Size and of iris rhizomes and length/quantity roots has nothing to do with ability of the plant to bloom, it’s more a function of different varieties and time of year and overall growing conditions. East coast and mountain grown rhizomes are generally smaller overall then west coast rhizomes. Oh Lord. look at my dirty nails. I seem to sport gardeners manicure near every day that I am out in the garden!!! I hate wearing gloves.
This picture shows a rhizome of blooming size in early spring. Note, it’s only about the size of my thumb (I have smallish hands). How do you know it’s blooming size? There’s 2 ways to tell. One is to count the fan leaves, include leaf scars when counting. Most varieties will need 7-13 leaves for bloom. The other indicator of maturity is the presence of baby shoots or nubs near the top.
So to answer the question “Is bigger better” I have to offer a strong “no”.
Have you taken a walk in your garden lately?
This winter has brought us quite a few ‘firsts’ in our garden. For those readers living in the northern states, plants that are hard dormant are a fact of life. For us, however, this January was the first time in 20+ years that I have seen hard dormancy in many plant species in our USDA Zone 7 garden.
It’s a scary sight to unaccustomed eyes. On a warmish day, one may be quite tempted to pull back leaf cover and maybe even dig a little. Just a little, to check if plants are still there. Trust me, they are. Give them a little time and they will pop right back up and will thank you if you have not disturbed their roots. But even if you did dig a little, they will most likely pop right back up as soon as the sun comes out.
I couldn’t resist and dug a little in one of my beds. ALL the greenery had completely frozen and disappeared from these iris plants in January – look, they are peeking back out already.