Postbus 336
2400 AH
Alphen aan den Rijn
Rijndijk 263a
2394 CE

Tel. +31 (0)71 3415146,
Fax +31 (0)71 3415829

Click to search the Rhizopon Rooting Guide without introduction.

Every day the technical advisors from Rhizopon visit nurseries where plants are being propagated from cuttings. These nurseries are seeking the latest trends and maintain the highest professional standards. After all, the market is demanding ever larger consignments of plants of high quality uniform plants that have to be delivered at previously determined time.

Meanwhile, a rise in price is practically unthinkable. This, and the fact that many production problems can be traced to cuttings of inferior quality, are  two of  the major  reasons why having  the perfect system of obtaining parental  material (the cuttings) is a minimal requirement.

An important principle is:
A good start (having good cuttings) is necessary for successful production.

Select the best possible parent plants
Years ago, simply taking cuttings of plants growing here and there at the nursery was common practice. Frugal growers even took cuttings from plants in public landscape areas! Naturally (and especially in the latter case), it was impossible to know the condition of the parent plant. Since the best parent plants produce the best cuttings, it is crucial to find a good source of them or to grow them at your own nursery.

Apply an ongoing selection process
During each growing cycle, make a selection of the plants exhibiting the best characteristics to continue growing. From these, choose the best plants to use as parental material.

Select thin cuttings
The location at which the cutting is taken greatly affects the speed at which the cutting will root. From  the  selected plants,  take cuttings close to the base of  the plant. When  taking  cuttings from varieties that are difficult to root, it is advisable to select the thinner cuttings since these will root more easily.

Grow parental plants under controlled conditions
Raise the carefully selected cuttings under completely controlled, ideal conditions. When   growers give their parent plants exactly what the plants need, the parent plants will deliver exactly what the grower needs: super cuttings.

Advantages of tissue culture
In most cases, cuttings taken from parent plants produced from tissue culture produce better cuttings  than ‘ordinary’ parent plants. What’s more, parent plants produced by meristem culture are free of viruses.
Only a well-rooted cutting can produce a good final product.


Rapid rooting is preferable
The faster a cutting takes root, the earlier it will exhibit independence and resistance. A rooted cutting is an independent plant that can produce its own stores of energy. An independent plant is resistant to disease.


Providing the best possible conditions for rooting
A cutting given less than optimal rooting conditions will waste valuable energy. The result will be an inferior root system. To be able to produce its own stores of energy, a plant needs such raw materials as light, water, CO2 and oxygen.

Since light  (whether sunlight or artificial) is accompanied by a rise in temperature, we will be devoting plenty of attention to this factor. Light is necessary for photosynthesis. A cutting without roots is unable to engage in very much photosynthesis, so a little light is sufficient.

More  important at  this stage  is  to provide a  long period of  light over a period of 24 hours (at least 16 to 18 hours) than to expose cuttings to bright light which is accompanied by high temperatures. If necessary, artificial light can be used to extend natural daylight hours.

For a plant, water is just as important as blood is to a human being. This is why a good root system  that can absorb water  is so  important  for a plant. Give cuttings  the opportunity  to develop  the best possible  root  system! Available water  is also  crucial while  the  cutting  is   taking  root. On  the other hand, a substrate  that  is  too dry will cause cell death, and dead cells  increase  the risk of black rot. Another disadvantage of an overly dry substrate  is  that it  encourages  callus  formation.  Although  many  believe  that  callus  is  beneficial  for  root formation, the opposite is actually true. Callus hinders and slows down root formation.
The  degree  of moisture  in  the  soil  can  be measured with  a  tensiometer. This  instrument indicates when the medium is dry, moist or wet. For the best possible rooting, the meter should display a reading between moist and wet. By weighing the trays regularly, you can check to see if they have the proper weight (which can be interpreted as ‘the proper moisture level’). Providing water as based on this information gives the best results in practical situations.

Even for cuttings, photosynthesis is important. So, in addition to light and water, sufficient CO2 must be available. Another advantage of an increased level of CO2 in the air is that it reduces the amount of transpiration (loss of water) through the plant. Cuttings in an environment with sufficient light and an increased CO2 level (800 to 1000 ppm) will root better.

Since oxygen is indispensable for cell division, it is crucial for root formation. This means that the cuttings have to be inserted into a substrate that has a structure which is sufficiently open to allow air (containing oxygen) to reach the developing roots. Also essential are humidity and temperature.

Cuttings without roots must receive the highest possible humidity. Humidity is highly influenced by temperature. When the first roots appear, the humidity can be lowered since the rooted cutting can assimilate better.

To prevent excess transpiration, controlling the temperature is important. The soil temperature has a very direct influence on the speed of rooting. A soil temperature ranging between 20 and 25° is ideal during the initial rooting stage. After this initial stage, the temperature can be allowed to drop a few degrees. To reduce aerial growth somewhat, air temperature should be a bit lower than soil temperature. After all, the cuttings should be encouraged to use their energy mainly for developing roots. Aerial growth will come later.


Rooting regulator
Although cuttings sometimes form roots without receiving a treatment with a rooting regulator, the use of a  rooting  regulator  is extremely valuable. With  the proper use of  these agents, cuttings will form better, more uniform roots in a shorter length of time.

Speed is important; the faster roots develop, the sooner the cutting can absorb its own water.

Uniformity is important to prevent any stragglers from slowing down the production process. ‘Better’  rooting means  that  the cutting  forms  roots all  the way around  the stem, covering several centimetres at the base instead of just forming a single root here and there. Only well-rooted cuttings can develop into top-quality plants.

New methods

To measure is to be sure
To obtain the best possible growth from a plant, it is important to know what is going on in the plant at certain  times. For  this  reason,  it  is advisable  to use  the proper  instruments  to measure the various processes in the plants. There are many sensors available for measuring the various processes in and around the plants. One of these, the tensiometer which measures the moisture in the soil, has been mentioned already. The CO2 level in the air is another   measurable variable, just as is the amount of light reaching the plants. Even the amount of water flowing through a stem and the amount of CO2 absorbed by a plant can be measured.

Computer models
The data measured by the various sensors can be recorded with data-loggers, and the data from the data-loggers can then be read by the computer. This offers the possibility of keeping a very close eye on conditions during the various growth phases. Finally, a growth model can be developed  for  the purpose of controlling  the entire production process. This way, every crop produces a uniform final product.

Rhizopon, working together with growers and researchers all over the world, will continue its investigations in the coming decades. In doing so, we will be basing our work on the latest insights into plant physiology and making use of developments in electronic data gathering and processing.

Go to the Rhizopon Rooting Guide