Irrigation is one of the key factors

Growing young vegetable plants is and remains a specialist branch in the greenhouse horticulture sector. Growers set high standards for their vegetable plants and the bar is raised every year. The start is crucial for every crop in the horticulture sector and a correct start requires a suitable product, such as Grodan’s Plantop block, says Thomas Peters, international cultivation specialist at Grodan.

Thomas Peters has extensive experience in growing different horticultural crops and young vegetable plants. At Grodan, he is giving support to propagators all over the world. This gives him a broad vision on cultivation in different climate zones and under changing circumstances.

With over 50 years’ experience in horticulture, Grodan has built up extensive knowledge about irrigation. Because of this knowledge, we support growers worldwide with their precision growing. Besides stonewool substrates, we also develop other solutions, such as the GroSens system and e-Gro – the software platform for data-driven Precision Growing, with which we can help growers and propagators to take their crop to the next level based on data.

Irrigating is a key factor

Irrigating is one of the key factors when growing plants. The cultivation specialist explains why. “During cultivation, many climatic factors can be set, such as temperature, CO₂ concentration in the greenhouse air, humidity and the level of grow lights. Sufficient water containing nutrients is a prerequisite, because one thing is certain: a plant continues to transpire.”

Propagators are continuously working on the watering strategy, 7 days a week, 24/24 hrs. “If there is no focus and mistakes are made, growers will notice this at a later stage. Examples are bad development of the truss in tomato plants, the first setting for sweet pepper plants, and/or fruit development in cucumber plants.”

It is important that sufficient moisture is present in the block because the plant continuously produces its new roots from the stem base. If insufficient water is present, this can have an impact on production. We developed the GroSens system to help growers, and also propagators, with their irrigation strategy. “Measuring is key! We all have to move away from irrigating based ‘on gut feeling’ and irrigate the plants based on facts and figures.”

Global growing

It goes without saying that, for every growing strategy and growing condition, blocks are required which have a drainage and resaturation capacity that is as high as possible, such as Grodan’s Plantop block. Its uniformity is very important. The block continues to play a role during the growing phase. Propagators have to grow plants that their customers – the growers – are asking for. Growers in different countries have different requirements.

In the Benelux region, it is fairly standard to grow with ebb and flood systems, in combination with sprinklers above the crop. In general, water supplies are organised well for propagators. Even when conditions are optimal, it is crucial to have uniform blocks for balanced intake of water and nutrients, to steer in a vegetative or generative way, in the required root/plant ratio that growers ask for.

If we look at other countries, things are quite different. “Other countries have a wide variety of systems, such as ebb and flood systems, table systems, gutter tables, cascade floors, irrigation beams, sprinklers above the crop, and hoses are still even occasionally used for irrigating. When there is such a variation in irrigating systems and growing conditions, uniform Plantop growing blocks are required.”

Tailor-made advice

The lack of a standard global irrigating system means that standard advice can’t be given. Advice has to be tailor-made. We take into account the type of irrigation system and the other growing conditions of propagators and growers do use.

In terms of irrigating, the basis is the same for all propagators worldwide: decrease the water content of the block and then resaturate it again. But every propagator – even in the Netherlands – does this in their own specific way. Grodan’s cultivation advisors provide support. “In all cases, the propagators have to fine-tune their irrigation strategy, in order to produce young plants with a plant-root quality that is as high as possible, for their customers.”