The Peony Bloom Time Project
In the past peony bloom dates have been collected by many people. To my knowledge, previous to this project, there have been two major attempts at collecting/consolidating and publishing data over a large number of cultivars. To this we can add the body of information published in nursery catalogues.
The Miller Data
Rev Floyd Miller collected bloom dates for 200 cultivars at Fergus Falls, Minnesota from 1963 to 1975. The location is 140 miles West and 80 miles North of Minneapolis.
The Miller data has two strengths. The first is the use of 13 years of data. The second is the evidence on many older American lactiflora cultivars. It is unlikely that we will find new evidence on these older American cultivars. The Nichols Arboretum has many early American lactifloras but they do not have the staff to collect bloom data.
As presented on pages 191-2 of the APS, Best of 75 Years, the Miller data is a single date for each cultivar. The data is not a simple average of the actual observations but appears to be a median rather than a mean. A median date has an equal number of bloom dates before and after. It will differ from a mean, or simple average, date but probably not by more than one or two days.
Leon Presnell compiled bloom sequence data and placed it on the Heartland Peony Society web site. This is the most comprehensive list of bloom dates available. There are about 440 cultivars and 1300 observations in the Pesnell data.
Nursery catalogues provide information on the bloom time for cultivars that they sell. They all do this using variants of a classification system that designates a cultivar as an early, middle or late bloomer. Many use a more complex system that includes very early, very late and some intermediate cases such as early-middle or mid-late. Don Hollingsworth of Hollingsworth Nursery has one of the more complex systems while Klehm's Song Sparrow has a relatively simple one.
Lindsay D'Aoust of La Pivoinerie D'Aoust and I have discussed trying to create a common classification system. Personally, I favour a system with five groups or categories, VE, E, M, L and VL. A new common classification system is important because it is not likely that nurseries will ever use a system such as the Red Charm relative dates. The basic weakness of any classification scheme is that some cultivars will bloom near the boundaries of the groups.
New bloom data has been collected and organized by myself, Michael Denny from observations in 1999 to 2003. This adds about 1200 new observations. Bloom data was collected by Brian Porter, Carlos Beca, Lindsay D'Aoust, Leo Smit, Julia Dicks, Val Ames and Irene Tolomeo. I added my own data and organized the information. Some of the data are for years prior to 1999. In particular, Julia and Brian had observations over a number of prior years.
I am hoping that everyone who contributed data in the past will continue to collect bloom dates in 2011 and beyond.
Our objective is to provide reliable information on the bloom sequence of peonies. The simplest method would be to construct a ranked list of cultivars starting with the earliest bloomers and moving on to the later ones. Such a ranked list is simpler than our current methods because no information is provided about the period of time between the blooming of each cultivar.
What is Missing?
We have very limited information on the bloom times for tree peonies and for the peony species. In both cases, far fewer peony enthusiasts grow the plants. Over time, I hope that we can improve this situation.
If you are interested in contributing data to this project, I can be reached at email@example.com