Achieving successful cultivation starts with a carefully considered growth strategy. The first weeks are critical as the roots develop and the first trusses form. By carefully managing irrigation, water content, EC, pH, oxygen and temperature, you can lay the foundation for healthy, productive plants. Our product and application specialist Marek Sowa, based in Central Europe, walks you through the key cultivation phases – from pre-planting to root establishment and beyond. Check out the table below, ‘Season Dynamics – Short Day Planting Tomatoes’, for an example.

Pre-planting: laying a strong foundation
Once your plants are in the greenhouse, you enter one of the most crucial and challenging periods of cultivation. This is the best time to steer the plants towards generative growth while building a strong root system.

Introduce a varied temperature strategy
Many growers opt for a constant air temperature of 19-20°C in the first few days to help the young plants acclimatise. While this can help with acclimatisation, it can also negatively affect the first truss and promote the development of leaf mass. To avoid this, we recommend introducing air temperature differentiation straight away to encourage generative growth and prevent vegetative boosts.

• Maintain a peak air temperature of 21-23°C during the day.
• Lower the air temperature to 16-17°C at night, with a pre-night drop to 13-14°C.
• Monitor your plants closely: if they are growing too fast or start stretching too quickly, reduce the average daily air temperature slightly.

Manage irrigation carefully
In this phase, the plants’ water needs are still minimal. Overwatering is a common mistake that can weaken root development. Water your plants once daily with around 100 ml per plant while they are next to the plant hole, ideally in the morning at around 10:00 am. On cloudy days, you can skip watering altogether.

If you are concerned that your plants are becoming too dry during the day, you can give extra water in the late evening. Late-night watering has a neutral effect on the plants compared with midday watering, which can boost vegetative growth.

Planting until roots establish: controlled slab drying
After the initial growth phase and once your plants are in place, the focus shifts to controlled slab drying. This phase promotes deep root penetration and ensures full root development in the slabs, laying the foundation for stress-resilient plants and optimal production.

Choose the right drying strategy
There are two strategies you can use to dry the slabs:

• Immediate cutting and controlled drying: Cut the slabs right after placing the plants and reduce the moisture content by 1 to 1.5% per day (7-10% per week). After 24 to 27 days, the moisture level should drop to 58-63%, the ideal level during development of the 4th-5th truss. After that, gradually increase the moisture content to 75% by the 6th-7th truss.
• Delayed cutting and natural drying: Place the plants on saturated slabs without cutting the slabs straight away. Allow the plants to absorb the excess water. Once the bulges in the slab foil disappear, cut the slabs and transition to the controlled drying strategy.

Monitor and observe 
Use slab scales or sensors to measure moisture levels accurately. In addition, look out for visual signals from the plants:

• In the morning, a healthy plant will have a light-coloured apex and upright leaves.
• In the evening, the leaves should be dark and slightly curled, indicating proper plant function.

Supporting truss development
In the next phase, the plant starts to develop multiple trusses. The focus now is on maintaining a balance between generative and vegetative growth while supporting the growing fruit.

Adjust irrigation to match growth
As the plants grow, their watering needs increase. On cloudy days, provide at least 100 ml of water per developed truss, and double this amount on sunny days. Finish watering at least three hours before sunset to prevent vegetative boosts.

The formula we use to calculate the watering strategy is: sum of radiation in J/cm2 x 3 = ml/m2. For example, on a dark day when the radiation sum is below 600J, you should start watering 3 hours after sunrise, and stop drip irrigating 4 to 5 hours before sunset, providing 140-150 ml per cycle, 3 to 4 times a day. 

On sunny days, start 2 hours after sunrise or when the radiation sum is 150J/cm2. Start the final cycle 3 to 4 hours before sunset. Give about 100-120 ml per cycle, with a total of 4 to 7 cycles per day. 

Please note that these amounts are guidelines. Always calculate the Dose Size Factor (DSF) specific to your crop and conditions to determine the optimal irrigation strategy. 

Optimise temperature and light
Maintain an average daily temperature of 17-18°C, with daytime peaks of 21-23°C and nighttime lows of 16-17°C. Continue using midday temperature peaks during the brightest hours (e.g. 12:00-14:00) to boost photosynthesis.

Maximising potential with RootmaXX cubes
A strong root system is key to successful cultivation, and RootmaXX cubes are designed to help you achieve this. Thanks to their unique cross-fibre structure, RootmaXX cubes allow plants to stay longer next to the plant hole before being transferred to the slabs. 

Benefits of RootmaXX:

• Maintains root quality..
• Enables the trusses to develop before transferring to the slabs.
• Enhances plant health and maximises yield potential.

The information provided by Saint-Gobain Cultilene has been compiled with great care and is intended solely as a guideline for the user. Saint-Gobain Cultilene therefore cannot guarantee any errors and no rights may be derived from the information or advice provided. The user himself is responsible for checking the accuracy and suitability of the information and advice for application. No commercial use may be made of the information and advice provided by Saint-Gobain Cultilene, in whole or in part, without the written consent of Saint-Gobain Cultilene.