When Should Pot Grown Azaleas Be Given Sequestrene

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fl large scalc, some 70,000 seedlings being raised. Many different species and hybrids were used, so the plants in this group vary very considerably in growth, including low, medium and tall, upright or spreading.

Flowers are usually single, up to 4'/j in (11.5 cm) across, but when pot-grown will usually be less than this. There were a few semi-double and double-flowered varieties.

Flowering Pot Plants

The four groups described provide the grower with a wide range of colour and plants, but in addition there are many other azaleas which do not fall into these groups.

As already mentioned very many nurserymen were engaged in raising new hybrids, and quite often were successful in producing notable plants. It was quite a common practice for these to be known by the raiser's name. Such a man was Aan Vuyk, who in the early 1920s succeeded in breeding some beautiful hybrids. Many of his plants were named after famous musicians, such as 'Beethoven', but two of the most attractive were named after the raiser, namely 'Vuyk's Rosy Red' and 'Vuyk's Scarlet'. Both these make excellent pot plants as they are bushy, very slow-growing and have beautiful big flowers.

Another variety raised in Holland in a similar way, but without the knowledge of the raiser's name, is 'Sakata Red', which is also an asset to any collection.

When dealing with such a large class of plants as the evergreen azaleas, it is quite impossible neatly to place all the known hybrids into well-defined groups such as those described. Ii is quite likely that you will, from time to time, encounter plants such as 'Sakata Red' which are well worth growing, and you would require a very large greenhouse indeed to grow all the beautiful ungrouped azaleas which are available throughout the world.


The only way to start a satisfactory collection of azaleas is to buy young plants, which will usually be two or three years old except in the case of very small Belgian Indian azaleas. As azaleas can be lifted and potted at any time in the year, it is not necessary to purchase them at any specific time, but from your own point of view, it is more expedient to purchase your plant in the spring. By doing this the plant is settled in its pot and under your control at the time when it is making new growth and developing its llower buds for the following season.

It is crucial that the plant is given the cultural attention it requires during the late spring and the summer, for a successful show of bloom the following winter or spring.

Azalea'Vuyk's Rosy Red'. The large brighlly-co loured flowers of (his type of azalea »re always greatly admired.

However, assuming thai you purchase a plant in bud during the winter to spring period it will, in the case oi' all varieties other than the Belgian Indian, require polling. For this purpose you can use either a plastic or a clay pot, whichever you prefer, but the important point is to use the smallest possible pot which will satisfactorily contain the roots. The reason tor this is thai azaleas are capable of living for very long periods of time, and by starting with the smallest size of pot you are increasing the length of time the plum can serve as a pot plum. All flowering pot plants benefit by being potted on into a larger size and this is particularly true of azaleas.

Bv starling with a small pot you increase the number of times ii can be potted on. Ultimately it will require a larger pot than is practicable in order to continue growing satisfactorily, but by this time you wilt have enjoyed some 15-20 seasons of flowering. Azaleas are such permanent plums that you cannot help but gel attached to them. I have a Kurume azalea called 'I lino-mayo' which I acquired about fourteen years ago, and it has become a rather special favourite with me. I usually force it into bloom in late winter and in some years it is completely covered with flowers. A suitable compost for azaleas consists of:

1 standard seed tray of peat 1 standard seed tray of leafmould

1 standard seed tray of sand

3 oz (85 g) hoof and horn meal

Leafmould is difficult, if not impossible, to obtain nowadays, and if it is not available use lime-free soil.

Pot the plant firmly and then water by filling the pot up to the rim. It' the plant has been potted correctly the level of the compost will be about V« -1 in (2-2.5 cm) below the level of the rim.

The Indian Aulea is one of the be« winter-ftowermg pot plants

The azalea should not require watering again for at least a week, assuming that it has been put in a cool greenhouse immediately after potting.

Azaleas thrive in a moist compost and should never be allowed to dry out. On the other hand no pot plant will survive a wet compost, such as the condition which exists when the pot is left standing in water lor a period of time, it is necessary to strike a happy medium and in this respect you often can, in the case of azaleas, receive help from the plant itself, because the main stem turns a darker colour when the roots are well supplied with water. When the moisture content of the plant is ideal, the dark colouration of the stem ceases about I in (2.5 cm) above the soil level. When it is higher than this the compost is on the damp side, and when it is lower than 1 in, the plant should be examined daily until it has been watered. On some plants it is very easy to see the dark colouration, but not all plants give a clear indication; therefore you have to be careful, and if you cannot distinguish any difference in the colour of the stem do not jump to the conclusion that the plant is short of water. Use this guide in conjunction with the feel of the compost. If it feels moist, it obviously does not need watering whether you sec a water line or not.

You should not expect good results from your plant as soon as it has been potted, as it needs to become established as a pot plant and to have grown in the right conditions for a season.

Even in the case of Belgian Indian azaleas you often find that the plant has suffered while on display waiting to be sold, and as they are invariably potted in a soilless compost it is not unusual for this to have become too dry. If this should prove to be the case the plant should be placed in a bucket or bowl of water so that the pot is almost immersed, to ensure that the compost receives a thorough soaking, and then it should be allowed to drain.

When the azalea has finished flowering it should be kept in a cool place where the atmosphere has a good moisture content, such as a cool greenhouse or a spare room in the house which is unhealed or only partially heated. A temperature of 40 - 50°F (5 - 10°C) is ideal and will make the plant grow steadily assuming that the light is sufficient. Plants should not be kept in the living room or cent rally-heated rooms for longer than the period they are in (lower, usually some four weeks, as the atmosphere is too dry, and although they will stand limited exposure to these conditions a prolonged stay could damage a plant to the extent that it would take a long time to recover.

Although it is possible to grow azaleas in pots without a greenhouse it is, of course, far more satisfactory to grow ihem in a greenhouse, particularly if you have a collection of different varieties.

All varieties ui azalea, except the Belgian Indian, should be removed from the greenhouse in spring and put in a sheltered spot where there is some protection from the frost. The Belgian Indian hybrids are not frost-hardy, consequently they need more protection than the other groups, and should be kept in the greenhouse until late spring when they can be removed to the protection of a frame or similar place.

All pot-grown azaleas should be bedded out in the summer and it is easier and quite satisfactory to keep the plants in their pots rather than planting them in the ground. The best site is one which is open to the sun for some three or four hours a day, preferably in the morning, and for the rest of the day in partial shade. It is not essential because azaleas will endure partial shade all the time or even full sun all the time, but in the case of azaleas in pots it is desirable for growth to be as dense and compact as possible. Partial shade all the lime encourages taller and more open growth. Full sun all the time causes the pots to dry out far too quickly, and would necessitate watering too frequently.

Belgian Indian azaleas should not be bedded out until all risk of frost has passed.

The object of bedding out azaleas in the summer is to give them natural growing conditions which ensures that good strong healthy plants are developed. A good method to use is to dig a hole large enough easily to accommodate the size of pot involved, then place some peat at the bottom of the hole; stand the pot on this and then surround the pot with peat. The soil is then packed round the peat and made very firm to ensure that the pot is secure against the wind. The pot should be so placed that the ground level is about 1 in (2.5 cm) below the rim of the pot.

The use of peat as a lining round the pot is to prevent it coming into contact with the soil which may not be lime-free, also damp peat will retain the moisture better and reduce the amount of watering required particularly where clay pots are involved.

All the azaleas should have been bedded out by early summer and this is a good time to give them an application of sequestrene (active ingredient iron chelate) which will suffice for the whole season.

A lot has been written about using rainwater for the watering of pot plants, particularly plants which require acid soils, and it is very good when you can do this. On the other hand, if you grow a large number of pot plants it is not always possible to collect enough water to meet their requirements. In my long experience tap water (unless it is 'hard') is just as satisfactory and 1 have never used any other source of supply, so do not worry if you have to use tap water for your azaleas, as they will not come to any harm, particularly if you give them the sequestrene treatment once a year.

The azaleas should be left bedded out until the end of the summer, when they should be lifted and put in a frost-free place. During early autumn they can be kept outside if given the protection of glass or a polythene cover, but by late autumn they should be inside the greenhouse. At this stage it is better if the greenhouse is unhealed and the thermostat is set for say 36°F (2°c), ¡ust enough to keep out the frost. This ensures that the azaleas are growing in cool conditions, which is absolutely essential if they are to flower satisfactorily.

It is necessary for the plants to have a 'chilling* period i.e. below 50°F(10°C) for four to eight weeks, as it is during this period that processes occur which prepare the buds for flowering and, as a result, the buds all break into flower at the same time, as soon as a period of higher temperature is experienced. Without this period of'chilling*, flowering is often spasmodic over a long period of time and the azalea fails to give a good show of bloom.

When I first started growing azaleas in pots, this spasmodic blooming often occurred with my plants. I read somewhere thai it was due to overwatering, so I began to water my plants very carefully, but of course it did not give the desired results.

It is often recommended that azalea plants should be sprayed daily with cold water, and no doubt this practice developed because spraying in autumn would result in chilling the plants, particularly on overcast days when the plants would remain damp for a few hours, if not all day. It is not however necessary to spray plants at all if the temperature is kept low by avoiding artificial heat and opening the vents on sunny days.

After the plants have been subjected to this 'chilling' period they are ready for forcing into flower, and this can commence at the beginning of winter or in late autumn if the weather has been cold enough during the early autumn. All that is necessary is to put the plant in an average temperature of65°F (18°C), in a position where it is receiving good light. All plants need light, which provides the energy for growth, and as the object is to speed up the process of flowering obviously the plant must have good light as well as heat.

Ideally the plant should be put in a propagator which is healed to a steady 65°F (I8QC). If this propagator is in the greenhouse the natural light will no doubt be sufficient to sustain growth. It is better, however, if you can provide the plant with artificial light, because there arc many days in winter when the light intensity is insufficient to sustain growth. A 'warm white' fluorescent tube about 12 in (30 cm) above the plant for 12 hours per day, say 8 am to 8 pm, will make a considerable difference to the length of time required to bring the plant into full bloom. It is not essential to provide artificial light, nor indeed to have a propagator. The plant can be forced by placing it in a centrally-heated living room, in the window, or in any position where it will receive maximum light.

It is, however, desirable if you have a collection of azaleas, and wish to maintain a continuity of bloom, to be able to control the rate of forcing, and this can best be done if you can control the heating and lighting conditions.

Very few flowering plants will thrive inside the house because the air, particularly in centrally-heated rooms, is too dry. Azaleas are no exception, and five or six weeks in the house will begin to affect the plant. It will usually show this by shedding some leaves. This is another reason in favour of using a propagator, because the atmosphere can be kept moist.

On the subject of leaf shedding, it should be mentioned that although the azaleas with which we are concerned are called evergreen azaleas they are not evergreen in the true sense of the word. They do in fact appear to be evergreen because they grow two types of leaves. One type grows in the spring and the other in the summer. In the autumn they shed most of their spring leaves, and it is important to realise this; otherwise you might conclude that the plants are not happy when the leaves begin to die and fall off. It is a natural process and does not indicate that the plants need watering or a change of environment. On the other hand, by the time the plant has flowered all the spring-grown leaves have long gone, and a fall of leaves at this time would be of the summer leaves and indicates that the plant is in need of attention. The summer leaves are more permanent than the spring leaves and usually last until the following year, and in some species even longer.

In a temperature of 60-7G°F (15-2TC) with good light, it takes about four to five weeks for the tight buds to open into flower. With a carefully-selected collection of azaleas you can start with the first plant in late autumn, and as soon as this is in bloom and ready to move into the house, the forcing of the next one is commenced, and so on until late spring, by which time it is unnecessary to force the plants.

The plant remains in bloom about the same length of time as it takes to force into bloom; consequently, when it begins to fade, the next plant is ready, and so a continuity is achieved.

Azaleas are possibly one of the most satisfying pot plants you can grow, because once you have started a collection you are never without flowering pot plants during the winter months.

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  • cayden moore
    When should pot grown azaleas be given sequestrene?
    7 years ago

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