Crop
The plants are planted out in the substrate in this phase. The transition from the propagation bed to the cultivation bed needs to be as gradual as possible to prevent retardation of growth, and consequently, temperature and moisture shocks need to be minimised. The time of planting can determine the plant’s form at a later stage of cultivation – for this reason, appropriate preparations and tuning are required. A screen/energy screen and/or air humidification can promote vegetative growth. In particular, a high tube temperature can result in a dry climate in which any damaged areas of the leaves dry out too quickly and result in necrotic blotches.
Roots
The volume of the visible plant and the root development under the block are both of importance to the planting time. Once the plant has been planted out in the substrate, the young roots must be able to penetrate the substrate evenly and without obstruction. This can be encouraged by ensuring good contact with the substrate. In addition, the substrate must be brought to a suitable temperature, and preferably, the EC in the substrate should be at a lower level than in the block. This phase continues until the roots have penetrated more than five centimetres into the substrate and the water uptake is no longer dependent on the block’s WC.
Crop
Once the young crop has become accustomed to the climate, the vegetative climate settings can be adjusted to increase the surface area of the foliage, which enables the crop to absorb the maximum amount of light. The 24 hour temperature and air humidity play an essential role in vegetative growth – the right balance must be achieved between the sturdiness and volume of the plant. The first flower development is possible once the crop has reached the required volume in relation to the available amount of light. Although depending on the circumstances, this is often achieved by steering towards generative growth. The climate will need to be adjusted in good time to promote the uptake of sufficient water and nutrients by the plant. This phase continues until the flower development is increasing rapidly.
Roots
The root system needs to be distributed evenly throughout the volume of the substrate if the plant is to make optimum use of the substrate. This can be achieved by controlled watering to ensure that the roots search for water and nutrients in the substrate. However, the drainage percentages must be high enough to be able to provide the plants with fresh nutrients. The vegetative or generative control of the development of the plant also plays an important role. The volume of the roots needs to be as large as possible, as this determines the success of the cultivation of the crop.
Crop
Once the crop feels the burden of the first flowers, the amount of assimilates available for the development of shoots and roots will decrease. The limited light available to the crop must be distributed evenly between the flowers, shoots and roots. Good crop registration makes a major contribution in this regard. In the period leading up to the initial harvest, tailoring the greenhouse climate and the watering regime to the growth conditions will achieve a balanced control of the burdened crop. In the cultivation phase, just before the first harvest, the flowers demand a large proportion of the available assimilates. Once production is in full flow, the crop will have an opportunity to recover. Growth explosions and the accompanying problems with quality can be avoided through the gradual harvesting of this first production.
Roots
The root-hairs that take up water and nutrients have a limited life, which is primarily determined by the availability of assimilates. The activity of these roots is also of importance because the number and development of active roots increases with the amount of water and nutrients taken up by the crop. The root system can suffer a serious reverse on initial harvesting – the skill lies in minimising the severity and duration of this reverse to enable the plant to recover quickly.
Crop
After the initial harvest, the flower development needs to be balanced with the crop’s growth. The crop will use the increasing light for both re-growth and production leading up to the next cultivation phase. This re-growth must not be excessively rapid or intermittent – an appropriate balance must be attained between the vegetative and generative growth of the crop.
Roots
The increased activity of the crop also results in a larger volume of roots, which improves the ability of the plants to take up water and nutrients. In addition, the crop can be subjected to longer, darker periods or weather conditions that do not promote crop transpiration. In these cases, the activity of the roots will need to be maintained by adjusting the greenhouse climate to promote transpiration and water uptake. The watering and nutrient regimes will also need to be compatible with the current demand. Sufficient active roots result in a robust crop that is able to withstand extreme changes in the weather.
Crop
In this phase, the crop’s production rate is high and overlaps with summer and winter conditions. It is important to continue to steer towards a good balance between foliage surface area and flower production all year round. This results in an increased number of harvest points and growth speeds, which is appropriate to the desired quality of the branches. The high level of crop transpiration in the summer results in the need for optimum water uptake during that period. A crop that is growing well and sufficiently cooled by transpiration can often exhibit an exceptional performance in such periods.
Roots
During this cultivation phase, the days with high levels of incident solar radiation require a high uptake of water and nutrients. The water uptake is particularly high during the extreme hours – around the middle of the day. Both the watering and water buffer in the substrate volume are of essential importance to the availability of water and, consequently, to the crop’s uptake of water. A root system distributed evenly throughout the substrate is able to take up more water and nutrients, and in turn, this is beneficial to the transpiration from and cooling of the crop. Besides the provision of sufficient water for maximum uptake, it is important that the roots are kept healthy by timely modification of the watering regime in response to changes in the weather. In the winter period, it is important to encourage sufficient root development by delaying the commencement of watering until later in the morning and then administering larger volumes of water each time.
Crop
The crop’s performance often declines gradually. Nevertheless, it is still important to achieve maximum production and quality. In this phase, the crop’s vulnerability to disease increases as the crop becomes more passive and weak. If at the end of cultivation non-standard crop measures are used, the result may be a negative influence on the quality of the branches to be harvested. Until the end of cultivation, it is important to continue steering towards an increase in the foliage surface area and to guarantee the optimum water uptake (as explained in Phase 5).
Roots
Despite the age of the crop, it is still important to retain sufficient healthy roots. It is also important that the substrate drains well. Subsequently, the replacement of the nutrients in the substrate must be kept at an optimum level. If at the end of cultivation non-standard crop measures are used, the result may be a negative influence on the quality of the branches to be harvested. Until the end of cultivation, it is important to respond to changes in the weather promptly (as explained in Phase 5) and adjust the watering in good time to achieve maximum water uptake.