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Irrigation

Watering

There are different watering systems that can be used:

  • localised irrigation, gives the best conditions for disease control.
  • sprinkling is less labour-intensive but not suited to cyclamen
  • irrigation from underneath (subirrigation) by ebb and flow or gutter is not costly in labour.

> Introduction

There are various methods of watering. We shall describe them here in turn, and our discussion of the advantages and disadvantages of each will be based on documentation available from the (French) National Horticultural Industry Committee.

> Localised watering

Water is brought to each pot individually, usually at one point on the surface. It then moves towards the bottom of the growing medium. It is brought to the pot by a capillary tube (pipette dripper) or a drip feed inserted into the water supply pipe (in-line dripper). In either case the dripper is sited halfway between the plant’s collar and the edge of the pot, so as to ensure a good distribution of water throughout the medium and avoid making the immediate neighbourhood of the collar too wet.

 

This method is very economical and has the further advantage of allowing the grower to know how much water is being used on the plants.

Installation, on the other hand, is a fairly long process and quite a heavy investment cost. In use, the drippers must be checked because they are liable to become blocked, especially when the water used contains a load of mineral salts.

The use of this watering method requires a medium that is readily wettable by capillary action, otherwise the water will make channels from dripper to drain-holes, wetting only the few favoured parts immediately next to these. Any kind of growing medium, then, that has poor absorbent properties must be ruled out.

> Sprinkler watering

With this method water falls onto the plants’ foliage from above. The equipment that may be used includes:

  • spray heads which sprinkle onto a circular area, or a sector of a circle. This equipment is simple and quick to install, and the least laborious to use. The spray heads must be well positioned, though, for sprinkling to be uniform.
  • oscillating tubes which sprinkle a rectangular area, giving a better distribution than the spray heads.
  • automatic-progression watering trolleys with one or two sprinkling tubes and drippers. These do ensure uniform watering, but require a large initial outlay.

 

With the sprinkling technique it is not so easy to make the quantities given conform to the real needs of the plants: and if fertiliser is to be combined with watering using this kind of equipment, then there is a large waste of fertiliser which draining away with the water that falls on the staging.

When all is said and done, sprinklers are not the ideal method for cyclamen.

> Irrigation from underneath (subirrigation)

The basic idea of this method of watering is to bring the water or nutrient solution to the base of the plant pots and use the capillary action of the material in the pots to draw up the moisture. The liquid stays for a while in the medium, and then drains under gravity.

This method of irrigation is very widely used in northern Europe, especially for mini cyclamen.

1 > Fill and drain (ebb and flow) system

The pots are on a table where the level of water or nutrient solution can be kept at one third or one quarter of the height of the medium. The irrigation is planned so that short periods of wetting (around 15 min.) alternate with periods of drainage as the tray is emptied. The bottom of the tray is usually made of polystyrene, and it should have channels so that the liquid empties away better. The support needs to be mounted as level as possible so as to avoid any irregularity due to some parts being higher than others.

Setting out the plants at their final distance is easy with this arrangement; however it creates a climate just around the plants which encourages wilting. Watering is also a long business (first filling, then emptying), and sometimes not wholly regular.

2 > Trough system (flow down a gutter)

The base of the pots is on a slightly inclined trough (1:200), and an intermittent stream of water or nutrient solution flows down the base of this, wetting the growing medium by capillary action. These troughs are usually made out of aluminium.

The gutter system is less flexible, since the troughs themselves are fixed; but they have the advantage of allowing a good circulation of air around the plants. In this case the watering operation need not last long.

A March 1994 article (E.Grantzau, Beate Ter Hell, in the journal TASPO ; in German) reports a greater effectiveness for this system than other irrigation techniques.

3 > System using a medium for water transfer

The pots are placed on a watering mat (made of rot-proof, porous material) or sand, which transfers the water it contains to the growing medium by capillary action.

Keeping this material wet also helps to maintain a moist atmosphere.

 

Another variant, the flood floor, is to place the cyclamen directly on a concrete slab. The slab is then immersed to a depth of a few centimetres and this provides the watering.  It is a method that suits monocultures well since it may be highly mechanised or even automated. Designing and installing these systems is precision engineering and must be done by specialists.

 

To sum up, irrigation from underneath has a number of advantages, whichever the system adopted (time saved, uniformity of the plants, easily automated, efficient use of glasshouse area, &c.) On the other hand, it does require high grade equipment, careful installation and the grower’s skill and experience. The method relies on a real understanding of cyclamen culture, but also the use of suitable growing medium and the right choice of pots.

 

The growing medium must be very well aerated (the roots must breathe) and of a nature to allow water to rise by capillary action. The pot must be one which allows an adequate area of contact with the material underneath but which also allows a sufficient circulation of air. These aims need to be reconciled by using the right medium and suitable pots.

 

It is harder to control the capillary rising of moisture in the medium than to control the flow of water under a gravity-based system, where the water essentially drains downward.

When both water and fertiliser are supplied from underneath, there must be a washing out of accumulated salts every 15 days by means of sprinkling from above.

 

Lastly, it should not be forgotten that the use of irrigation from below, in troughs or with a transfer medium, does involve the danger of spreading disease.

> The watering mat

This widely known system of irrigation has many specificities.

Which mat to choose for the culture of cyclamen? 

How to water it? 

Which substrate is adapted? 

Which type of pot

How to maintain it?

 

To answer these questions and to find easy and practical tips, download our new culture factsheet: « The watering mat ».

 
PDF - 1 Mo

> How to arrange proper adjustment of watering

It is possible to arrange for continuous measurement of the plants’ evaporation and transpiration, in order to calculate water requirements, by means of a precision balance connected to a data recorder. Indirect calculation methods enable us to establish a value for the water requirement and initiate watering automatically. But this is a tricky and costly system to install.

 

There are currently two different approaches of practical application in the glasshouse for controlling watering as a function of plant requirements.

 

Recent work (Rivière et al, 1991), and trials at the Angers research station of the National Industry Committee, have shown that it is possible to use tensiometers with electronic pressure gauges, devices which are able to record very slight variations in water potential in the medium.

 

Management of watering is extremely important, because with it comes mastery of the factors that determine growth, and their application; and that is the way to control growth itself.

> References

RIVIÈRE L.M. et al.- Mesure du potentiel hydrique des substrats de plantes en pot au moyen de tensiomètres. P.H.M. Revue Horticole, n°316, Avril 1991, p. 33-39

 

URBAN L.- Introduction à la production sous serre : l'irrigation fertilisante en culture hors-sol (tome 2). Technique et Documentation, Lavoisier Editeur (France), 1997, 210 pages

Caution

This advice sheet is based on the methods used at the SCEA at Montourey (Fréjus, France). These procedures may need some modification to adapt them to other climatic situations. Before starting to grow cyclamen there needs to be a review of precautions against pests and diseases.   We must point out that our advice and suggestions are offered for information purposes and therefore cannot include any guarantee of specific results; it is a good idea to carry out trials beforehand.

 

Irrigation :

S.A.S Morel Diffusion

2565, rue de Montourey
83600 Fréjus - France

International telephone : +33 (0)4 94 19 73 04
Switchboard : + 33 (0)4 94 19 73 00
Fax : +33 (0)4 94 19 73 19

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