Asclepias tuberosa Red King®

The interest fort he cultivar Asclepias has been there for years. Because of the introduction of new colours and a longer vase life the interest in the market is rising. Green Works is introducing the Asclepias tuberosa Red King®, this breed is distinguished by:

  • High production
  • Long flowerstems
  • Good quality during cultivation
  • High ornamental value in the trade and consumer phase
  • Good shelf life of the leaves and flower
  • 3 harvests per year (depending on climate)
  • Low labor required

After several years of extensive testing in field conditions where the commercial value of the end product has also been taken into account, Green Works is introducing the Asclepias tuberosa Red King® to the market.

In addition to the cultivation optimization Green Works gives a lot of attention to the quality of the young plants. The Asclepias tuberosa Red King® is propagated through tissue culture. This guaranties a healthy batches of young plants. Specific cultivation measures during the propagation of the plants guarentee a smooth undisturbed initial growth in the greenhouse.

In the cultural information here in front of you we give more specific information that one needs for a optimal cultivation of the cultivar Asclepias tuberosa Red King®. The advices are based on cultivation experiences and experience gained elsewhere. The given advices are indicative and when applied make sure to take the specific cultivation circumstances of the planting site into account.

Cultivation measures

The soil
For an undisturbed growth of Asclepias it is necessary that the soil is airy and has a stabile structure. With cultivation on a full soil the cultivatable stratum needs to be a minimum of 25 cm deep and having a good drainage matters. The soil can not stay wet for too long because otherwisethe roots will start to rot. Preferably, the cultivatable stratum is not a clay soil but peat, sabulous clay or sand. Raised or digged out beds with a for Asclepias suitable substrate can be used when the quality of the soil leaves a lot to be desired.

Field cultivation
It is wise to take a soil samle and to remove fertilizer residues before the start of the cultivation. It is convential to sufficiently water the soil before planting. If necessary fertilize with standard fertilizers. Targetnumbers for fertilizers are different per soil and because of this they are not included in this cultural information.

Asclepias tuberosa Red King® are being planted in a net. This takes place when the net is already layed down on the beds. The cultivar gives straight wide stems so that one layer per bed is sufficient.

Planting Times
In The Netherlands the prefered planting time for the Asclepias tuberosa Red King® is the beginning of March. Flowering will start 13 – 16 weeks after planting, depending on the planting time and the weather conditions during that time. The choice for the right planting time will be made based on the temperature and the situation of the company where the planting will take place.

Flowering times
Overall there are three flowering peaks, depending on the circumstances of the location where the Asclepias will be planted:

  • A spring peak in May
  • A summer peak in July – August
  • A fall peak in September – October (depending on the climate)

Because of the low light intensity and low temperatures there will be no production during the winter months.

Greenhouse climate

Room temperature
To prevent damage during the initial growth and flowering time it is important that the daily temperature stays above 10 degrees celcius.

Light is an important growing factor for the Asclepias. Light has a very positive effect on the quality of the flowers and stems of the Asclepias. That’s why during the season as much light as possible must reach the Asclepias. A greenhouse structure which allows plenty of light and clean glass are important. When the light is too strong it must be possible to offer shade with for instance a chalk coating. This must be done because in the summer the temperatue in the greenhouse can get very high. The result of a too high temperature can that the cultivar does gives less flowerbuds. When there is not enough light in the fall the flowerbuds will dry out. That’s why it is important to also remove the chalk at the end of the summer.

Light exposure (day extension)
Asclepias varieties are quantitatively long day plants. This means the longer the length of the day, the faster new buds will be created by the plant. At days with a length of 12 – 13 hours light the plant will create less flowerbuds than days with 16 – 18 hours of light. There are a number of general rules in regard to light exposure:

  • Daylight extension (16 – 18 hours) in the spring and fall promotes bud formation in the shoots. In The Netherlands there is extra light in spring from the 1 april till 1 may. Extra lightning in fall from 1 august till the harvest
  • Daylight extension lowers the chance of button malformation
  • Daylight extension can be made possible with 18 – 20 watt lamps, 1 lamp per 10 square meter is enough (1000 meter = 100 lamps of 20 watt a piece)

Good hygiene measures always work positive to prevent moulds. If you wish, we have professional photography available of all varieties.

The cultivar Asclepias can create a lot of foliage. This also means that it will evaporate a lot. On average the Asclepias reacts well to large amounts of water. There are no uniform rules for watering this cultivar. The correct amount depends on the greenhouse, temperature, soil and the time of the year.

With sale by auction harvest the branches when there are 5 – 8 flowers opened. With direct sales harvest when the first flowers start to open. The branches should preferably be cut 2 – 5 cm above the ground.
After harvest the flowers will quickly limp. That’s why they can’t lay in the greenhouse for too long after cutting. The best for the flowers is to put them as soon as possible in water. To increase the shelf life the branches get treated with STS (silver thiosulphate). The branches can not stand for too long in STS otherwise the the branches can be damaged. After processing the branches they can be put in water wit a chlorine capsule.

Pests and diseases

Leaf aphids
Characteristics: Aphids can be found on the flowers but also on the young shoots. To prevent this use a good weed control substance.

Spider mites
Symptoms: Small spider like animals suck on the bottom of the leaves. At the top of the leaves grey points will arise. The leaves will turn grey till brown later on.

Symptoms: The leaves on the top will be a bit wrinkled, the flowers stay put and sometimes do not open. When they are opening the leaves will be brown at the points. The damage can occur throughout the year but right after the summer the damage is at its highest point.

Californian Thrips
Symptoms: The Californian thrips are at first sight no different than the normal thrips. However, their way of life is different. The Californian thrips can be found mainly in the flowers and almost never on the leaves. The suction damage can be seen on young unfolded leaves and on the flowers.

Symptoms: On the leaves and the flowerbuds brown spots will arise. At a serious form of Botrytis parts of the plant will rot and covered with a grey fungal growth.

Symptoms: The roots and the rhizome turn glassy and will rot in a later stadium. The cenral cilinders of the roots remain intact and the bark will rot. As a result the crop will wither.

Symptoms: The stems will rot right above the soil. The rotting continues into the rhizome. The chances that this occurs are high after a period of rest.

We ought to give guidelines for a successful cultivation of the Asclepias tuberosa Red King®. Feel free to contact us if problems occur during the cultivation. Green Works wishes you good luck with the cultivation of the Asclepias tuberosa Red King®.

This cultural information is for information purpuses only. Green Works can not be held responsible for mistakes that arise from the said advice.

Asclepias tuberosa Red King® is a brand name and / or breeders right protected, exclusively traded via licence by Green Works International, B.V. Not suitable for consumption.

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