A good irrigation strategy is very important in the early growth stage of a crop. Too much water can weaken plants, while too little water limits root growth. Thom van Wesel, application specialist at Cultilene, explains how weighing blocks daily helps improve irrigation strategies and strengthens plants.

Insights through daily weighing

Measuring helps you make better decisions. This is also true when creating an effective irrigation strategy. Many growers still rely on their instincts. While experience is valuable, having exact numbers gives you more control. The only way to get these numbers, is by weighing your blocks daily.

How do you weigh the blocks? Choose a fixed moment each day to weigh the pots, preferably within an hour after the day start. For most growers this means somewhere between 6:30 and 7:30 in the morning. Weighing them at the same time each day gives you insight into how much water evaporates. It also allows you to calculate when the critical threshold for irrigation will be reached.

Always weigh the pots in the second row from the aisle’s edge. Plants in the middle rows are often the wettest because water stays there longer. Plants in the outer rows are usually drier because they get more sunlight and air movement, causing higher evaporation and thus water uptake. By weighing pots in the second row, you get a representative picture of the conditions in the whole greenhouse.

The benefits of weighing pots

Weighing pots helps you determine when the next round of watering is needed. By knowing how much weight the blocks lose between measurements, you can calculate when to irrigate again to stay above the set minimum. The exact minimum value depends on the size and volume of the blocks you use. If you could use some help calculating this, please feel free to get in touch. 

In addition to gaining more insight, weighing also improves teamwork. A scale provides objective results, unlike estimating by hand, which can vary from person to person. This makes communication and handovers within your team more straightforward and supports clear decision-making across the company.

Beyond internal communication, weighing also improves external transparency. If a customer asks about the irrigation strategy for their batch, you can provide clear records of what happened during the growing process. This can be especially helpful when addressing questions or resolving complaints.

Ensuring the right moisture for transport

Accurate weight data is also critical when transporting plants. Before delivery, plants need to have the right moisture level. What this level is depends on how long the plants will be in transit and how soon the grower will place a dripper in the cube after arrival.

If plants are too dry, they may wilt or even die before reaching the slabs. If they are too wet, transport can lead to cell damage, increase the risk of disease and weaken the plants.

Don’t forget to measure EC values

In addition to weight, it’s wise to record the EC value. In summer, measure the EC three to four hours after watering; in winter, wait 24 hours. Since plants lose water more quickly in summer, these timings help ensure consistent and comparable data across seasons.

The EC value should be adjusted according to the plant’s growth phase. Young plants require a lower EC to support early development. As the crop matures, the EC can be gradually increased to match its growing needs. Exact target values will depend on your crop, greenhouse conditions and company preferences.

Be sure to keep track of your EC measurements, for example by using a spreadsheet. This helps you monitor trends over several days or weeks and makes it easier to adjust your nutrient strategy. If the EC is above your target value, reduce the nutrient concentration in the next irrigation round. If it’s too low, increase the concentration accordingly.

Improve your irrigation strategy

Daily weighing and recording EC after watering is an easy but effective way to improve your irrigation strategy. It helps you grow better plants, plan irrigation more effectively, and improve knowledge transfer between cultivation experts and coworkers. 

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.