct angle.

When placing your secateurs, cut parallel to the outward facing bud at the same angle as the bud, about 1cm above the bud, as shown in the photo below.

Never have the lowest point of the angle facing towards the buds tip, as this can lead to the bud rotting.

©BMHPhotography

Always cut your tree branches on an angle, just like the photo. This prevents stem die-back and allows water to run off the stems instead of sitting on top of the stem’s cut point.

Make sure that your secateurs are sharp and clean to ensure that you get a clean cut every time they are used. Unclean cuts may lead to possible infection entry points for fungus and diseases.

When pruning, prune to an outward facing bud as this will encourage future branches to develop away from the trees centre.

If you were to prune to the inward facing bud you will eventually get a branch growing through the centre of the tree, and this is what we don’t want to encourage.

©BMHPhotography

The golden rule to pruning your fruit trees is to the keep the centre of the tree free of any branches and to avoid branches from physically touching one another. By allowing the centre of the fruit trees to be open and free of branches this will help to decrease fungal and pest problems in the spring and summer.

If you are unsure of which is an inward facing or outward facing bud here is an easy way to distinguish them.

The buds themselves are like arrows, the very tip of the bud is the pointer, so the direction the bud’s tip is facing is usually the direction a new branch will form.

Here is an example:

©BMHPhotography

Here are some other examples of how I have pruned my own fruit trees, this is their second winter pruning.

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By Bonnie-Marie Hibbs

©BMHPhotographyTheGardener’sNotebook2013

Plant Health: Why do my Azaleas have brown spots on their leaves?

Have you been wondering why there are brown – grey spots on the top and underside of the Azalea leaves?©BMHPhotographyTheGardener’sNotebook2014Tetranychus urticae, commonly known as the two-spotted mite or red spider mite, is becoming a common pest in the home garden. Unfortunately, it has become a serious pest amongst many plant species, affecting a wide range of fruits, ornamental shrubs, vegetables, herbs and ornamental trees. But the main victim is Azaleas.
©BMHPhotographyTheGardener’sNotebook2014
T.urticae have strong piercing mouth parts which allow them to attack the plant’s individual cells. They produce a very fine webbing, resembling a web from a spider, on the foliage surface. Usually webbing will occur in the current feeding ‘grounds’ of affected plants. The two spotted mites are just visible to an unaided eye; usually if you look at the underside of a leaf you will see little brown/grey dots that move.

During winter months these mites will most likely congregate and feed in protected areas of a plant. For example, they will usually favour the underside of the foliage, bud/branch junctions, or even towards the base of a plant where they are protected from natural predators. As the weather gradually starts to get warmer and consistent in the spring months the mites will gradually work their way up, feeding on all areas of the plant. Unfortunately, T.urticae are more aggressive and are more damaging to a plant in the hotter weather of late spring and summer.©BMHPhotographyTheGardener’sNotebook2014Unfortunately, as T.urticae feed on their host plant, the upper leaf surface will gradually become mottled and start to discolour. In heavy infestations foliage will turn yellow and can become thin/brittle, like paper. Eventually these leaves will drop and shred from the plant.  If fruiting trees or shrubs are badly affected, it can be expected that the quality and quantity of future harvests will be poor, which is due to the weakened state of the plant.
©BMHPhotographyTheGardener’sNotebook2014
There are a few options in ways to try and maintain and control two spotted mite outbreaks in the garden. Because these mites do not like long periods of rain and moisture you can start treating your affected plants by watering them from above. But this is more effective when small outbreaks are occurring.  In the case of heavy infestations remove all the affected foliage and dispose of it in the bin (not in your compost!).  Also, consider doing a light prune, tip prune (5 – 10 cm), to encourage new growth. Otherwise another alternative is using pesticide sprays which is used to kill mites. But, depending on the state of the plant and the amount of infestation it is sometimes best to remove the whole plant and start a fresh.©BMHPhotographyTheGardener’sNotebook2014
By Bonnie-Marie Hibbs
©BMHPhotographyTheGardener’sNotebook2014

Why do my citrus leaves have a silver trail?

©BMHPhotographyTheGardener’sNotebook2015Currently there is a garden pest that is affecting many citrus trees and has a lot of people coming into my work place asking me what is wrong with their plants. Citrus leafminer, Phyllocnistis citrella, is a common pest that is currently active in the garden at this time of year when the weather isn’t very consistent. But they can also prove to be a problem in the early months of spiring, when the new season’s growth starts to emerge. The adult is a tiny moth that is silver-white in colour with yellow markings, and they have an approximant wingspan of 5mm. The adult moth lays their eggs onto the undersides of the new foliage, and once these eggs hatch that is when the symptoms and damage is most noticeable.
©BMHPhotographyTheGardener’sNotebook2015When the eggs have hatched the larvae begin to tunnel in between the fine layers of the leaf. This process usually takes the young caterpillar 5 days to do. Affected trees will show symptoms in the foliage and overall appearance. Silver aztec maze designs appear on the leaf surface and can cause the foliage to discolour overtime. Foliage can also be distorted and curled. Other symptoms can cause plants to wilt and in heavy infestations can cause affected trees to suffer from stress and remain unhealthy for long periods of time.
©BMHPhotographyTheGardener’sNotebook2015©BMHPhotographyTheGardener’sNotebook2015When the affected foliage starts to curl along the margins the larvae are fully grown. The larvae curl the sides of the leaf to create a ‘shield’ to protect itself as it goes through pupation. The pupation can take up to 3 weeks to complete and then the adult wasp emerges and the cycle repeats.©BMHPhotographyTheGardener’sNotebook2015The best method of control is to prune off all affected growth then follow up by spraying an organic pesticide such as EcoPest Oil by Multicrop or Pest Oil by Yates. Avoid using pesticides that contain toxic chemicals on your edible trees because in most cases the chemical residue can be carried into the fruit that you harvest. Citrus leafminer can be found on other plants so make sure to check over surrounding plants.

By Bonnie-Marie Hibbs

©BMHPhotographyTheGardener’sNotebook2015