I found a very helpful link the other day from the folks over at The Frelinghusen Arboretum in New Jersey about cutting and forcing branches to bloom in the late winter. I have seen many very informative articles, like this one from Fine Gardening Magazine, but the arboretum’s is a standout. It lists the shrub or tree, its usual bloom date and the number of days it will take to come into bloom inside your house based on the date you cut it outside. Once you look at the chart you will see what I mean, (it is far more clear than that lousy expanation I just wrote).
I use my own system here…it goes like this.
Most spring flowering shrubs need a cold dormancy period of about 6 weeks before you can cut them for forcing. I pretty much like all the seasons here for a short while , but then quickly tire of being too hot, too cold, too gray, or too sick of dirty snow. About the time I am feeling quite sick of winter, I know it is time to go cut some forsythia for forcing. Forsythia is one of the earliest and most reliable of shrubs for indoor bloom. A few weeks after the forsythia has bloomed and is starting to shatter and messing up my table, it is time to cut cherry and pear branches, followed by redbud and lilac (which is usually a fail for me.)
That , I know is very unscientific, but it works for me. But this chart is a positively a wonder. If I had a specific event I wanted to have flowers for in the spring, I could actually PLAN what I was forcing …wow. That would be pretty impressive. The chart is obviously based on the NJ USDA hardiness zone, but I know approximately when things come into bloom here so could modify it for my zone.
Off topic, and speaking of zone, the USDA working in tandem with many reputable plant people , has come up with a new weather zone map and it is very interesting. Take a look at what changes may have come to your area by using their new zip code feature. According to the new map , Jefferson went from 5b to 6a, but I will still always plant like we were zone 4 because fo our elevation and unpredictable snow cover.
Back to branches……in our new hardiness zone this year things have indeed been mild and so I cut forsythia and the buds were already starting to swell . They will open much quicker than the chart says given how unseasonably warm it has been here. I also cut some of my favorite viburnum, burkwoodii, whose blossoms have the most heavenly scent and I would be ectastic if I could enjoy them more than once a year. Viburnum is difficult to force, but given the mild temps and using the arboretums suggestion of tenting around them with a ziploc to provide humidity , the buds are definitely opening!!!! Keeping my fingers crossed