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This Rose cultivation-growing guide is made by;

 Roskam Young Plants Pty. Ltd.

P.O. Box 44

Clarinda, Victoria 3169, Australia

Mobile: 0418 356937    Fax: 03 9551 0217   

Website: www.roskam-youngplants.com
E-mail: info@roskam-youngplants.com 

And

PREESMAN B.V.

Website: www.preesman.com

E-mail: preesman@preesman.com

PREESMAN B.V. is a breeder a company specialized in, Alstroemeria, Chrysanthemum, Gerberas and Roses.

Although we trust that this cultivation guide will be of considerable help to the success of the crop, we cannot accept any liability for the results of your crop. All the information in this guide is without committing ourselves. 

1.  Introduction.

Roses are the most popular cut-flower world wide.  From the early days, many new varieties have been selected aiming at an improved product in both cultivation and cut-flower aspects, like the improving yielding capacity the improved yielding capacity, the improved production, and the improved distribution of harvestable product throughout the year. Another important aspect which has a effect for price development of the product are the improved quality aspects, like flower and stem quality to guarantee an optimal vase life and satisfied customers.  Very important in the evaluation of rose quality is the ability to complete the process from bud till ripe flower.  The large range in colour, size, and fragrance, allow roses to be selected for each occasion and purpose.  With this in mind, Preesman aims at creating a product with optimal amount of these qualities in each new variety. 

1.1 Selection process 

Seedlings are the starting point of breeding and the selection of our roses. The seedlings are then grown as cuttings on their own rooting system in an artificial substrate.  The use of certain growing techniques, like for example the use of selected rootstock material, may even prove to increase the quality of the selections offered.  This aspect does also have a lot of attention of the people at Preesman.  Another development which already has been given a lot of attention and has been generally accepted is the change in cultivation practices. Preesman offers a cultivation system, which allows an improvement of all quality aspects mentioned previously.  The concept is to control the plant as growing unit to a maximum. In that respect we try to improve the technical requirements of the system.

All these efforts resulted in a range of new varieties showing the rose growers: 

We, from Preesman B.V. and Roskam Young plants Pty Ltd, would like to help rose growers to make the Preesman rose varieties selected by them into a successful crop. Our experience in different production areas all over the world, guarantees a well-founded advice for your own special conditions. 

For the Australian market; Job Roskam of Roskam Young Plants Pty Ltd is the exclusive agent of the Preesman Rose varieties. 

For the New Zealand market; Moffatt’s flower company in Christchurch is the exclusive agent of the Preesman Rose varieties. 

2.  Growth factors.
 
2.1    Light.

Light is the growth factor which influences both temperature and water, unfortunately it is also the factor which we can control the least. Too much light must be taken away by shading.  In areas with a constant high radiation, shading often is done outside the glasshouse. This has a positive effect on temperature control.  In areas with changing conditions, a movable screen inside the glasshouse is recommended. However, this often has negative side effects as temperature increase and through a reduced evaporation; a less active crop is created.  As our control over the plant processes improves, shading becomes less necessary. Low light intensities can be improved by applying artificial lighting, which has only a limited effect. It does have some major drawbacks; cost increase, influence on the glasshouse temperature, and the shadow of the installation on the leaves when illumination is not required. 

*     Primarily light is necessary for assimilation (photosynthesis). Through chlorophyll in the leaves, light is transformed into sugars, a process also requiring CO2 and water. This energy source is essential for growth and development of flowers, stems, leaves, and roots.  The degree to which a plant can use the amount of light available depends on several factors, for example chlorophyll contents of the leaves, CO2, temperature, and humidity.  Each of these factors can prove to be a limiting factor on plant growth.

*     Another, more indirect, effect of light is the stimulation of vascular transport through the plant.  As light raises the leave temperature, the leaves respond by opening the stomata to allow a higher evaporation in order to cool down.  This process also increases the water transport, enabling nutrients, necessary for plant growth, to be distributed through the plant. 

2.2    Temperature.

Temperature influences almost all processes of life.  Therefore its relation to radiation should be established.  This relation is mainly determined by the production of sugars. Too much light at a low temperature causes an unnecessary surplus of sugars.  Even though this is undesired, the other way around (high temperature with low radiation) should definitely be avoided.  Due to the high temperature the respiration process works at maximum capacity, while production of energy (photosynthesis) is maintained at a low level.  A shortage of energy will be the result.

Temperature is often taken over a 24-hour period, when its relation with light is discussed.  The differences in temperature during the day/night (light/dark) period have a major effect on plant growth.  It is assumed that through a raise in temperature early in the night period, more energy is put in generative growth (flower development).  Higher temperatures during the night period, compared to the day period, will stretch internodes and vice versa.  Under poor light conditions this is a possibility to obtain the required 24-hour temperature without creating a weak and elongated crop. 

2.3    Water.

Water plays a very important part in the assimilation process, in transport of sugars and nutrients, and in the cooling system of the plant. 

A plant consists for over 90% of water.  The plant is kept upright by regulating water pressure (osmotic systems).  Evaporation is influenced by factors like light and temperature, and to a lesser extent by humidity.  Stomata control evaporation; poor water supply will result in a closing of stomata with subsequently no gas exchange and no production of sugars (energy).  Therefore it is important to keep a check on water uptake and evaporation.  If the evaporation is larger than the uptake (wilting!), the most efficient control measure is light reduction. 

Water uptake can also be improved by applying directly at the plant (drip irrigation), and by reducing the salt concentration in the water (E.C. or total nutrient value).  When evaporation is low and extra light is not available, try to reduce humidity by increasing the temperature. 

Besides a sub-optimal use of light, too little evaporation does not provide an optimal sugar and nutrient transport, resulting in e.g. calcium and magnesium deficiencies.  It is important to stimulate evaporation on the total plant canopy.  Therefore, vertical temperature differences should be avoided.  This can easily be achieved by using a heating system at the base of the crop. 

3.  Substrate cultivation.

After the previous paragraphs on growth factors, it may have become clear that a complete control of environmental conditions will result in an optimal growing climate.  However, complete control is not possible.  Since substrate cultivation allows more control than cultivation in soil, it is often recommended.  Soil quality (chemical and organic structure) and the possibility of soil sterilisation should be compared to the additional cost of setting up substrate cultivation before a decision is made on which practice is preferred. 

3.1    Substrate choices.

Many different types of organic and an-organic substrates are presently used.  For growing roses; rockwool and cocopeat are most frequently used and preferred.  In Australia cocopeat in slaps or pots is the most used growing media.
 

 3.2    Requirements for substrates.

·    Good air/ water balance.

·    Good draining and leaching capacity.

·    PH neutral and containing none or very few nutrients.

·    Stable structure, even in the long run (no or little decomposition).

·    Offering sufficient support to the crop. 

3.3    Cocopeat.

Cocopeat is a waste product from the coconut palm (Cocos nucifera). Presently it is originating from for example Sri Lanka.  In fresh material a relatively high E.C.-value is measured (caused by e.g. sodium, potassium, or chloride). This material is very easily to rinse causing these nutrients to leach.  Rinsing often is done at the place of origin, using local rainwater during the monsoon period.

Still a chemical analysis should be completed since high salt concentrations cause serious growth reductions.  Cocopeat can hold both water and air.  Remarkable is the ability to take up water even after severe drought.  Stability of cocopeat is presently experienced to be good, even after several years little physiological changes have been recorded. 

Cocopeat is pH neutral, at a value around 5.5 - 6.  At fertilisation one should be aware of potassium present in the cocopeat. Therefore often a dose (1-2 kg/m2) of calcium nitrate (CaNO3) is applied at the start of cultivation.  Initially a fertilisation schedule could be used replacing potassium nitrate (KNO3) by calcium nitrate.  Please, check the iron (Fe) content regularly; it has been observed that cocopeat may retain iron temporarily.

During cultivation the pH can be adjusted by applying acid and or ammonium nitrate in the nutrient mixture.

Water supply does not much differ from rockwool; perhaps cocopeat requires a little less water.  Cocopeat is used in bags of 15-cm wide by 1 metre length or filled direct in plastic pots.   

3.4    Rockwool.

In choosing rockwool you could take a slap of 7.5 cm by 15 cm by 100 cm (height x width x length).  The quality (durance) of the slap is an important characteristic to take into account when purchasing (see and feel!)  Since roses are grown for several years on the same piece of rockwool, the quality should be maintained for a longer period.  Often special types are available, even though these might be a bit more expensive, the effects of an optimally operating rooting system will become noticeable after some time. A hard rockwool slap has got sufficient air/ water capacity. The alkaline nature of rockwool can be corrected by saturating the bread with a nutrient solution at a pH of 5.3-5.5. During cultivation the pH can be adjusted by applying acid and or ammonium nitrate in the nutrient mixture.

4.  Cultivation systems.
With the cultivation systems recommended by Preesman Roses, the plants are grown 30-40 cm above the ground.  This height is necessary to provide space for the bend-out stems and provide enough air circulation through the crop.  This improves the evaporation and increases the amount of active foliage.  If heating is required, it also allows the tubes to be places underneath the plants.  To obtain the elevated flowerbed numerous systems can be developed and several are readily available on the market.  When applying drains it also offers sufficient space for installation of gutters.  If cultivation in pots is desired, various systems have been developed to allow optimal use of space (frameworks of iron).  Since too many systems have been developed we can not deal with all of them specifically, but we like to draw your attention to the fact that each system should have sufficient draining capacity and all irrigation tubing should be level. 

4.1    Setting up cultivation. 

We recommend cultivation in a so-called 2-row system.  Per compartment of 6.40 metre 6 rows of plants are planned.  The distance between the plants in one row varies around 15-20 cm.   

This results at 7 to 8 plants per Metre Square (depending on cultivar and cultivation system).  In the paths between the plants tubes are planned for heating.  These pipes may also be used for transport of carriages.  The maximum water temperature should be kept between 40-50 degrees.  To provide an optimal CO2 supply, on each flowerbed a tube for CO2 supply is recommended. 

4.2 High lines of the grow system.

-          Plants are placed approximately 35 cm above the ground.

-          Bend-out branches have more space, which improves leaf functions and so create more energy.

-          By bending out branches the top of the plant stays at the original place and only basal shoots are formed.

-          At harvest, cutting is done just above the original top, giving maximal stem length.

-          More uniformity in production between plants gives a higher production per m2 of a higher quality.
 

4.3 Drip irrigation. 

A (well installed) drip irrigation system is recommended; as each plant receives the same amount of water. By supplying the water directly on the potting mix, the plant itself does not become wet (so preventing diseases).

The dripper line of the irrigation system are placed on the ground between the two rows, this prevent the dripper line becoming empty, and keep the water temperature low and the dripper line out the reach of direct sunlight. 

4.4 Drippers 

A capacity of 2 litres per hour is preferred as the chance of congestion is smaller.
By using a drip system, a wet (water) column is created through which the roots grow.

Place the drippers by planting in the jiffy pot, after 2-3 weeks when the roots are growing out of the jiffy pot in to the potting soil replace them approximately 1 - 5 cm from the jiffy pot.

5   Cultivation.

5.1    Start of cultivation.

At the start of the cultivation a glasshouse temperature of 20 – 24 degrees is recommended.  The relative humidity should be high.  Fertilisation is in these initial stages done with an extra 20% calcium nitrate.  As soon as the first basal shoots have developed well, it should be returned to normal levels.

The water supply, i.e. the frequency and amount of drip irrigation, is depending on the time of year and the development rate of the crop. Check the amount drain regularly (minimal 35 - 45% overdrain).  The water gift per dripper is at least 70 - 80 Ml. per irrigation turn.  When smaller gifts are used the irregularity between drips becomes too obvious.  At saturation and the initial weeks of cultivation, the E.C.-value of the nutrient solution should be lower than the E.C.-value of the plants in the jiffy pots you receive from the propagator.  This stimulates root growth and results in a rapidly established crop. 

After this initial period the E.C.-value of the water gift varies around 1.5 – 2.0 depending on the time of year.  The PH of the nutrient solution is maintained preferably between 5.3 – 5.5.  If the PH-value in the drain water rises above PH 6.0, some ammonium nitrate could be applied.  If the substrate used is cocopeat, often less ammonium nitrate is required.  Besides chemical analysis of the drain water, the cocopeat media itself could be analysed. 

5.2    Crop maintenance after planting. 

After planting, shoots will quickly develop. Only after the flower bud becomes clearly visible the shoots are bend-out and the flowers are removed.  Since the plants grow about 40 cm above the ground, it is possible to bend down the stems deeply.  Be careful not too break the shoots, the plant should remain capable of transporting sugars from these areas to the new developing shoots.  The shoots should be bend down so the grafting place or, if a cutting is used, the old top of the cutting will become the top of the plant.  The flower buds on these bend-out shoots have to be removed.  This system allows the leaves to continue their production of energy. When the dominating primary shoot (apical dominance) is removed, causing the plant to respond by developing more basal buds.  In the plant hormonal changes take place, which promote shoot development (balance cytokinins/ auxins).  After cutting or bending out results in an increased cytokine level, causing buds to break.  The shoots formed are producing auxins, so restoring the hormonal balance in the plant.

5.3    Basal shoots.

Depending on the growth potential of a cultivar a number of basal shoots are formed. Per plant 2 to 3 well-formed shoots are allowed to continue growing, if more shoots were formed we recommend bending out of these shoots.  This way a plant has got the use of more active leaf canopy to supply enough energy for development of a heave crop with first quality flowers. 

5.4    Harvest.

At harvest it often was practice to cut back to the first so-called 5-leaf.  We recommend cutting back to the just above the original cutting.  The length of the remaining stem decides the number of shoots (flower stems) which will grow back.  If too much (4-6 cm) stem is left, many shoots are formed of a poor quality.  Therefore we advise to cut back to  1 cm.  After 1 to 1.5 year the rose bush is cut back to approximately 10 cm above the original cutting, so creating a new top.  Now again only  1-cm stem is left after harvest.  Naturally differences do exist between cultivars, in case of doubt do not hesitate to contact us. 

5.5 Crop maintenance.

From all these points it becomes clear that leaves provide energy (source), while the flowers are the main users of this energy.  Therefore it should be common practice save a maximum of leaves. The leaf area is maintained while the flower bud is taken out as soon as possible, since we would like to keep the original top of the cutting, or grafting place, the apex of the plant.  The leaves now will be lower than the apex, while care is taken to avoid too many leaves from over lying.  The shoots should be bending out carefully to avoid internal damage; this will block the transport of sugars and nutrients and so creates sub-optimal growing conditions.

By maintaining differences in developing rate per shoot a crop will be more heterogeneous.  This will allow a more equal distribution of energy in time. 

5.6 Climate.

Regulating the glasshouse climate should be done in order to keep the leaf canopy active.  Especially when much light is available (sunny conditions), heating under the crop is recommended to prevent large temperature differences in the crop.  When less light is available, heating both under as above the crop will be necessary.  To remove excessive humidity from the glasshouse, the heating should be combined with ventilation.  This depends on the difference between outside and glasshouse temperature and varies with the ventilation possibilities of the glasshouse. In general with modern glasshouses we recommend ventilation at outside temperatures of 10 degrees or higher.  This also is depending on the wind speed; under windy conditions the ventilation rate will be higher.

5.7 Stem length and bud size. 

To increase the stem length and the bud size, you have to prevent stress situations.

1. It is very important to keep the heat out of the greenhouse. This can be done by;  

·        Use shade screen with aluminium reflection parts.

·        White washes the greenhouse.

·        In summer start early with ventilation.

·        Also in-house misting system (above or under the crop) can help you to increase humidity and reduce the temperature in the greenhouse.

·        Installing roof sprinklers; Roof sprinklers can reduce greenhouse temperature with 2 till 3 °C.  

2. Drip EC level during period of (extreme) high temperatures and low humidity's, can be reduced till 1.2-1.4. By reducing the E.C. you make the water easy available for the plant. 

3. You need to check regularly (manual) the PH and EC in the drip and the drain water by the plants in the greenhouse, Avoid extreme fluctuations. Use alarm system to avoid extreme values, but don’t rely only on the irrigation computer. 

4. You can increase the amount of cycles in summer. Water cycles of more than 100 ml per plant per cycle could be used. This way you also make the water more easily available for the plant. 

5. Especially in extreme circumstances you need a lot of leaves on the crop. It would be good if you stop harvesting for some weeks in summer (when it is very hot). You only take away the buds/flowers. The plants can build up energy for the new production season. Quality and stem length will increase this way. The amount of ground shoots will increase also.

Do not take too much leaves form the plant. It makes it harder to cool and recover. 

6. The crop has to be healthy: white roots, no pests and diseases (like Pythium, Phytophthora, downy and powdery mildew, spider mites). 

7. Do not allow explosion of spider mites (two spotted mites or red spider)

Important items are: 

·        Scouting and instructing workers to mark infected spots.

·        Spray as soon as you see an infection (on the spot or whole greenhouse)

·        Spider has to be in contact with chemical. Spray especially at bottom of the leaves

·        Use a lot of water (3000 till 4000 litre per ha.)

·        Spray with a high pressure, with a very fine mist.

·        Spray again adult + nymph + larva + eggs at the same time!

·        Spray same combination 2 till 3 times. Than it has to be replaced by other chemicals

·        By warm / hot weather the mites multiply very quick, so spray at least every 4-6 days in summer.

8. Stem length and bud size is mainly influenced by temperature.

High temperatures will reduce stem length because the bud development starts earlier.  

Ideal temperature range; 

Day temperature  :    between 20-21 degrees.

Night temperature:    between 16-17 degrees.  

*** The night temperature has to be at least 15-16 degrees. Lower night temperatures will give blackening/browning of the petals of the red varieties. 

6. Rose root problems. 

As you know it is very important to have white root development. If the roots are not healthy, one of the following symptoms could be shown; 

·        The stem length will decrease.

·        The bud size will be smaller.

·        The leaves will be smaller.

·        The colour of the flower could change.

·        The crop will show deficiencies, and leaves will become yellow and will drop.

·        The crop will also be more sensitive for pest and diseases. 

The following items can cause a bad root system:  

6.1 Bad water management (too much and/or too frequent).

The total drain amount during the day has to be ± 35 / 45 %.

During the first cycle in the morning (1 / 1.5 hour after sunrise) there should be no drain. If you have drain during the first cycle you stopped too late the day before or you give to much water per cycle. 

The total amount of water take-up by the plants per m2 per day could be around 5 / 6 litres (if there are a lot of leaves). If the flush is gone or the crop is not very healthy or the evaporation is low (high humidity), it might be enough to give 3 / 4 litre of water per m2 per day. The minimum amount per cycle has to be about 60-80 ml per plant.
Between the cycles the cocopeat or rockwool can dry up a bit. This is important for the amount of air (oxygen) in the substrate. If you are giving a small amount per cycle, you have to give a lot of cycles to realise 40% drain. After each cycle the substrate is maximum wet so each time the amount of air in the substrate is low.  

**** It’s better to give less cycles and more water per cycle. 

If the flush is gone or the crop is not healthy (less evaporation), and you keep on giving the same amount of water, you will see that the drain % will increase. If the drain is above 50 %, you have to reduce the amount of cycles (stop earlier) or reduce the amount of water per cycle. 

During the night the plant does not assimilate en does not evaporate a lot. For this reason you should not give any water during the night. The roots have to be drier during the night. Stop giving water about 2 / 3 hours before sunset. 

IT IS VERY IMPORTANT TO MEASURE THE AMOUNT OF DRAIN!!! 

6.2 guide for the water management. 

During the data collection you can think about the following items; 

Do you see difference between the crops/varieties in drain amount?

Do you give the same amount of water to all the varieties?

Do you give the same amount of water also when the flush is gone?

When do you start giving water? When do you stop?

What is the drain amount after the first drip cycle in the morning?

Do you still give water during the night?

What is the humidity during day and night in the greenhouse?

What is the influence of the humidity change on the drain %?

What is the influence of the temperatures on the drain %? 

6.3 Bad drain system (wet spots) (water logging). 

Root problems also can be caused by a bad drain system, especially when the cocopeat or rockwool is too wet most of the time. Because of this there is not enough air in the root environment. This causes fungi like Phytium and Phytophthora.

It is very important that the cocopeat or rock wool can drain easy, blocked drain or level difference in the bench systems could course too much water around the roots.

In general you can say that water is no problem as long as it can drain out very easy.

***Without a good root system you will never get long stems, big buds and big leaves.  

6.4 Wrong pH and or EC.

It is also important to drip with water of a pH between 5.3 and 5.5 for keeping a healthy root system!

If the pH is too high a lot of elements cannot be taken by the plant. Some of these elements are for root development. A high pH (above 6) or a low pH (below 5) can cause root problems and it’s also a cause of deficiencies in the crop. This will cause again a bad root development. 

If the EC is (very) high (above 2.5) the roots cannot take the water (and nutrition’s) easy. A (very) high EC is causing short stems, small buds, small, thick and dark green leaves.

If the EC is very low, deficiencies can occur. When the temperatures are high and the humidity is low, it is good to give an EC between 1.2 and 1.4. This way the plants can take the water very easy (osmotic system in the roots). If the humidity is high, it is good the give water with a higher EC level (1.6 till 1.8). In the small amount of water the plant is taking in high humidity circumstances there are a lot of nutrition’s. 

The EC of the drain water can get too high (above 2 / 2.5) when the EC of the dripping water is too high or by a too low drain percentage.  

6.5 Wrong fertilizers, too much or too less of some elements.

Problems with the roots and the crop also can be caused by the use of the wrong fertilizers or a wrong balance between the fertilizers. 

To know the amount of elements it is a must to analyse the water at least each month. Please contact us to get information on how and where to test the drain water and or growing media.

6.6 Diseases (Pythium, Phytophthora, Cylindrocarpon, Cylindrocladium, Fusarium).

Spores of most of the fungi are always present. If the circumstances are good for the fungi they will develop and the roots will start getting brown.

If there are a lot of brown roots in coco peat or rockwool, you have to find out why this happened. A treatment with fungicide could help, but only solve problems on the short term.  

*******It’s important, when you have growing problems or diseases, to find the solution. Keep on doing trials and tests on a small scale to find out how to solve the problems.  

If you drench the plants (+/- 100-150 ml water + chemical per plant) you have to make sure that the plants are thirsty. Before the drench/treatment stop the watering. After the drench/treatment you should not give water for half a day. You can give the drench/treatment early morning or instead of the last drip cycle. 

6.7 High root temperature, which causes Phytium and Phytophthora.

Root temperature should not be above 25 C. For this reason it is very important to cover the stock tank with a roof (it has to be able to ventilate). 

6.8 Not enough green leaves!

A bad root development can also be caused by an unhealthy crop. Infection of insects, fungi or other diseases will decrease the amount of green leaves. A low green leave amount will cause bad growth of leaves and roots. A low leave amount can also be caused by harvesting too much stems. 

7. Fertilization. 

An irrigation unit with an A + B tank is preferred to give the exact quantity of nutrients to the plants. The EC and the pH are measured by the irrigation unit and directly corrected.
 

7.1 Fertilizer program: 

(Note: this fertilizer program gives an indication of what you could use, this fertilizer solution could change because of the type of water and how the plants are growing.)

Tank: A = 1000 Litre 

Tank: B = 1000 litre 

Trace elements:

*    This depends of the PH of your drainwater, if drainwater PH below 6.0 you don’t
      need Ammonium Nitrate in the fertilizer tank.
**   When the PH from the drainwater is above the 6.5 / 7.0, you have to use EDDHA
      iron.

*** This depends on the PH of the type of water you use e.g., rain, dam, bore water.

****Always check if you use sulphate or chelate, and what strength the trace  
      elements are!!!

***** You could add Agri Potash (Potassium Carbonate) to increase the PH of the drip irrigation water. 

7.2 Optimum EC & PH;