CARING FOR LAVENDER

I wonder how many gardeners have gleefully planted lavender with the aim of filling their gardens with the magnificent fragrance of these grey foliaged charmers, only to find them die out in a very short time. I think also that there have been a few commercial growers whose motivation was more towards monetary gain and they have experienced the same dreaded result.

The fact is that lavenders are of Mediterranean origin where the soils and climate are so vastly different to that of Queensland. Here we have hot wet summers, whereas in their natural habitat the summers are still quite hot but they have very little summer rain. As a result the lavender plants in the temperate region spend the summer with dry soil surrounding their roots and, because of the dry heat, the pressure for humidity loving fungal diseases is relatively low.

Obviously we can’t recreate a Mediterranean climate here in Queensland so if we are to be successful in growing lavender we have to firstly choose the appropriate variety and, secondly, work a lot harder to keep our lavender plants alive.

For many years the most successful lavender variety for Queensland gardens was the French lavender, Lavandula dentata. There were a few skilful gardeners who managed to keep the Italian lavender alive as well but when it came to cultivating the other European varieties it was a well nigh impossible task.

Some years ago a variety of lavender was bred in New South Wales, apparently using Lavandula pinnata as one of the parents. This hybrid was touted as being suitable for warmer climates and sold as Lavender “Sidonie”, the Australian lavender. It has a greenish coloured flower and, although living up to its reputation as being pretty hardy in our climate, I have been terribly disappointed with its lack of fragrance.

There is no doubt that the hybridisers of lavender have been flat out and the large number of new cultivars that have hit the market over the last few years has confirmed this. We have had a couple of hybrids, the names of which have since been forgotten, in our garden and they have literally thrived on neglect. They are a shorter grower than the species lavenders and are a little more open in their growth habit and this, I think, has contributed to their disease resistance and longevity.

Recent releases which promise to be as hardy as the ones in our garden are Lavender Lace, the bracts of which deepen in colour as they age; Violet Lace with deep purple flowers to contrast against the grey green foliage and Winter Lace, which simply denotes  its flowering season.

If we are to achieve reasonable success with lavender we need to provide as near to ideal conditions as possible. As I mentioned earlier, they are not accustomed to wet summers and as result do not take kindly to standing around in warm wet soils. To compensate for this, lavender should be planted in soils that are completely free draining and if these can’t be provided, either raise the bed or plant them in containers filled with a premium grade potting mix.

The soils in their native land are usually alkaline by nature so that means applying dolomite so as to bring the soil pH up to between pH 7.0 and 7.5. A pH test kit will help determine how much dolomite should be applied and how often.

The summer is a particularly trying time for lavender as this is when fungal disease is most likely to attack, even to the point of being fatal. Cutting the plants back by about a third at the beginning of summer and dusting them with dolomite will help minimise the risk of disease. An application of a complete organic fertiliser in spring and autumn will help as will periodic applications of superphosphate and sulphate of potash.

A sprig or two of lavender in the car and the office will help to make the trip to and from work and the day in office more peaceful thanks to the calming effect of the fragrance of lavender. What better reason to grow some?
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COLOUR IS IMPORTANT

 

Colour is not just important in the garden, it is also important in our everyday life and for those who are enthralled by the colour wheel and all that it means, there are countless books available on the subject. I’m not sure that I completely agree with Nori and Sandra Pope who wrote in their book “Planting with Colour” that 10% of men are colour blind and that women store visual images in both sides of their brain whereas men store them in only one side! They then rationalise that women, therefore, see colour in a different way to men and that men do not have the selective capacity of a women when it comes to colour.

On reflection though, I really think that, as a general rule, women are better at working out colour schemes in the home as well as in the garden than most of us mere males. Despite this, I’m going to attempt to impress you all by writing what I hope will be an authoritative on two of the foliage colours which I think are just great in any garden – pink and red.

Red is one of those colours that shouts out at you and, if used to extremes, can overpower the garden visitor, whereas pink is more subtle and relaxing. It has been said that pink is the sweeter side of red and although red is the colour of passion, pink is more romantic and charming.

When used in the garden these two colours combine in a very special way and can work wonders in creating interest and excitement, especially when the colours are provided by foliage.

Although most gardeners, when discussing the vibrant colours of the poinsettia, usually refer to the flowers, the vibrant reds and pinks are those of the leaf bracts that surround the rather insignificant flowers. For winter and spring colour you simply can’t go past the humble poinsettia.

For longer term colour you need to look at plants that carry the colour in their leaves all year round. I remember wandering through a garden one day and came across an avenue of trees. My eye was attracted to a bright red plant at the end of the avenue and in the sunlight it looked as if it was on fire. Of course that was what it was meant to do because the gardener knew that a bright red plant had the ability to draw one’s gaze in much the same way as a statue. In this case the plant in question was a red iresene and these will do a brilliant job of brightening up an area under trees and taller shrubs.

Other plants that provide splashes of red are the crotons and of course the cordylines and dracaenas. Most of these are best in part shade, although they will tolerate a little bit of sun, but too much sun can fade the colour.

One of the common problems with crotons is that they have a tendency to drop leaves for no apparent reason. This is usually at the change of season so it is considered to be a climatically induced problem for which there seems to be no answer. Cutting the plant back by about one third and applying a high nitrogen fertiliser seems to be all that’s needed to bring the plant back to its former glory. An organic lawn fertiliser, such as Eco 88 or Grassmaster, is ideal for these plants.

The acalyphas are another species that can provide splashes of red and these are plants that are capable of being grown out in full sun. The larger leaved Acalypha wilkesiana has been a favourite for many years and it is as tough as can be. It does need to be regularly trimmed. It is also the preferred food of grasshoppers and caterpillars but they will rarely do enough damage to cause major problems.

When it comes to pink plants one that immediately springs to my mind is one that
performs so well in our own garden. This is the Loropetalum chinense, sold under the trade name of China Pink. There is another sold as Razzleberri and both will do so well with a minimum of care and attention. As well as the deep pink, almost red, foliage it is covered with multiple flushes of pale pink flowers.

Of course whenever discussing pink foliage we should never ignore the contribution that many of our rainforest and other native species can make. The lovely pink flushes of growth from the syzygiums and acmenas are well known. They are most attractive and should always be a part of the pink and red garden. Some of the callistemons also produce flushes of pinkish coloured growth as well as the flowers.
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ROSE CARE

The climbing Albertine rose is certainly a beautiful rose to have in the garden but there is a down side and that is the vicious thorns which are in abundance. As with all roses, to get the best results they need to be pruned.  If you have just pruned your Albertine rose I’m sorry to say that you have done it at the wrong time and the chance of getting a prolific flowering is almost nil.

The climbing roses that have only a single spring flowering should be pruned as soon as the flowering flush is over, not during winter as is the case with most other roses.

All the shrub type roses that were pruned during winter will be making lots of new growth now which means that the dreaded black spot disease will also be making an appearance.  Whenever I visit gardens in the colder regions of Australia I become intensely jealous when I see roses without a trace of black spot on the leaves. Gardeners in South Australia for example, where they experience hot dry summers and very low humidity levels, don’t find it necessary to constantly wage war on the dreaded disease.

The warmth and humidity of the tropics and subtropics is an ideal environment for the proliferation of diseases such as black spot and this makes rose growing a much more onerous task in this climate. 

Black spot manifests itself as a small black spot surrounded by a yellow halo appearing on the leaves. Before long a large area of the leaf yellows and in no time at all the leaf drops to the ground. If left untreated, the fungal spores that exist on the affected leaves will multiply and be rapidly spread by a number of different vectors, such as wind, birds and insects, to other previously unaffected foliage.

Controlling black spot requires a concerted effort on the gardener’s part and garden hygiene is the first step. Gather up all the affected leaves from the ground on a daily basis and put them into a plastic bag, the top of which is tied tightly to prevent the spores from escaping. Once this is done leave the bag on a path in the hot sun to “cook” the affected leaves before consigning to the garbage bin. Under no circumstances should diseased leaves be placed in the compost as this will only help to spread the disease even more.

Nutrition is another important aspect of black spot control - the healthier the rose bush, the less damage will occur from pests or disease. The element potassium plays a significant role in building disease resistance, so make sure the rose fertiliser you use has a high proportion of potassium. There are two types of potassium commonly used in fertilisers - potassium chloride and potassium sulphate. Roses are particularly sensitive to chloride so it is important to choose a rose fertiliser with the potassium in the sulphate form, and if the other nutrients are in an organic form, so much the better. Apply the fertiliser every six weeks from August right through to March.

To strengthen the disease resistance factor even more, supplementary dressings of sulphate of potash should also be made every three months, at the rate of 150 grams per bush.

Even with this nutritional regime it will still be necessary to spray the roses with some kind of fungicide at regular fortnightly intervals. The first I would use is the chemical fungicide Triforine, because of its undoubted prowess in the control of black spot. If, however, you are organic you can spray with one of the copper based fungicides.

The next spray in the armoury is a mixture of one dessertspoon of bicarbonate of soda in ten litres of water to which has been added a few drops of dishwashing liquid and a few drops of seaweed extract.

Alternate between these various fungicide treatments at fortnightly intervals for best results.

It has also been found to be beneficial to use, on a regular basis, some of the preparations that contain mixtures of seaweed, fulvic acid and plant substances such as bluish dogbane, poplar and cypress extracts. These are commonly sold under the name of Plant Care or Plant of Health Spray. Gardeners who have used these products over a prolonged period report a much reduced incidence of all disease and pest attacks, so much so that pesticide spraying has been almost eliminated. This is a worthwhile alternative

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WHAT TO DO

Prune back Australian native plants by one third as soon as they have finished flowering. Some gardeners are reluctant to prune back very young plants but it’s a case where you have to be cruel to be kind.

If leaves of capsicums or tomatoes are being skeletonised look out for the 28 spotted ladybird. This is easily distinguished from the good ladybird which only has a few spots. Spray with Mavrik, or similar, or pick each one off by hand.

Keep a close eye on the new growth of roses for signs of aphids and if present spray with a low toxicity insecticide.
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Apply sulphate of potash to cordylines at the rate of 100 grams per plant to intensify the colour of foliage.

Beetroot seeds or seedlings can go in from now on. Because beetroot demand a high soil pH, the beds should have had some dolomite applied about six weeks ago. If this hasn’t been done, treat the soil with a product sold as 4 Vital at the time of planting.

Inspect the lower leaves of sugar snap peas on a regular basis for the grey ashlike symptoms of powdery mildew and at the first sign spray with a mixture of 10% full cream milk to 90% water.
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If you had chrysanthemums in flower for Mother’s Day, you should be able to lift  and divide now.
Water melons, zucchinis and pumpkins can be planted at this time so they become established before the hot weather.

If you can water your lawn, or if it looks like rain, get out and apply a complete organic fertiliser to get it moving again for summer.
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If you have a compost heap, it’s a good idea to turn it and use any of the well rotted material for mulch.

Keep the water up to newly planted fruit trees and mulch well, but keep the mulch well away from the trunk.

Shrubs planted in June or July should be settled in well now, especially after the rain, so they can be lightly fertilised with a complete organic fertiliser.