How to prune hortensia macrophylla (mophead hydrangea): complete guide

Why is pruning macrophylla hydrangea different?

Hortensia macrophylla, also called mophead hydrangea, blooms on old wood. This is the critical point. Unlike many other flowering shrubs you can cut hard, you must be careful with these hydrangeas. Flowers form themselves in autumn on the branches that grew this year. If you cut everything back hard in spring, you immediately remove the flowers that would appear next summer.

Macrophylla hydrangeas bloom on buds laid down last year. This requires a completely different pruning schedule than new-wood types. Your work happens just after flowering (August-September), not in spring. This sounds cautious, but it is actually very efficient.

Bloom period and flower bud development

Your macrophylla hydrangea blooms mid-summer through autumn (July to October). After flowering, around late September, the plant prepares for next summer. Flower buds for next year form already in October and November on the tips of current branches. These buds overwinter outside, and next May-June they open.

This means: if you cut everything back hard in March, next summer you have no flowers. The plant will grow leaf and grow strongly, but not a single bloom. Year after year. It is like fighting yourself: your plant wants to bloom, but you are cutting off the flowers.

Correct pruning strategy: after bloom

The right time for macrophylla is after flowering, so August through October. Here is what you do:

After bloom (late August through September): Cut only the spent flower clusters off, just below the seed head. This does not stimulate the plant, but only removes dead material. You leave the rest of the branch intact so it can develop flower buds.

Remove dead wood: Look at all branches. Are there thin, weak branches that did not bloom? You can remove those entirely. Also remove crossing and tangled branches.

Thin crossing: If two branches cross or rub, remove one. But leave all strong, healthy branches standing. You are not pruning for shape - you are pruning for health.

Dealing with frost and emergency pruning

Macrophylla hydrangeas are not very frost-sensitive, but their flower buds can sometimes get frost damage. If you see in April that certain branches have turned completely black or are not leafing out, you can remove them. This is emergency pruning, not normal maintenance.

Cut only the dead parts away, down to the first healthy bud. Many branches look dead in April but leaf out in May. Be patient. In May you can immediately see which branches are really dead.

The first years after planting

New macrophylla hydrangeas (first year planted) behave differently. They take root, but have not yet built strength. In the first year after planting (July-September), you only gently remove the spent flower. Nothing more. Let the plant put all its energy into growth.

Only in the second year after planting can you prune normally.

Maintaining height

After a few years your macrophylla hydrangea gets quite large. If you want it not to grow taller, you cut the branches slightly in September back to the desired height. Not drastically back - just a small amount. The plant will still grow less tall next summer, and you keep the flowers. This is not "hard pruning" - it is "maintaining height".

Step-by-step

Step 1: Wait until after flowering

Bloom usually stops by late September. Wait until all clusters start to fade.

Step 2: Remove spent flowers

Cut the spent flower clusters off just below the seed head. You leave the rest of the branch intact.

Step 3: Remove dead wood

Look at all branches. Cut dead, weak, or crossing branches entirely away.

Step 4: Rest through winter

November through March: do not prune. Let the plant rest and develop her flower buds.

Frequently asked questions

What if my hydrangea had no flowers last year?

You may have cut it hard in spring and thereby removed the flower buds. This year: be careful. In September only remove the spent flower. Leave all branches. Next summer you will see many more flowers appear. Patience is the most important ingredient here.

Can I make my macrophylla smaller?

Yes, but carefully. In September, after bloom, cut the whole plant back to the desired height. Not too much at once - maximum one third of total height per year. This happens only once, not annually. The plant will stay small because you always cut after bloom.

Does my hydrangea bloom less after pruning?

Only if you prune in spring. If you prune after bloom (August-September), next summer you have even more flowers because the plant can grow quietly and develop more buds. Pruning after bloom leads to more flowers.

Do I need to remove the clippings?

You can leave the spent flower clusters sitting through winter - they look nice with frost on them. Early January you can pick them off and compost them. Do not cut in October, wait until January.

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