Pick Up the Pot
More and more growers are utilizing wood-based substrates for production. Whether the mix has a small percentage of wood (10 to 20%) or a larger volume (40+%), there is a need to change the way one manages growth and irrigation.
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. 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.
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. Also determine if the irrigation frequency is reduced, that 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.
Brian Whipker
Professor, Horticulture, North Carolina State UniversityBrian E. Whipker is a professor of floriculture at North Carolina State University. He has an appointment split between extension and research, but also teaches the graduate level plant nutrition course at NC State. His specialization is plant nutrition, plant growth regulators, and problem diagnostics. He brings over 30 year of experience in diagnosing grower plant problems.
