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 substrate several centimeters and water absorption is no longer dependent on the moisture content in the block.
Objective phase
Fast and uniform rooting in, so that the roots are penetrating the growing media in line with the plant size.
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 only 1 or at most 2 irrigation sessions will be required to stimulate root penetration into the slab (applies to Plantop blocks only).
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.
In the first 3 to 4 days after planting aim at irrigating every 8-10 hours 150ml/m². With 1.5 plants per m² this should be about 100ml per plant/dripper. Every day as the roots start to enter the slab you should aim for one less dripping cycle. This will stimulate the pin roots to enter the slabs quickly and promote the continued generative development of uniform stems.
Good water management is critical for a successful crop. It starts in this growth phase.
While the screens are in place compensate for the lower water uptake by the plant by making sure the EC of the irrigation water used to saturate the slab initially and in the subsequent drip is high enough (a generative action). The crop will grow quickly be mindful of the substrate EC and increase the drip EC as required. For accurate EC control during the entire (2 or 3 crop) cultivation cycle we recommend you cut one drain hole at the lowest point in each slab. make sure this is done properly, poorly cut drain holes will have a huge impact on your ability to steer the substrate WC & EC. More than one drain hole will result in an uneven WC & EC within the slab and will also make steering (WC & EC) on irrigation session length (ml/m²) harder.
Remember the drain water from Grodan slabs can be recycled from the very start of the cultivation cycle. In the first 3 to 4 days after planting aim at irrigating every 8-10 hours 150ml/m². With 1.5 plants per m² this should be about 100ml per plant/dripper. Every day as the roots start to enter the slab you should aim for one less dripping cycle. This will stimulate the pin roots to enter the slabs quickly and promote the continued generative development of uniform stems.
It is important to set targets / goals for the root zone. Where do you want to be and by when in terms of substrate WC% & EC? In this respect the GroSens system is the ideal tool on which to base your management decisions – i.e. optimize your start time to avoid issues with cold stripe or Mycosphearella later in the cultivation.
| Start time | First days during rooting in provide an irrigation every 4.0 - 5.0 hrs | ||||||
| Stop time | Not applicable | ||||||
| Target day level WC | Slab >75%, Block >50% | ||||||
| Moment 1st drain | Not applicable | ||||||
| EC drip | 2.5 - 3.5 mS/cm | ||||||
| EC block | 3.0 - 4.5 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.
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 substrate 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.
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.
The crop is now rooted into the slab so ensure your GroSens sensor is positioned in the slab 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. This will avoid unwanted root pressure when the fruit load is temporarily low and avoid fruits being rejected due to Mycosphearella.
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.
The young cucumber crop will require a lot of nutrition until the first fruits begin to swell. On days with little radiation (or if the slab EC is lower than drip EC) the drip EC should remain high typically in the region 3.0 – 3.5 mS/cm.
A controlled EC in phase 2 will lead to uniform stem development and good fruit quality. Low nutrient levels in the root zone will lead to weak chlorotic heads, especially with as the fruit load develops on the main stem. In later phases this will lead to lower production and fruit quality.
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.
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 outside climate. In the morning the WC graph should first show a sharp decrease before irrigation can be started.
This later issue will avoid unwanted root pressure when the fruit load is temporarily low and avoid fruits being rejected due to Mycosphearella.
On sunny days the young fruits will swell during the early evening hours. Depending on outside conditions and ventilation strategy crop 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 cycle around 23:00 hrs. The young cucumber crop will require a lot of nutrition until the first fruits begin to swell. On days with little radiation (or if slab EC is lower than drip EC) the drip EC should remain high (3.0 – 3.5 mS/cm).
A controlled EC in this phase will lead to uniform stem development and good fruit quality. Low nutrient levels in the root zone will lead to weak chlorotic heads, especially with as the fruit load develops on the main stem. In later phases this will lead to lower production and fruit quality.
Information on how to position the GroSens in the slab can be found here.
| Start time | +2.0 - 3.0 hrs after sunrise | ||||||
| Stop time | -2.0 - 4.0 hrs before sunset | ||||||
| Target day level WC | Gradual decrease to 60% at first fruit swelling | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise | ||||||
| EC drip | 2.5 - 3.5 mS/cm | ||||||
| EC slab | 3.0 - 3.5 mS/cm +0.5 mS/cm using fixed energy screen | ||||||
| 24 hr drain | 10 - 25% | ||||||
| Decrease WC overnight | 6 - 8% | ||||||
| Night irrigation | Only at high pipe temperature (>60°C) or decrease WC >10% | ||||||
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 to 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 slab in line with the low light levels during this phase will contribute towards easier generative steering.
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.
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.
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 and slab EC’s 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.
| Start time | +2.0 - 3.0 hrs after sunrise | ||||||
| Stop time | -2.0 - 4.0 hrs before sunset | ||||||
| Target day level WC | Gradually increasing to 70 - 75% | ||||||
| Moment 1st drain | 4.0 - 5.0 hrs after sunrise | ||||||
| EC drip | 2.5 - 3.3 mS/cm | ||||||
| EC slab | 2.8 - 3.5 mS/cm | ||||||
| 24 hr drain | 20 - 30% | ||||||
| Decrease WC overnight | 6 - 10% | ||||||
| Night irrigation | Only at high pipe temperature (>60°C) and high fruit load | ||||||
The growth of new roots and root tips will be encouraged because Grodan Vital will not become too wet especially on darker days. The roots in the bottom layer of the slab in particular will remain healthy during this critical Phase of crop development because of the improved distribution of WC% over the height of the growng media due to NG2.0 fibre technology. The good re-saturation properties of the slab mean that on the brighter days it is easy to achieve a higher day level WC% by giving more water over a longer period. The drip and slab EC’s are also important steering tools to maintain balance and fruit quality in this phase. Due to the NG2.0 fibre technology and open structure the slab has a fast reactivity on EC. In periods of variable weather it is therefore easier to maintain the target slab EC.
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.
Objective phase
Realise controlled and uniform re-growth of the crop for smooth transistion to harvesting fruit on the lateral stems.
In this phase the increasing radiation sum and leaf area will lead to greater water uptake by the crop. Alter irrigation start and stop times accordingly. If an evening irrigation is necessary to stop the WC% dropping too far during the night, keep the irrigation volime low 150 - 200 ml/m² and aim to realise no drain.
Keep the irrigation EC sufficiently high EC. This will produce stronger flowers and better quality shoots. It is therefore better to control slab EC by ensuring sufficientl on a bright day rather than lowering the irrigatrion EC. Aim to keep the average slab EC relatively stable (within 0.5 mS/cm) to allow consistent plant development and fruit quality.
| 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 | 2.2 - 3.0 mS/cm | ||||||
| EC slab | 2.8 - 3.5 mS/cm | ||||||
| 24 hr drain | 20 - 30% | ||||||
| Decrease WC overnight | 6 - 10% | ||||||
| Night irrigation | At high fruit load and stimulating shoots if decrease WC >10% | ||||||
Grodan Vital combines the elements of safety and security as the slab should be easy to re-saturate to 70 - 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.
Target crop
Vegetative or generative steering will depend on the condition of the crop. The crop should re-main 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.
Objhective phase
Maintain maximum plant vigour and production potential by keeping plant and root quality in excellent health.
EC control during this pahse 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.
| 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 | 2.2 - 2.8 mS/cm | ||||||
| EC slab | 2.8 - 3.3 mS/cm | ||||||
| 24 hr drain | 20 - 35% | ||||||
| Decrease WC overnight | 6 - 10% | ||||||
| Night irrigation | At high fruit load and stimulating shoots if decrease WC >10% | ||||||
The re-saturation properties of Grodan Vital will provide the optimum water buffer for production during this phase of growth, 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.
Target crop
Maintain strength and growing power of the plant and limit the ingress of disease in the crop towards final harvest.
Target root zone
Maintain a healthy and active root system and to keep the correct nutrient balance in the root zone. Maintain a stable and sufficient decrease WC% during night.
Start of phase
When the end date of the first crop has been determined. As cucumbers are replanted 1 or 2 times per year this also applies to the last setting of the final replant crop.
End of phase
When the first crop is removed. When final harvest has taken place from the last replant crop.
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.
An increasing EC at midday will have consequences for the plant’s vigour and fruit quality. 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:
Each growing phase of the 6 Phase advice is of course applicable to the cucumber replant crop(s). Here are some additional points of attention to prepare the slab for the next (replant) crop:
| Start time | +2.0 - 4.0 hrs before 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 | 2.5 - 3.0 mS/cm | ||||||
| EC slab | 3.0 - 3.5 mS/cm | ||||||
| 24 hr drain | 20 - 30% | ||||||
| Decrease WC overnight | 6 - 10% | ||||||
| Night irrigation | Not necessarry under normal conditions | ||||||
The never too wet - never too dry nature of Grodan Vital will mean day level WC% can be increased to ensure enough water and nutrition is supplied to the heads of the crop on the bright days.
An increased WC% of the growing media will also ensure a good block contact for the replant crop and stimulate fast rooting in.
Due to the irrigation efficiency of Vital you will find it easy to level the EC of the growing media as the last harvest appraoches to ready the slab for the new replant crop. Following planting it will be easy to increase the (drip and) slab EC as the nutrient demand for the fast growing re-planting crop increases.
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