Photo: Brian Whipker
With more and more growers utilizing wood-based substrates for production (whether the mix has a small percentage of wood or a larger volume), there comes a need to change the way one manages growth and irrigation.
That’s according to North Carolina State University Horticulture Professor Brian Whipker who, in a recent eGRO blog post, notes that a number of growers have talked about the need to change their irrigation practices.
“Typically, one would observe drying of the surface layer of the pot and know it is getting time to irrigate. Wood-based substrates require another step when determining the need to irrigate,” he says. “Growers are discovering that while the soil surface may be dry with a wood-based substrate that the remaining profile of the soil column often times is still saturated. This means that irrigation is not needed at that point.”
Whipker says if irrigation scheduling is based on only the dry soil surface, then overwatering is occurring.
“This has led to poor plant growth, induction of iron uptake problems due to overwatering, and also root rots,” Whipker says. “If the irrigation frequency is reduced, there may be a need in increasing the fertilizer rate used in order to provide adequate nutrients. So until you get comfortable with wood-based substrates and build your expertise, pick up the pot to gauge when irrigation is needed.”