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.
| Start time | First days during rooting in provide an irrigation every 4.0 - 5.0 hrs | ||||||
| Stop time | Not applicable | ||||||
| Target day level WC | >75% | ||||||
| Moment 1st drain | Not applicable | ||||||
| EC drip | 3.0 - 3.5 mS/cm | ||||||
| EC slab | 3.0 - 3.5 mS/cm | ||||||
| 24 hr drain | Not applicable | ||||||
| Decrease WC overnight | Not applicable | ||||||
| Night irrigation | Only at high pipe temperature (>60°C) or decrease WC block >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. To ensure good re-saturation in combination with a simple irrigation strategy throughout the duration of the cultivation you are advised to cut one drain hole per slab. However if your gutter profile is uneven you can make an additional drain hole at the lowest point of the slab. Remember with Grodan Vital it is perfectly safe to recycle the drain water from the moment the drain holes are cut.
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.
| Start time | More than +2.0 - 3.0 hrs after sunrise | ||||||
| Stop time | No later than -2.0 - 4.0 hrs before sunset | ||||||
| Target day level WC | Gradually decrease to 60% at first fruit set | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise (after 4 irrigation's | ||||||
| EC drip | 3.0 - 3.5 mS/cm | ||||||
| EC slab | 3.5 - 4.5 mS/cm (4.5 mS/cm when stimulating fruit set in low light conditions) | ||||||
| 24 hr drain | 0 - 25% | ||||||
| Decrease WC overnight | Goal > 3% relative to plant size | ||||||
| Night irrigation | Only with high pipe temperature (>60°C) | ||||||
The open fibrous structure of Grodan Vital NG2.0 facilitates rapid rooting into the growing media which is required for uniform plant development. For vegetative – generative plant balance the irrigation strategy must be in line with the climate and screening strategy. To promote optimum horizontal root formation your objective should be to gradually lower day level WC% from 80 - 85% to 60% by the time of first setting. This will help the crop fully penetrate the entire volume of the growing media providing the basis for water and nutrient uptake in the summer. This will result in stronger more vigorous plants. Accepting a higher EC range in the growing media in line with the low light levels during this phase, if applicable, will contribute towards easier 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.
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.
| Start time | +2.0 - 4.0 hrs after sunrise | ||||||
| Stop time | -2.0 - 4.0 hrs before sunset | ||||||
| Target day level WC | Gradually increasing from 60% (start of phase) to 70% (end of phase) | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise (after 4 irrigations) | ||||||
| EC drip | 2.8 - 3.2 mS/cm | ||||||
| EC slab | 3.0 - 4.0 mS/cm | ||||||
| 24 hr drain | 15 - 30% | ||||||
| Decrease WC overnight | 6 - 8% | ||||||
| Night irrigation | Normally not necessary | ||||||
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.
The warm sunny weather will accelerate crop growth and development but please be aware that the real change from vegetative to generative development comes at quite high radiation levels, (>600 W/m²) so you still need to use tools like EC and irrigation start and stop time to steer the crop towards (sufficient) generative development.
Irrigation EC should be held to at least 3.0 mS/cm. A slight decrease in set point can be programmed, especially when drain EC levels are trending upwards, but the EC decrease on radiation shouldn’t be more than 0.3 - 0.5 mS/cm².
Stop time of irrigation will vary according to the evaporation, and thus, mainly on the solar radiation at the end of the day. Irrigation should continue until radiation falls below 250 - 300 W/m², leaving 2 - 4% decrease in WC% to sunset. Irrigating too late increases the risk of vegetative crop development and a weaker root system.
| Start time | +3.0 - 4.0 hrs after sunrise | ||||||
| Stop time | -2.0 - 4.0 hrs before sunset | ||||||
| Target day level WC | Gradually increasing 70 - 75% (end of phase) | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise | ||||||
| EC drip | 2.8 - 3.2 mS/cm | ||||||
| EC slab | 3.0 - 4.0 mS/cm | ||||||
| 24 hr drain | 15 - 30% | ||||||
| Decrease WC overnight | 6 - 8% | ||||||
| Night irrigation | Not necessary in normal conditions | ||||||
Grodan Vital combines the elements of safety and security as the slab should be easy to re-saturate to 65 - 75% day level WC% in this phase. This will provide an adequate and stable water buffer which is essential for good summer production. Due to the NG2.0 fibre technology and the open fibrous structure the slab has a fast reactivity on EC in periods of variable weather it is therefore easy to maintain the target slab EC in combination with a simple irrigation strategy resulting in maximum growth and development of the crop.
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.
EC control during this phase is crucial. The GroSens sensor is an excellent tool to assess if the irrigation strategy needs adjusting. The standard graphic 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:
You can check these values with the guidance provided in the reference table.
Irrigation capacity: Insufficient irrigation capacity is the major reason for a rising EC in this phase. For adequate EC control in the growing media your irrigation capacity should be able to deliver at least 1.2 litre /m² per hour in this growing phase. You may only need this for 2 or 3 weeks of the year but in hot dry summers you’ll need it. Starting irrigation early and stopping too late, as compensation for a low irrigation capacity, achieves nothing! You will still find the computer on ‘wait ’ in the middle of the day and an increasing substrate EC will be visible on your GroSens graphic. As a result plant vigour will be lost along with valuable production in the autumn.
| Start time | +2.0 - 3.0 hrs after sunrise | ||||||
| Stop time | -2.0 - 4.0 hrs before sunset | ||||||
| Target day level WC | 70 - 75% | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise | ||||||
| EC drip | 2.8 - 3.2 mS/cm | ||||||
| EC slab | 3.0 - 4.0 mS/cm | ||||||
| 24 hr drain | 20 - 40% | ||||||
| Decrease WC overnight | 6 - 10% | ||||||
| Night irrigation | Not necessary in normal conditions | ||||||
The re-saturation properties of Grodan Vital will provide the optimum water buffer for summer production, especially on days of high radiation which demand maximum water uptake by the crop. The irrigation strategy can easily be adapted to weather conditions and plant demands resulting in a stable WC% and EC in the slab.
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.
| Start time | +2.0 - 4.0 hrs after sunrise | ||||||
| Stop time | -3.0 - 5.0 hrs before sunset | ||||||
| Target day level WC | Gradually decreasing from 70 - 75% (start of phase) to 60% (end of phase) | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise | ||||||
| EC drip | 2.8 - 3.2 mS/cm | ||||||
| EC slab | 3.3 - 4.5 mS/cm | ||||||
| 24 hr drain | 10 - 30% | ||||||
| Decrease WC overnight | 6 - 10% | ||||||
| Night irrigation | No | ||||||
A stable decrease in WC% during the night is most important to protect root quality and keep the crop in the right generative balance. The easy drain characteristics of Grodan Vital mean that EC is stabilized in the slab especially when the total irrigation volumes are reduced on the darker days. The NG2.0 technology ensures an uniform distribution WC% over the height of the slab allowing the bottom layer to dry out sufficiently overnight preserving root quality until the final harvest has been taken.
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