Objective phase
Fast and uniform rooting in, so that the roots are penetrating the growing media in line with the plant size.
Target crop
Uniform growth and equal development of the stems should continue and the leaf area should increase to enable the plant to intercept as much radiation as possible.
Target root zone
The pin roots should grow easily out of the block and uniformly into the growing media. It is important to supply enough water and nutrition to the blocks until the plant can rely on the available water in the slab.
Start of phase
Plants arrive into the greenhouse.
End of phase
When the roots have penetrated into the growing media several centimeters and water absorption is no longer dependent on the moisture content in the block.
You have two options for cutting the drain holes. Option 1: Pre-draining the slab by puncturing the plastic wrapper with a small hole just above the seam will create a small reservoir of water at a uniform height in each slab throughout the greenhouse. This layer of water ensures that the propagation block will remain sufficiently and uniformly wet so in the first 48 hrs after planting (even if you have previously stood the plants beside the plant hole) only 1 or at most 2 irrigation sessions will be required to stimulate root penetration into the slab (applies to Plantop Delta and Grodan Pro blocks only).
This way of cutting the drain holes is the preferred choice for 10 cm high slabs.
Stop irrigating from the moment the plant is rooted 2 - 3 cm into the underlying slab and until the final drain hole is cut, which will be after 4 - 7 days. Ideally the final drain hole can be made by cutting along the width of the plastic seam with scissors or by cutting one hole on the side of the slab at its lowest point.
It will find it easier to cut the drain hole while there is still excess water in the bottom of the slab effectively pushing on the side-walls of the plastic foil.
Option 2: If you wish to cut the drain holes directly, first drain the excess water from the slab by making a small puncture just below the plastic seam. Return to the slab once it is drained and cut one drain hole per slab, at the end of the slab or ideally by cutting along the seam across the width of the slab.
| Bright day - Vegetative steering | Dark day - Generative steering | ||||||
| Start time | First days during rooting in irrigate every 4.0 - 5.0 hrs (subject to way drain hole is configured) | First days during rooting in irrigate every 4.0 - 5.0 hrs (subject to way drain hole is configured) | |||||
| Stop time | Not applicable | Not applicable | |||||
| Target day level WC | Slab >70%, Block >50% | Slab >70%, Block >50% | |||||
| Target decrease WC overnight | Not applicable | Not applicable | |||||
| Moment 1st drain | Not applicable | Not applicable | |||||
| EC drip | 3.0 - 3.2 mS/cm | 3.2 - 3.5 mS/cm | |||||
| EC slab | 3.0 - 3.5 mS/cm | 3.3 - 3.8 mS/cm | |||||
| 24 hr drain | Not applicable | Not applicable | |||||
| Irrigation volume | 80 - 100 ml/block | 80 - 100 ml/block | |||||
| ml/joule | Not applicable | Not applicable | |||||
| Night irrigation | If decreae >20% | If decreae >20% | |||||
Before planting, it is essential to fully saturate all the slabs with nutrient solution for at least 24 hours before the drain hole is cut. This ensures that even the fine pore spaces between the NG2.0 fibres are filled with water. There are two ways to cut the drain hole. For Prestige 10 cm slabs the preferred method is by first pre-draining the slab. Prestige 10 cm is designed to promote generative plant development providing maximum synergy between root zone and climate strategies. In order to facilitate maximum generative - vegetative steering of WC% and EC in the root zone throughout the duration of the cultivation you are advised to cut one drain hole per slab. Remember with Prestige 10 cm it is perfectly safe to recycle the drain water from the moment the drain holes are cut. This will help reduce unwanted emission of fertilizer to the environment.
Objective phase
Set the first fruits at the desired internode and continue their development and the realisation of a root system that fills the entire volume of the growing media.
Target crop
Work on plant development and increasing the leaf area to capture the available radiation and keep the required vegetative – generative balance in the plant relative to the fruit load and light levels.
Target root zone
Establish complete root penetration in the entire volume of the growing media. This will enable the plant to take up all the water and nutrition it will need for maximum summer production and quality.
Start of phase
When the roots have penetrated into the growing media several centimeters and water absorption is no longer dependent on the moisture content in the block.
End of phase
When the plant starts to feel the effects of the fruit load.
The crop is now rooted into the slab so ensure your GroSens sensor is positioned in the slab correctly. Watch the video below on how to do this correctly.
On cloudy days the need for water will be dependent on the developing fruit load and the condition of the crop in combination with other climatic factors such as pipe temperature and venting. Therefore the starting time of irrigation must be continuously adjusted to the crop's condition and the climatatic conditions. In the morning the WC% graph should first show a sharp decrease in WC% before irrigation can be started.
On sunny days the young fruits will swell during the early evening hours. Therefore depending on the climatic conditions and ventilation strategy water uptake may continue until late in the evening. This will be clearly visible on the GroSens graphic. If the WC% decreases too fast (>4% within 3 hours of stopping) it may be necessary to give an extra irrigation around 23:00 hrs.
In the coming weeks you will clearly experience the superior functional performance of Grodan growing media with respect to EC control. The generative balance in the crop should be maintained by late start & early stop times and by steering toward a stable but structurally high substrate EC. To ensure EC stability in combination with a short irrigation day ensure the irrigation session size is 4.0 - 4.5% (ml/m²) of the substrate volume (l/m²). Again your GroSens system is the perfect tool to monitor how substrate EC is developing day to day.
To get an appreciation of the uniformity of WC% and EC between the slabs the GroSens handheld system or the Reader with a GroSens sensor in ‘kit mode’ is a perfect tool. Watch the video below on how to do this correctly.
| Bright day - Vegetative steering | Dark day - Generative steering | ||||||
| Start time | 2.0 hrs after sunrise and at least 1.0 hr after opening the screen | 3.0 hrs after sunrise and at least 1.0 hr after opening the screen | |||||
| Stop time | 2.0 hrs before sunset and at least 2.0 hrs before closing the screen | 3.0 - 4.0 hrs before sunset and at least 2.0 hrs before closing the screen | |||||
| Target day level WC | 60% (Top>40%) | 55 - 60% (Top>40%) | |||||
| Target decrease WC overnight | 5 - 6% | 6 - 8% | |||||
| Moment 1st drain | Before 12:00 hrs | After 12:00 hrs | |||||
| EC drip | 3.0 - 3.2 mS/cm | 3.2 - 3.5 mS/cm | |||||
| EC slab | 3.2 - 3.8 mS/cm | 3.5 - 4.5 mS/cm | |||||
| 24 hr drain | 15 - 25% | 0 - 15% | |||||
| Irrigation volume | 250 - 350 ml/m² | 300 - 400 ml/m² | |||||
| ml/joule | Not applicable | Not applicable | |||||
| Night irrigation | If average pipe >50°C and decrease WC >8% | No | |||||
The concept of Precision Growing combines variety, climate and irrigation strategies in an optimal way. In Phase 2 work on gradually reducing the day level WC% and increasing the growing media EC until first setting.
This strategy will further enhance root penetration throughout the entire volume of the growing media. NG2.0 technology has allowed Grodan to increase the height of the growing media without loss of the slabs functional performance (uniformity of WC% and EC). The added benefit of Prestige 10 cm is an additional 25% rooting volume in the centre of the growing media (assuming like for like volumes versus 7.5 cm high slabs per m²). These roots will be more efficient than those in the bottom layer of the slab. Importantly towards the end of this phase you will require minimal irrigation volumes to stabilize and refresh the EC. Consequently ‘flushing’ the growing media is not required, thereby you are able to facilitate maximum generative steering.
Objective phase
Avoid shocks in development by retaining the right balance in fruit load and growing power in the plant for the growth of strong lateral shoots. The combination of harvest of the first fruits and new fruit setting (as the fruit load continues to increase) must be in line with assimilates supply which is variable and strongly depending on the weather.
Target crop
Growth should remain constant and uniform. The 24 hrs temperature should be adjusted to the light levels to ensure optimum partitioning of available assimilates for plant and fruit growth.
Target root zone
Root quality and activity should be retained to ensure controlled and uniform re-growth of the crop from the harvest of the fiuits on the main stem. The decrease of WC% during the night will provide a good indication for the level of plant activity during the day.
Start of phase
When the plant starts to feel the effects of the fruit load.
End of phase
Following the first harvest, when the pressure of the fruit load is starting to decrease.
During phase 2 the WC% of the slabs was lowered. Ideally by not irrigating on the dark ‘passive days’. This strategy should have resulted in complete rooting throughout the entire volume of the slab. The result is good overall crop development with increased generativity and a uniform 1st setting.
Now, at the moment of setting, daily irrigation is recommended. It should consist of 1 or 2 ‘fixed’ sessions per day. You can also begin to start working with more structured start and stop times on the basis of radiation sum. However please note that radiation sum used to trigger an irrigation is not pushed too high in the afternoon in order to allow that extra session on sunny days. High EC values in the slab (5.0 - 6.0 mS/cm) are not a problem at this time of year as long as there is no ventilation and the transpiration of the crop is at a relatively low and stable level.
A high or increasing slab EC should not be the reason to lower the irrigation EC. First create additional drain volumes. However remember not to go ‘chasing drain’ and stimulating unwanted vegetative plant development. For example on the dark days drain is not necessary or at most 10 - 15%. Drain is only desirable on the sunny days and on these occasions it may be high (in percentage terms > 50%).
The use of a fixed plastic (foil) screen can lead to large differences in climatic conditions and water absorption of the crop which will result in differences in slab WC%. Map these differences per irrigation compartment by measuring a representative number of slabs in each valve section using the GroSens HandHeld Sensor and if necessary adjust the strategy to the observed differences per compartment.
| Bright day - Vegetative steering | Dark day - Generative steering | ||||||
| Start time | +1.0 - 2.0 hrs sunrise or 60 - 100 J/cm² or 150 W/m² or WC% decrease after sunrise at 1.0 - 1.5% | +2.0 - 3.0 hrs after sunrise. When WC% decrease 1.5 - 2.0% after sunrise | |||||
| Stop time | -1.0 - 2.0 hrs before sunset Ideally leaving 100 - 180 J/cm² and a light intensity threshold 200 - 250 W/m² to sunset | -3.0 - 4.0 hrs before sunset | |||||
| Target day level WC | Stable between 60 - 70% | Stable between 55 - 65% | |||||
| Target decrease WC overnight | 8% | 8 - 10% | |||||
| Moment 1st drain | 400 J/cm² or 600 W/m² | 5.0 hrs after sunrise within 4 irrigations | |||||
| EC drip | 2.7 - 3.0 mS/cm | 3.0 - 3.3 mS/cm | |||||
| EC slab | 2.8 - 3.5 mS/cm | 3.0 - 4.0 mS/cm | |||||
| 24 hr drain | 15 - 25% | 10 - 20% | |||||
| Irrigation volume | 200 - 300 ml/m² | 200 - 300 ml/m² | |||||
| ml/joule | Only If decrease WC% >10% | No | |||||
| Night irrigation | |||||||
The growth of new roots and root tips should be encouraged by adjusting the start and stop times of irrigation, especially on darker days. The irrigation strategy and particularly the slab EC are important steering tools to maintain plant balance and fruit quality in this phase. The NG2.0 technology allows the irrigation EC to be maintained sufficiently high while the slab EC remains stable with minimal drain volumes. This makes it possible to start irrigation later and stop earlier especially on the darker days. Importantly it means that you do not have to ‘chase’ the EC of the growing media by applying additional irrigation water and creating unnecessary and unwanted vegetative crop development.
Objective phase
Realise controlled and uniform re-growth of the crop for smooth transistion to harvesting fruit on the lateral stems.
Target crop
Prepare the crop for summer creating the right balance as the plant load and production continue to increase.
Target root zone
To support increasing transpiration levels the root zone environment needs to be prepared. The recommended WC% and EC levels for maximum production.
Start of phase
Following the first harvest, when the pressure of the fruit load is starting to decrease.
End of phase
When production levels are stable.
First harvests have now been taken and solar radiation is increasing rapidly towards the longest day. From now on the irrigation strategy can become more structured. Remember there are 4 key irrigation stages during the day: Period 1: Start time after sunrise - on Joules for a sunny day or delayed on (max rest) time for a dark day.
| Bright day - Vegetative steering | Dark day - Generative steering | ||||||
| Start time | +1.0 - 2.0 hrs sunrise or 60-100 J/cm² or 150 W/m² or WC% decrease after sunrise at 1.0 - 1.5% | +2.0 - 3.0 hrs after sunrise. When WC% decrease >1.5 - 2.0% | |||||
| Stop time | -1.0 - 2.0 hrs before sunset Ideally leaving 100 - 180 J/cm² and a light intensity threshold 200 - 250 W/m² to sunset | -3.0 - 4.0 hrs before sunset | |||||
| Target day level WC | Gradually increasing to above 70% | Gradually increasing to above 70% | |||||
| Target decrease WC overnight | 8% | 8 - 10% | |||||
| Moment 1st drain | 400 J/cm² or 600 W/m² | 5.0 hrs after sunrise or within 4 irrigations | |||||
| EC drip | 2.7 - 3.0 mS/cm | 3.0 - 3.3 mS/cm | |||||
| EC slab | 2.8 - 3.5 mS/cm | 3.0 - 4.0 mS/cm | |||||
| 24 hr drain | 20 - 30% | 15 - 20% | |||||
| Irrigation volume | 200 - 300 ml/m² | 250 - 350 ml/m² | |||||
| ml/joule | 2.8 - 3.2 ml/J | 2.8 - 3.0 ml/J | |||||
| Night irrigation | If decrease WC% >10% | No | |||||
Steering the root zone between dark and bright days will encourage the crop to grow optimally for maximum production and quality. The excellent re-saturation characteristics of Prestige 10 cm allow the start time of irrigation to be timed in line with plant activity especially on darker days. Thanks to the use of NG2.0 fibre technology EC control is made very easy, even with minimal drain volumes and a relative short period of irrigation. This will help protect root quality as regrowth of the crop continues following the first harvests. In this phase the irrigation strategy becomes more structured. On bright days the start time of irrigation should be related to light sum (J/cm²) and/or light intensity (W/m²). This will ensure day level WC% are increased towards the levels expected for summer, but importantly they will prevent irrigation starting too soon on darker days.
Objective phase
Maintain maximum plant vigour and production potential by keeping plant and root quality in excellent health.
Target crop
Vegetative or generative steering will depend on the condition of the crop. The crop should remain strong to cope with large and extreme fluctuations in weather conditions. Maintain a constant fruit load.
Target root zone
Water uptake should match the needs of the crop for maximum cooling potential to create a good climate inside the greenhouse. Good root penetration throughout the entire volume of the growing media realised in Phase 2 will help the crop to cope with extreme weather conditions.
Start of phase
When production levels are stable.
End of phase
The last setting.
Start and stop times should coincide with plant transpiration. It is best to remove the maximum rest time setting from the first irrigation period and use a light only setting (see advice tables). The second irrigation period should contain a maximum rest time setting. Likewise the final irrigation period of the day should be based on light only starts. In this way on a dark day no starts will be given and on a bright day the starts continue (see advice table) and a stable decrease in WC% will be maintained.
The irrigation EC should remain >3.0mS (especially with radiation <600W/m²). The good irrigation efficiency of the Grodan slabs means you do not have to chase the EC of the growing media and can therefore keep irrigation under control especially in periods of changeable weather. A light reduction EC setting can be used but watch that you do not make the range too reactive, respecting the planned stop conditions.
An increasing EC at midday will have consequences for the plant's vigour and fruit quality if it is not controlled. In the morning start with larger irrigation volumes 4 - 5% of the volume of the growing media in order to get drain in time. In the afternoon shorter more frequent irrigations 3% of substrate volume will help keep slab WC% & EC stable and controlled.
The GroSens system is an excellent tool to assess if the irrigaiton strategy needs adjusting. The standard graphic on your climate computer should contain WC%, EC, radiation sum (J/cm²) and radiation intensity (W/m²). If scaled correctly it is very easy to see relationships between these data points and answer the following questions:
| Bright day - Vegetative steering | Dark day - Generative steering | ||||||
| Start time | +1.0 - 2.0 hrs sunrise or 60 - 100 J/cm² or 150 W/m² or when WC% falls 1.5 - 2.0% from sunrise | +2.0 - 3.0 hrs after sunrise. When WC% falls 1.5 - 2.0% from sunrise | |||||
| Stop time | -1.0 - 2.0 hrs before sunset ideally leaving 100 - 180 J/cm² and a light intensity threshold 200 - 250 W/m² to sunset | -3.0 - 4.0 hrs before sunset-3.0 - 4.0 hrs before sunset | |||||
| Target day level WC | 75 - 80% | 70 - 75% | |||||
| Target decrease WC overnight | 8% | 8 - 10% | |||||
| Moment 1st drain | 400 J/cm² or 600 W/m² or 4 - 6 irrigations | 5.0 hrs after sunrise or within 4 irrigations | |||||
| EC drip | 2.7 - 3.0 mS/cm | 3.0 - 3.3 mS/cm | |||||
| EC slab | 2.8 - 3.5 mS/cm | 3.0 - 4.0 mS/cm | |||||
| 24 hr drain | 20 - 30% | 15 - 20% | |||||
| Irrigation volume | 200 - 300 ml/m² | 250 - 350 ml/m² | |||||
| ml/joule | 2.8 - 3.2 ml/J | 2.8 - 3.0 ml/J | |||||
| Night irrigation | If decrease WC% >10% | No | |||||
The strong root system formed in previous phases should benefit the crop when transpiration is highest promoting strong growth and facilitating optimum production. With Prestige 10 cm you have the benefits of an increased volume of growing media (+25%) in the middle of the slab which promotes plant vigour. The NG2.0 technology will allow you to refresh the slab solution easily ensuring fruit and plant quality is maintained. The good block / slab interaction from use of Plantop blocks in combination with Prestige 10 cm maintains a uniform WC% & EC over the entire column height of the growing media. Consequently you will observe new 'pin' roots emerging continually from the block and developing into the slab enhancing plant vigour and production. The first drain on bright days should be achieved when outside light intensity reaches 600 W/m² or the light sum is 400 J/cm². This will ensure that the EC of the growing media is stabilised in time. On darker days you can use more generative steering to maintain the right balance, but only if the plant is strong enough. The irrigation efficiency of the Prestige 10 cm means you can easily refresh the EC of the growing media without excessive irrigation thereby safeguarding fruit and plant quality.
Objective phase
Keep the crop in a healthy condition and use the vigour to ensure production and quality is maintained right through to the last planned harvest date.
Target crop
Maintain strength and growing power of the plant and limit the ingress of disease in the crop as the light levels diminish towards final harvest.
Target root zone
Maintain a healthy and active root system and to keep the correct nutrient balance in the root zone. Ensure the irrigation strategy compensates for the rapidly changing transpiration levels. Maintain a stable and sufficient decrease WC% during night.
Start of phase
The last setting.
End of phase
When final harvest has taken place.
In order to keep the root system healthy good oxygen penetration is important. Therefore lower the irrigation frequency and the day level slab WC% will decrease slowly. To compensate for the lower irigation frequency increase the size of the irrigation volume per cylcle. Ensure the start and stop times coincide with the astronomical clock and gardually lower the day level slab WC%.
Pay attention to dark days with relatively high temperatures as the crop can evaporate more than the anticipated set radiation sum. On a sunny autumn day, the crop will only become active at +/- 100 J/cm². This is the moment for the 1st irrigation.
Often too much irrigation is given on dark days. The advice is to irrigate with minimum volumes on days >500 J/cm² and it is neither uncommon nor detrimental to the crop to achieve zero drain and the let the growing media EC increase. On days where the radiation sum exceeds 1000 J/cm² irrigation should be applied 2.5 to 3.0 times the radiation sum. Such days are appropriate for leveling slab EC between 11:00 – 13:00 hrs.
Stop irrigation on dark days up to 3.0 - 4.0 hours before sunset and target a steady decline in slab WC% overnight between 7 - 8%. Overall keep the irrigation EC >3.0 mS/cm especially when radiation <600 W/m² and consider the need for light reduction EC if these settings have been very reactive during phase 5.
| Bright day - Vegetative steering | Dark day - Generative steering | ||||||
| Start time | +1.0-2.0 hrs sunrise or 80-100 J/cm² or 150 W/m² or when WC% falls 1.5 - 2.0% from sunrise | +2.0-3.0 hrs after sunrise. When WC% falls 1.5 - 2.0% from sunrise | |||||
| Stop time | -1.0 - 2.0 hrs before sunset ideally leaving 100 - 180 J/cm² and a light intensity threshold 200 - 250 W/m² to sunset | -3.0 - 4.0 hrs before sunset | |||||
| Target day level WC | Gradually decreasing from 75 - 80% (start of phase) to 60 - 65% (end of phase | Gradually decreasing from 75 - 80% (start of phase) to 60% (end of phase) | |||||
| Target decrease WC overnight | >8% | >10% | |||||
| Moment 1st drain | 400 J/cm² or 600 W/m² or 4-6 irrigations | 5.0 hrs after sunrise or within 4 irrigations | |||||
| EC drip | 2.7 - 3.0 mS/cm | 3.0 - 3.3 mS/cm | |||||
| EC slab | 3.0 - 3.5 mS/cm | 3.5 - 4.5 mS/cm | |||||
| 24 hr drain | 15 - 25% | 10 - 15% | |||||
| Irrigation volume | In the morning 250-350 ml/m² In the afternoon 200 - 300 ml/m² | 250- 350 ml/m² | |||||
| ml/joule | 2.8 - 3.2 ml/J | 2.5 - 3.0 ml/J | |||||
| Night irrigation | No | No | |||||
The steering possibilities in Prestige 10 cm allow the day level WC% to be lowered as the outside climate becomes increasingly vegetative. A stable decrease in WC% during the night is most important. On the darker days targeting a larger decrease in WC% will help protect root quality and keep the right generative balance in the crop. The fast re-saturation properties of Prestige 10 cm will mean day level WC% can be easily increased to ensure enough water and nutrition is supplied to the heads of the crop on the bright days. Importantly when daily irrigation volumes are reduced as the day length shortens EC stability can be realized due to NG2.0 technology. Consequently ‘flushing’ is not required as the substrate EC will remain sufficiently stable (but structurally higher) thereby facilitating maximum generative steering.
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