1. Taxonomy and Origin
2. Morphology
3. Edaphoclimatic Requirements
4. Propagation
5. Growing techniques
6. Pests and Illnesses
6.1. Pests
6.2. Illnesses
6.3. Physiopathology


1. TAXONOMY AND ORIGIN

Its genus belongs to the family Acanthaceae, which includes around a hundred species of herbaceous, shrubby plants.

Family	Acanthaceae
Genus	Aphelandia
Species	A. squarrosa
Scientific name	Aphelandia squarrosa
Common name	Aphelandra, Zebra plant

Most varieties belong to the species Aphelandra squarrosa, although A. aurantiaca (reddish inflorescence), A. sinclairiana (pink inflorescence) and A. chamissoniana (yellow inflorescence) are also grown.

The aphelandra is native to tropical regions of the Americas and its name comes from two Greek words which mean sessile and masculine, thus making reference to the botanical characteristics of the flowers.


2. MORPHOLOGY

- Small shrubby plant, around 50cm high. Fast-growing plant, which can reach 30cm high in its first flowering period and double its size in its second year, when it can produce 4–5 shoots.
- Leaf: Medium-size, dark green, lanceolate leaves. Hard, but fragile leaves, with whitish, silver or yellow strips that highlight its main nervures. They are arranged opposite to each other in the stem.
- Inflorescences: Colour flowers, ranging from red to bright yellow. Trumpet-shaped flowers, opening from between bracts.

The most popular varieties are: «Leopoldii», wide leaves with white veins, reddish stem, yellow flowers and red bracts; «Louisae», emerald green leaves with yellow veins and golden bracts; «Brockfeld», produced in Germany, compact growth, wide, bright green leaves with yellow veins; «Fritz Prinsler», developed in Germany from «Leopoldii» and «Louisae», olive green leaves with yellowish veins and yellow flowers and bracts; «Dania», developed in Denmark from the latter, more compact, white or creamy veins, reddish stem and several yellow flowers; «Ivo», also developed from «Fritz Prinsler», dark green; «Silver Queen», lighter in colour, etc.


3. EDAPHOCLIMATIC REQUIREMENTS

- Light: It requires abundant light, but it should not be directly exposed to sunlight as sunburns may appear on the leaves. It behaves best as an indoors plant. If it is outdoors, the shade is a good alternative. During its flowering period (April-May), good light is even more important, as its light needs range between 10,000 and 30,000 lux, depending on the number of daylight hours.

- Soil/Substratum: There are several blends recommended by different authors, such as:

- Equal parts of humus, peat and sand with a pH between 5 and 6.
- ½ peat and ½ sand.
- 3 parts of peat, 2 parts of vegetal soil and 1 part of sand, adding 1.5g of the following manure per litre of mixture.
. Ammonium nitrate: 40g
. Superphosphate of lime: 37g
. Potassium sulfate: 20g
. Magnesium carbonate: 3g

- A «standard substratum» can also be used as it contributes to the good development of a wide variety of ornamental crops. It is made of:

4 parts of blond peat per each part of thin sand; if the sand is not of a good quality or is not available, it can be substituted by polyurethane or perlite. 1–3g of the following mixture can be added to the substratum, depending on the salt sensitivity of the plant:
. Superphosphate of lime: 1g
. Ammonium nitrate: 0.5g
. Calcium nitrate: 0.5g
. Potassium sulfate: 1g
. Mixture of microelements: 0.05g
. Magnesium sulfate: 0.5g
. Calcium carbonate or calcium hydroxide: necessary quantity to reach the required pH.

In case a slow-release manure is used, it will only be necessary to add the compound of calcium to increase the pH.

- Temperature: The ideal temperature is between 16 and 25ºC. It must be taken into account that, as this is a tropical plant, it does not resist frost and suffers in temperatures below 10ºC. On the other hand, if it is exposed to high temperatures, >30ºC, the leaves become smaller losing their ornamental value; besides, it is also possible that its lower leaves may fall and its inflorescences may be of a smaller size.

- Watering/Humidity: It needs high relative humidity, but no puddles should form in its soil. That is the reason why spraying is a useful method of wetting the plant. Watering can be reduced if ambient humidity is too high.


4. PROPAGATION

The aphelandra can reproduce by seed, although commercial varieties multiply by 8-10cm long terminal cuttings, with two fully developed leaves and two developing leaves. Although the process is slower, in case of shortage of mother plants, sections of stem with two leaves and sections of half of a stem with one leaf can be used, provided the stem is cut lengthways.

Mother plants are grown in individual containers on wooden boards under conditions of low luminosity to prevent the appearance of flowers. A good balance for the manure is 3:1:1 and the development of vegetative shoots will be favoured by adding most of the nitrogen as ammoniacal nitrogen.

Depending on when cuttings are obtained as well as on the size required, the number of cuttings per mother plant will be between 15 and 20.

For the cuttings to take roots, high ambient humidity is required so as to prevent the dehydratation of the leaves. This can be done through nebulization or the use of low tunnels. With background heat of 22-25ºC and ambient temperature of 20-22ºC, the rooting can occur in 15-20 days. In hot weather, these conditions make autumn and winter the most appropriate time for multiplication. Plants are usually rooted in trays in the ratio of 100 cuttings per square metre.

As regards transplanting, once cuttings have rooted, they are taken to 9cm diameter pots and two months later they are transplanted into their definitive container, whose size will depend on the number of main stems. Said definitive container can also be used from the beginning of the process for rooted and non-rooted cuttings. The size of the container should be 10 or 12cm for only one main stem and 14-16cm for 2-3 stems.


5. GROWING TECHNIQUES

- Pruning: Pruning must be done after the flowering period so as to stimulate the appearance of new shoots.
- Fertilization: It is necessary to add manure from the spring to the end of the summer. This can be done through ferti-irrigation at a total concentration of salts of 150-200ppm with a NPK balance of 3:1:2.


6. PESTS AND ILLNESSES

6.1. Pests

- Hemitarsonemus sp. produces the coiling up of the leaves. For controlling it, it is convenient to separate attacked plants from the rest.
- Plant lice produce deformations in the leaves.
- Woodlouse (Eulecanium corni) is a species difficult to combat, so it is best to prevent its appearance.

6.2. Illnesses

- Grey mould is caused by the fungus Botrytis cinerea, especially under conditions of low temperature and high relative humidity. It is convenient to carry out a general preventive control and, in particular, to control humidity through ventilation, reducing watering, etc.; it is also advisable to eliminate possible sources of inoculum. An antibotrytis product at the recommended dose should be applied.
- Stem rot is produced by the fungi Phytophthora spp. and Pythium spp.

6.3. Physiopathology

- Chlorosis is caused by the lack of manure or the excess of light.
- Leaf-drop generally occurs due to the lack of water, although it can also occur under conditions of temperature below 15ºC and excessive humidity.

On the other hand, the aphelandras are very sensitive to high temperatures and low ambient humidity, which can cause the sloping, coiling up or dropping of the leaves.

- Premature flowering is caused by excessive light, a sudden increase of lighting or high temperatures.
- Burns can be caused by direct exposure to sunlight.

Author: Infoagro