Forcing branches of flowering shrubs and trees is a skill I try to get better at every year–it’s another way to hurry spring up. Compared to last year, this winter has been more consistently snowy and cold. It hasn’t been severely cold, but we haven’t had the intermittent thaws that we had last year.
But for the last week, the temperatures have moderated. Almost every day has managed to get above freezing, which makes me think it’s time to start forcing branches.
How do you force branches?
The basic concept is simple: cut branches of flowering shrubs and trees, bring them into the house, and let the warmer indoor temperatures coax the branches into early bloom. But the devil is in the details!
When do you cut the branches?
Most articles about this topic say as long as you’ve had at least 8 weeks of temperatures under 40°F (4.4°C), you can cut branches anytime. Most articles also say wait for a day when the temperature is above freezing. In my cold climate, I prefer to wait until we’ve had a week of temperatures above freezing–ideally 40°F or above. That’s because those flower buds have been chilled for months (not weeks) and I like them to get a hint of spring in their system before I bring them indoors.
Other people say if you soak the entire length of the branches in water for 24 hours, it will overcome the effects of a prolonged cold season. The only place suggested for this soaking is a bathtub. Maybe you have a bathtub to spare, but I don’t want to risk finding out what happens if I put a “bunch of sticks” in the tub where family members get ready to go to work. So, I wait until we’ve had a thaw before going out to cut.
Most articles on this topic that I’ve read assume a shorter winter than what I have. This schedule from the Vermont Cooperative Extension is more realistic for cold climates, but even they suggest to start cutting earlier than I do. Experiment to see what works best for you.
What kind of branches do you cut?
Any early-blooming or -budding woody plant is fair game. It depends on what is growing in your garden. It helps if it needs pruning anyway.
Forsythia is my first choice. It blooms readily indoors; it usually needs thinning; and I love that sunshine yellow. Since it blooms so early outdoors it’s not that far from blooming when you bring it indoors. The trick is to make sure you are trying to force branches that have flower buds on them.
In my experience, the newest growth only has leaves. You want branches that are at least two years old. If you look closely at a branch, you will see two different kinds of buds. The plumper ones are the flower buds. In the photo above, you can see they are already starting to open. The leaf buds are narrower and have scales.
Of course you want to cut branches that have lots of flower buds, but also need to come out for aesthetic reasons. But the old branches that need to be pruned out are typically not the ones with lots of flowers, so choices must be made.
I’ve also forced flowering quince. The first year I tried, the branches never bloomed. The buds swelled, but never got any further than that. Eventually they started to brown and drop off, and the branches started to leaf out.
I decided I had cut them too soon, so last year I waited longer before I cut them. As with the forsythia, I cut branches that needed to be pruned anyway. In this case, the branches were hanging over a parking area, so they were not the oldest branches and had lots of flower buds. I was surprised to see the flower color was much paler than usual, and I actually liked it better.
My February daphne (Daphne mezereum) has not really grown big yet, and normally I wouldn’t consider cutting branches. But I wanted to limb it up so I could plant primroses and bulbocodiums at its base. Of course I forced the branches.
Other plants (which I haven’t tried myself) include Cornelian cherry, witch hazel (spring blooming types), poplar, willow, red maple, alder, Juneberry, apple and crabapple, birch, and cherry. Again, start with what you have, or what a neighbor gives you permission to cut.
If you followed good pruning practices, you will probably have cut larger branches with many side branches. Before going back inside, look everything over to see if you can make further cuts so you are bringing smaller branches with the most flower buds into the house.
What do you do after you cut them?
You treat them like any other cut flower, but you have to wait longer for the pay off.
- Use clean water and a clean vase. Choose a vase that is large enough to hold the branches and won’t tip over.
- Cut the ends of the branches under water, making two cuts perpendicular to each other (like a cross) so that you increase the surface area available for water uptake.
- Place in a cool room away from direct sun. And wait. It typically takes a couple of weeks, but could take longer if the buds aren’t very advanced.
- Replace the water every couple of days or whenever you see it get cloudy.
- When the buds start to open, pat yourself on the back! You can bring the arrangement into a warmer room (so you can see them as you go about your daily tasks) but they will deteriorate more quickly if you do.
A few last words . . .
The best way to get started is to stick whatever you’ve just pruned into a bucket or vase of water and see what happens. As you can see from the list above, even trees that you might not think of as “flowering” can provide some interest. The worst that can happen is . . . nothing. A bunch of sticks in water remains nothing more than a bunch of sticks in water.
But even if they don’t flower, your prunings may leaf out, weeks before they would do so outside. It’s a little bit of spring indoors and it can be addicting. Before you know it, you’ll be eyeing your garden for what else you can cut, and choosing new woodies for your garden based on how easily they can be forced. I planted a variety of willows known for attractive catkins last year for just this reason.
Want to learn more?
These websites inspired and encouraged me.