Now that we are on the cusp of September, I am organizing my plans for transplanting several hydrangeas. Plus I need to put in several new plants so I can trial them for a few years and report back to you on their progress.

Autumn is the best time for planting and transplanting your hydrangeas in the Northern hemisphere. Although Southern hemisphere gardeners are marching into spring, you could also do this work now.

Hydrangea serrata 'Bluebird' in full bloom

Hydrangea serrata ‘Bluebird’ in full bloom


Where I am, I need to give any new plantings enough time to settle in before the ground freezes. That usually takes about 6 weeks. So you just count backwards 6 weeks from that approximate date in your area and use that as your deadline to get the planting done. For me in Zone 5B (my ground is usually frozen by about December 1), I need to get my plants in the ground by about mid-October. Keep in mind that this is the same time big leaf and mountain hydrangeas are forming their buds for next year. So get it right and be gentle!



Do the same counting for southern hemisphere gardens, but use your last frost date (if one exists) and count forward 6 weeks. You need to give your soil a few weeks to warm up to help plant roots get better established. Your objective is to have your plants’ root systems healthy and able to support your plants as you go into summer. If you can wait until autumn to transplant your hydrangeas, your plants will fare better.



But why is it so much better to transplant hydrangeas in the fall than in spring when most of us are madly digging? Here’s the science. In fall, the ground is wonderfully warm and is just the right temperature for your plants to develop roots and get comfy. Spring planting is usually done with much colder ground so plants don’t get such a good start.

Another advantage for transplanting hydrangeas in autumn is the shorter daylight hours. The possibility of heat stress is greatly reduced. Compare that to spring daylight which is ever increasing along with the heat. As a result, heat stress is more likely then. And lastly, natural rainfall is more plentiful this time of year so the burden on you, the gardener, to irrigate is greatly reduced. Plus no irrigation set up or schedule can match the benefits of a steady and slow drip from Mother Nature.



Back to your garden…Remember those cuttings you rooted in mid-season when you “pinch pruned” your hydrangeas? Those little darlings should have developed roots by now, so go and check them.

Look closely. Specifically examine your cuttings for the emergence of new leaves at the center. They should be there by now, a sure sign that your cutting has indeed grown some roots (enough to push out new leaves!). Yes, I know they are tiny, but the clock is ticking.

Hydrangea Cutting With New Leaves

Hydrangea Cutting With New Leaves


Gently take the cutting out of the pot to verify roots are there. HOORAY!!!

Hydrangea Cutting With New Roots

Hydrangea cutting with new roots

Now you just have to get that baby into the ground so it can get established. You’ll have to remember to protect it this first winter if you live in a cold zone. Temperature fluctuations can cause new plants to heave and get their roots exposed – a sure death knell. You want to prevent that from happening. Once your ground freezes, apply lots of mulch at the base. Consider covering the new plants with a nursery pot (held with a stone). They will be protected from severe weather, and wildlife like rabbits can’t get to them.

Nursery pot being used for winter protection

Nursery pot being used for winter protection


If you had lackluster flowering on your plants this past season, it could be a cultural issue like too little sun, or stressful dry conditions. Maybe it was winterkill.

Assuming it’s not a pruning issue (transplanting can’t fix that), think about where you might move a plant to improve its cultural conditions. For me, it’s not enough sun. Surrounding vegetation has grown too big so I either transplant my hydrangea to a sunnier spot or remove/cut back the surrounding plant growth of its neighbors.



If sun isn’t your issue, maybe it was winterkill. In that case, consider how you can provide winter persistent something to better protect your hydrangeas. Can you add a plant to your garden that will shelter your hydrangea without creating root and water competition? Can you move your hydrangea so a structure like a shed, fence, or house can provide that important protection? I can’t tell you how often I have solved a hydrangea flowering issue just by transplanting.



You can also consider dividing your overgrown hydrangeas this time of year. Just dig from the outside of the plant to separate a piece that can then get planted somewhere else. Or give that piece to someone who wants to add a hydrangea to their garden. It’s a win-win. This is especially useful for your woodland hydrangeas like ‘Annabelle’ that have a tendency to sucker and create large colonies.


You may want to refer back to a earlier post I did on transplanting — it never gets old.


For a more complete discussion of transplanting and dividing hydrangeas, see the photo-heavy chapter on this topic in my best selling book, Success With Hydrangeas, A Gardener’s Guide.

Cover of best selling book "Success With Hydrangeas"

Cover of my best selling book, Success With Hydrangeas


Happy digging and thanks for reading.

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