Powdery mildew of the sage

  Powdery mildew or white sickness is a cryptogamic disease, that is of fungal origin, which can affect sage plants and occurs on the leaves. This is the most frequent pathology among those that can affect this aromatic herb and occurs in particular with mild temperatures and high humidity. It is a very simple disease to identify: because the white patches that are seen on the leaves of the sage are very characteristic. A reader of Orto Da Coltivare, Barbara, asks me exactly what her plant can have, describing the symptoms of powdery mildew. I answer publicly because I think it may be useful for many to know how to defend themselves from this problem with natural methods and above all how to prevent it. Recognizing powdery mildew on sage Those who cultivate the vegetable garden will already know powdery mildew because it is a frequent pathology also on other cultivated plants, in particular on pumpkin and courgette. Powdery mildew is also called white sickness precisely because it work


The Azalea does not constitute a genre to himself but falls within the kind of Rhododendron. This genus is divided into two groups: the rhododendrons, large evergreen or deciduous shrubs, and the azaleas, evergreen dwarf shrubs, green leaves, or small and deciduous. Until a few years ago, it was mistakenly believed that there were two distinct species, but in reality, both azaleas and rhododendrons are part of a single genre, that of the Rhododendron precisely in turn is part of the family of the eraceous. They have an average size, reach 40-90 cm in height; The subtle drums, semi-new ones, are densely branched, and give rise to rounded or elongated shrubs; The leaves are oval, dark green, rough and slightly huge; In spring, before snack the leaves, produce numerous flowers in trumpet, gathered in bunches, to the apex of the branches, rosé, red or white; There are numerous cultivars and hybrids, and in the last few years on the market there are also azaleas of lilac or azure. Evergreen varieties fear the cold slightly, they are cultivated as flat plants; The Caduca or Semisempreverdi leaf varieties are instead cultivated in the garden.

Azalea cultivation

The azaleas belong to the Rhododendron genre. The botanists have in recent years unified the species realizing the fact that there are no substantial differences.

Some distinguish the two kinds by counting the number of stamens or relying on the difference between Caduca or persistent leaf plants.

Others, instead, point out that the azaleas have more pointed leaves and with small hairs while, observing those of the rhododendrons, with a magnifying glass, small scales can be noted.

In this article we will take care of the general conditions of cultivation, which are adapted to both genres, we will have a particular eye for the cultivation of these potted plants.

Azalea temperatures


Generally, the Azaleas love to be cultivated in a temperate climate. They certainly do not suffer damage if it goes from -10 ° C to 20 ° C in our area. However, it is possible to buy even more resistant varieties due to research and hybridization in recent years. If lower temperatures are reached in winter it is good to pick up the plant in a cold greenhouse or, if it were not possible, close it to a south wall that protects it at least by strong winds. It can also help put the insulating material around the vessel and cover the aerial part with a special sheet. It is good to place it in the shade of great hardwood or conifers in summer, always maintaining high environmental humidity, much more important than that of the ground. For the plants in full earth, it is always worth the advice to choose the exposure well. The more we live in a warm climate and more it will be indispensable to prefer a shady and fresh area.

Azalea land


The substrate is certainly the element that is more important to cultivate these plants successfully. The eractions in fact needed tendentially acid terrain, with an optimal pH that is around 5 / 5.5. A pH too high inhibits the absorption of nutrients and is the most frequent cause of chlorosis, which manifests itself with the yellowing of the leaves. These plants require quite rich soil of organic substances, well-drained and without water stagnation, and should not be planted too deeply, given that they have very superficial radical apparatus. They can also be cultivated in a vase, remembering the greater demand for watering plants in vase compared to those placed in the ground. Azaleas are acidophile plants. They, therefore, need at least subacidal soil (the ideal is pH 5, 5-6).

The ideal terrain is therefore what you can find under conifers. To cultivate them in the pot you can then recover from our garden a bit of this soil or buy it in suitable. We must avoid prepared with a high percentage of peat. Rather it is better to choose a generic soil and mix the needles, pine bark and possibly the draining material (ideal is the volcanic pumice or maximum perlite).

To keep the soil fresh and avoid the change of the pH you can on the surface also predispose a good insulating layer always with the bark and pine needles. The radical apparatus does not develop deeply and then they will need wider than high vases. At the bottom, you must always prepare a great draining layer of at least two centimetres. It can be composed of pumice or expanded clay we avoid the gravel that could release calcium carbonate. Let us always make sure that the drain holes are free. Both in the full land and in the pot it is ideal to place the azalea in a slightly raised position compared to the level of the ground, creating a mound. This will avoid the stagnation of the water right where the plant is more delicate, that is in the area of ​​the collar. However, it will lead to at least until the plant has been stabilized, more frequent irrigation interveners.

Azalea exposure


In areas with a climate that tends to be mild the azaleas place themselves in a sunny place; In areas with hot summers, it is instead advisable to place the azaleas in a semi-mobilised or shaded place. Garden varieties do not fear the cold, even in very cold temperatures. Shadow is undoubtedly preferable. We can evaluate different exposures if we live in alpine or pre-alpine areas. Here you are particularly helped by lower temperatures, frequent rains and naturally higher atmospheric humidity. This does not mean that some varieties, especially deciduous, especially love exposure in full sun and it will help them to flour sharply: the corollas, however, will last less. However, they are specific characteristics of cultivar and to know it cannot be experienced. If the plant is in a vase it is certainly worth it (especially if we live in a fresh area) to try various exposures before deciding the final one.

Watering azalea


From March to October, water the azalea with regularity, though to soak the ground; During the winter months watering sparingly, only in the event of prolonged periods of drought; Evergreen azaleas need to be watered all year round, keeping the ground slightly wet.

fertilization is very important for the healthy and regular growth of the plant. After the cultivation, the plant will be periodically fertilized with specific products for acidophilic plants; The yellowing of the leaves, due to chlorosis, is hindered by periodically providing a soil conditioner based on iron chelates. Azaleas don’t like having constantly wet roots. This can cause rot and poor growth.

It is necessary to intervene more frequently after the resonances or after the residence but to ensure that the substrate is always slightly humid, but absolutely without excesses.

It is much better to irrigate once in an abundant way, and then wait for the substrate to be completely dry that distribute water constantly and without criterion.

If the days are particularly warm and dry instead it is very useful to vaporize several times the leaves and (if we keep the plant on a paved) wet the surrounding area so that the water gradually evaporates. Excellent is to rest the plant on a boot full of water and gravel, without this coming to the roots. It can also be useful to put around other broadleaf plants that with their breathability help to maintain a good environment for azalea.

We remind you that, since it is plants in general, calcifuges, it is better for irrigation and vaporizations to use demineralized water (like the one for ironing irons). You can possibly collect and use rainwater.

Some advices


To always have beautiful azaleas to envy the neighbour we give you small tips. Always remove the flowers at the end of the flowering carefully removing the flower peduncle: this will avoid the plant spends energy for seed generations. Fertilize at least twice a month with iron sequestrate: the latter will help the absorption of nutrients with an obvious reduction of leaves. Finally, remember that these plants particularly affect the irrigations during the hottest hours of the day, so it is good to bathe them early in the morning or at night.

Azalea fertilization

To have beautiful blooms it is good to intervene with specific fertilizers for acidophile plants. Both slight granular ones are good and liquid ones. A great opportunity, to be combined with vaporizations, are also foliar fertilizers. We must still administer very light doses because these plants naturally live in rather poor soils and do not particularly like to be stimulated. We concise in general from February to mid-July, but let’s not a pushover. Our intervention could encourage vegetative growth and new branches, still herbaceous, could be irreparably damaged by winter frost.

Azalea pruning


Especially for vessel specimens, it is necessary to intervene with periodic pruning of the Azalea to stimulate its growth, maintain the shape and prevent them from becoming too large. The ideal is to intervene immediately after flowering. Intervention too late in fact you can interfere with the issue of the branches that will bring flowers the following year. It is good to cut external branches more and try to shed light inside the plant. Those crooked or damaged, on the other hand, can be eliminated at any time.

Loss of the leaves

As we said there are deciduous azaleas and evergreen azaleas. The first usually lose leaves from the end of summer. What is certain is that they lose them first if they live in a dry environment.

Even the evergreen but lose the leaves. They do it in autumn and in spring, but these have already been replaced by others raised in summer and at the end of winter. If the leaves become brown in the summer it is the signal that our azalea has a problem. Generally, it is too many or few irrigations grounds not suitable or excessive fertilization.



Chlorosis of the leaves can be caused by various factors, but usually, at the base, there is too heavy soil and an abundance of calcium carbonate. As always, the ideal is to avoid irrigating plants with hard water and do not use concrete vessels. To remedy it is necessary to mix the irrigation water of the iron sulfate. This lowers the pH of the soil making the iron again soluble. If it should not be enough you can administer the chelated iron both by irrigation and foliage fertilizer. It will be useful to intervene as soon as possible by focusing the plant and replacing the substrate with one more suitable and avoiding repeating errors.

Azaleas life

These are very longeval plants. If dealt with in the right way they can live even more than 100 years. This is why they are also widely used for the production of bonsai.


Unfortunately, it is not possible to give a precise indication of their flowering period. There are many varieties, cultivars and hybrids and can flourish from the beginning of March to late October, even depending on the climate in which we live. The advice is, if we have specific needs, to contact specialized retailers who can direct us towards a specimen that encounters our needs for size, flowering, resistance and colour of the buds.

How to treat the azaleas of the florists


Most of the azaleas we have in a jar home derive from purchases at florists. In fact, excellent vessel plants are considered that they are quite simple to force and, as well as having a great visual impact, can be available all year round. What is really difficult but is to be able to survive them and return to blooming the following years.

First of all, it would be important to be able to identify it to understand if it is or not a rustic specimen. As soon as you arrive at home it is important to remove the paper that wraps it and, if the ground was dry, irrigate it abundantly. A great method consists of inserting it in a bowl full of water and wait for more air bubbles to be produced. At that point, you can withdraw and let you drain long. This operation must be carried out once a week. However, each time the soil must not remain damp for more than two hours. It will then be necessary to put it in the coolest area of ​​the house, possibly where there is high environmental humidity. The bathroom could be a good solution provided that it is not too hot. In winter it can be moved to a non-heated room. Generally, also 5 or 6 ° C are not a problem. From spring to autumn it is fertilized monthly with a low-nitrogen and high phosphor-high product. This stimulates the rooting and production of buds. Instead, excessive vegetative growth of leaves and branches must be avoided. It is necessary every approximately 6 months to check the roots extracting the ground bread: if we see that they are many and tangled on the bottom, cutting them should be taken. The plant will then have to be inserted into a slightly larger vessel than the previous one.

Variety of azalea

The name Azalea is rather generic and within this label, the real enthusiasts of these acidophilic plants know all the main varieties. The first difference is made between the azaleas of the apartment and garden azaleas. A furthermore precise difference can then be made between the different varieties and cultivars of Azalea.

The Azalea Mollis is a type of azalea much appreciated because of its intense colours ranging from yellow to red to rose crossing all the shades of this colour. The Mollis have large-shaped fun flowers but do not give a particularly fragrant flowering. One of the most interesting aspects of Azalea Mollis and its flowers is the fact that this plant flowers when the leaves are not yet present and therefore the effect of colour is particularly intense.

Le Azaleas of Jinfo Mountain


For the lovers of gardening more travellers, here is a place where azaleas are a corollary to a seen and a unique, so particular to be identified as a UNESCO World Heritage.

We are in China and more precisely on Jinfo Mountain, or Jinfo Shan, a mountain of 2238 meters of altitude representing the highest peak of the Dalou mountains in the Chongqing district. This summit, from the name that means “mountain of the golden Buddha”, in addition to offering incredibly beautiful views, is also an area in which the azaleas are diffused. In fact, between April and May, when these plants bloom, the mountain fills with pink, white and red patches, creating an incredible chromatic effect.

Azalea in winter

Azalea is a plant that tolerates the cold winter climate of most areas of our country, including the main cities of northern Italy and the Po Valley. On the more cold reliefs and valleys, winter frost and especially late frosts can cause serious survival problems at Azalea.

In these areas therefore it will be appropriate to cover the azalea plants with the cloth during the coldest periods of the year.

In addition to this trick, it will be necessary to remember to give a little to drink at the evergreen azaleas even in winter, obviously taking care to do so far from the less cold periods of winter to avoid damage to plants due to the ice cream. In fact, the evergreen plants maintain a minimum of vegetative activity even during the winter period and in the absence of rains, when the ground becomes too dry, there may be serious plants to plants planted outdoors.

Azalee at home


The cultivation of azaleas at home must take into account the factors that diversify the domestic environment from the external one or the difference in temperature, the difference in humidity and the difference in light.

In the apartment and at home, the temperature is more constant than outside and in winter it is certainly more suitable for the vegetation of azaleas. However, care must be taken not to expose homegrown azaleas to excessive temperature changes or too cold currents. Before taking the azalea outside you will then have to check that the temperature changes are not too accentuated to avoid dangerous frosts, as well as in choosing the position of the plants inside our house you will have to be careful not to keep the azaleas in too much zone. exposed to cold drafts or too close to doors and windows that face outwards and which are often open to ventilate the premises.

The light is another very important aspect to take into consideration and in particular, in this regard, you will have to place the azalea plant in a place with sufficient lighting, so close to a light source such as a glass door or a window.

As for the humidity finally, at home, the climate tends to always be very dry and you will have to be very careful not to send the plant into water stress conditions, checking the moisture of the ground from time to time and possibly providing with The waterings.

You may be interested to read about the how to grow mint in pots blogpost/ cheese bread recipe/ corn cake recipe/ Corn flour pastel recipe/ tapioca pizza recipe/ baked cream pastel recipe/ bis pave recipe.


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