The greater firmness is probably the most important improvement for rose growers

Joop van den Nouweland

Grodan Vitaflor does what it promises

 “What are your requirements?,” was what rose grower Joop van den Nouweland’s substrate supplier asked him. The conversation finally led to Grodan’s Vitaflor, a firm, dry slab with a long life. And the grower experienced in the meantime that that wasn’t a vain claim. 

The past two years rose grower Joop van den Nouweland has been growing roses on the Vitaflor substrate on an area of 6 hectares at his Marjoland nursery in Waddinxveen. “What I wanted was a dry, firm slab with a long life.” Managing director Joop van den Nouweland enjoys new things, challenges and pioneering. He always has.

35 years ago he was one of the first rose growers that switched to cultivation on stone wool substrates. That proved to be a smart move. The stone wool substrate of thirty years ago is nothing like today’s top-quality high-tech substrate systems. 

Smart fibre structure

The latest arrival at the nursery is called Vitaflor, a slab with a smart fibre structure that can be used for several years. It is a product that Grodan developed specially for the cultivation of roses. So far, the Grodan Vitaflor slabs have been used in practice for only eighteen months, but that’s long enough to be able to conclude that the slab greatly outperforms other slabs in terms of firmness and water-retention capacity. “The slab is harder; it’s still as high as when we first started using it and it shows no brown discolouration whatsoever. That means that the distribution of moisture throughout the slab has been perfect for those eighteen months.” “The greater firmness is probably the most important improvement for rose growers,” says Van den Nouweland. The secret is the fibre thickness combined with the density and the way the fibre threads are connected to one another. These characteristics make the slab a bit more brittle, but also firmer. “We are now working on ways of increasing the slab’s life even further,” adds Grodan’s account manager Dennis Raadschelders. 

The fibre structure ensures good drainage of the slab. “Other favourable advantages of the Vitaflor slabs are the homogeneity between the slabs and the uniform distribution of water, nutrients and oxygen,” says the grower. The good capillary effect means that the bottom part of the slab is never too wet nor the top part too dry. The entire slab volume is available for the development of the roots, resulting in a vigorous crop. 

Moisture balance

The grower doesn’t believe that a crop’s success is solely dependent on the employed type of substrate. “Different slabs have different characteristics, and growers have to find out how to work best with them. But there’s no denying that it’s a lot easier to control the moisture balance in a ‘dry’ slab that drains quickly and sucks up water effectively like the Vitaflor slabs.”