Up, Down, and All Around
“Up, Down, All Around”
We get asked often about what fertilizer works best for irises. The 3 sequence number on the bag of fertilizer will help you understand that bag’s formulation. As an example, for a bag that lists 6-8-10, the 6 is Nitrogen which helps establish lush green growth “UP” above the ground. The number 8 is for Phosphorus which works “DOWN” below the ground by strengthening roots & for irises helps them generate flowers. The 10 is for Potassium which is important for overall plant health – or ALL AROUND.
For irises, we want to use a fertilizer that has Nitrogen as the lowest number, because high nitrogen will stimulate the iris to put out more green leaves. (Note that if growing leafy vegetables one would want a high Nitrogen number!) But for growing irises, we don’t need oodles & oodles of iris leaves to one bloom stock!
We look for the highest Phosphorus number we can find (hopefully 10) as we want the iris roots to grow strong, which will allow the plant to grow good blooms.
Regarding Potassium, we look for any number that is higher than the Nitrogen number!
For the past few years we have been using a 6-10-10 formula and have really liked the results. We put a healthy pinch of 6-10-10 fertilizer in the hole of every rhizome we plant, to help establish good root growth. One place to look for is Schreiner’s who have developed their own 6-10-10 fertilizer.
Remember: Up, Down, All Around!
Happy Iris Growing!
