The University of Minnesota gives us a lot of research on Horticulture. There are lots of plants and circumstances to learn.
When I was a kid my Dad would always say, “this is an unusual season”, because every year, every season was different than the previous year. Every year was a new experiment given to us by the creator on ‘how are the crops going to do this year’.
In the last three years my Iris plant went from 16 to 24 to 52 stems with blooms all from one plant. The first increase came because I had removed 20% of the plant because it had gotten too large and the research shows that pruning it will increase yield. I had done the proper thing by the book and it worked well. This past year I did almost nothing different and had huge increase in blooms. But the weather was different. We had a very early snow cover and lots of snow to insulate the soil and provide water. Because of the snow cover we had almost no frost so the snow melted straight down and soaked the subsoil and the soil temperature was very warm.
Lessons learned are that even though regular Irises are rather drought tolerant, they do need some water in a dry fall and can be soaked for a couple of weeks in the spring. Warmer soil is very good. Use extra mulch and/or scoop extra snow on the area where bulbs are in the winter. I might even use warm water in the spring because nothing ever took frost out of the ground faster than a 60 degree rain in the spring.
It is always necessary to know your variety of plant. Siberian Irises always need much more water than normal Irises. In these droughts my Siberian Irises went from 15 to 4 to 0 stems with blooms these last three years. The leaves on an Iris are like grass and they do not wilt like other garden plants so you do not necessarily notice drought stress till they quit blooming.
Roger Elgersma, Master Gardener
A University web site on watering is “Water Wisely: Start in your own backyard | UMN Extension”