q&a: pruning hydrangea, late planting, and more
WONDERING HOW—and when—to prune Hydrangea paniculata shrubs whose blooms are browning off now as late fall takes hold? (That’s one sprouting after a light pruning in spring, above.) Or whether you can plant grocery-store-bought garlic and get a crop next year? These are among the recent questions you’ve asked, that I answered on this week’s edition of my public-radio show.
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I ANSWERED your most popular recent questions this week on the latest edition of the radio show, with the help of my sister, memoir-writing teacher Marion Roach Smith. You can listen anywhere, anytime: Locally, in my Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) region, “A Way to Garden” airs on Robin Hood Radio’s three stations on Monday at 8:30 AM Eastern, with a rerun at 8:30 Saturdays. It is available free on iTunes, the Stitcher app, or streaming from RobinHoodRadio.com or via its RSS feed. The October 21, 2013 show can be streamed here now. Robin Hood is the smallest NPR station in the nation; our garden show marked the start of its fourth year in March, and is syndicated via PRX.
For a more detailed answer to each question, plus an extra question and answer or two, be sure to listen in. I’ve recapped the highlights below:
Q. I have some plants in my garage that still have to be planted. Is it too late? I’ve never planted this late before, but I just got too busy with my job.–Michelle in Canada (hardiness Zone 5B)
A. Yes—definitely get them in the ground, whether plunged (pots and all) or planted properly (removed from their pots first). I confess I often simply plunge things that are this late to getting in, using empty spaces in my vegetable garden and digging holes deep enough to accommodate the nursery pots, then putting a little soil over the lips as well.
Again: You can also simply plant them, unpotted, as you would at any other time. Be sure to tuck them in firmly.
Either way: Aftercare is important with the first few freezes, which tend to heave things up out of the ground—especially things that haven’t had enough time to root in well and resist the mechanical force of freezing and thawing.
So I go out and check them, and once the ground is frozen I pile on some mulch for good measure.
But definitely don’t leave them in your garage; better to give them insulation that the earth provides. Same with bulbs, by the way: Get them into the ground!
A. The trouble with planting grocery-store anything, to my mind, is two-fold:
- First, was it treated with any kind of retardant to inhibit sprouting, so it would stay “fresh” longer?
- Second, where was it grown, and is that farm’s climate and soil and so on similar to mine? (In other words: Is the supermarket variety that probably came from a farm in California really right for my Northeast garden?)
And therefore my answer is no, don’t plant supermarket garlic. Bulbs from the farmer’s market would more likely be fine on both counts, and I like to see the further designation that they have been grown organically. I either buy my “seed” garlic (the bulbs that I will divide into cloves and plant) from a local organic farmer or from a grower of certified organic “seed” garlic.
Q. Does anyone have a good suggestion for pruning Hydranga paniculata?
A helpful lawn guy pruned my shrub and this year I have tons of flowers all too close together and none able to grow to a decent size. There are too many stems. How to prune? And when? Do I take out whole branches to the main trunk?–Elayne
A. With Hydrangea paniculata, such as the so-called Pee Gee (short for paniculata ‘Grandiflora’) and ‘Tardiva’ and other panicle types, pruning requires a different thinking from blue-flowered moptop types, because paniculatas bloom on new wood.
Prune them in late winter or early spring, just before new growth begins. You can even prune in late fall, but I don’t like to do it until after winter has made its mess, in case branches are lost in storms, which would erase my earlier attempt at creating a good architecture.
They can be cut back quite hard, and still make new wood that then gets buds and blooms. Or you can skip pruning altogether, if you like. I know, that sounds counterintuitive–that you can choose to prune or skip it. They will sprout whether you prune or not, but depending what you do it will be on a smaller or larger plant, with fewer or more flower-producing stems.
Left on their own, many Hydrangea paniculata varieties would grow into small trees, with some up to 20 feet tall (10-plus feet is not uncommon).
As Elayne is experiencing: Not pruning, or pruning too little, will lead to a more twiggy, less-open plant that will produce many, smaller flowers. Generally, the harder you prune, fewer but larger blooms will be encouraged.
Where to place your cuts can be confusing. I have had specimens that I didn’t cut back enough turn to octopuses and really look a mess, and this is inclined to happen on older plants that have been cut back again and again to the same point. I’ve also cut old ones back too hard and had to suffer through some gawky recovery years.
The “secret,” if there is one: To get a good-shaped plant, you will often be pruning back to a mixture of oldest (thicker) wood and younger (last year’s) wood, and even some that’s in-between. The pruned structure will look odd, but try to think only in terms of creating a framework for emerging shoots that will then be topped with flowers. Your cuts indicate to the plant where it should (please!) sprout from. Let go of the fact that the wood you’re leaving will be of varying thicknesses.
Remember that these plants push lots of growth before blooming–like several feet or more–so they will be much bigger than the base architecture you created at pruning time. And as with any pruning project: First remove any damaged, inward-crossing or otherwise sub-standard stems—so that when you begin really shaping the plant, you know what you have to work with.
more answers to your questions!
- Investigate more Frequently Asked Questions (and answers!) at this link, on topics ranging from mulch and compost to seed starting and flower bulbs.