How To Propagate Hydrangeas in Fall

Hydrangeas are classic beauties of the summertime garden, always leaving us wanting more as their season winds down. To expand the collection, it’s possible to propagate hydrangeas in the fall using a few techniques.

Propagation through cuttings is useful for creating a number of new plants, while ground layering offers an easy outdoor propagation method for larger transplants. Dividing established shrubs creates sturdy offspring for transplanting before soils freeze.

Hydrangeas are not only beautiful but also resilient and adaptable shrubs. If you have a favorite, or for economical and gardening fun, try cloning the parent plant through stem cuttings or layering. If your mature shrub is showing a dense crown with good outer growth, division is worth a go for certain species and won’t harm the existing selection.

Hydrangea Fall Propagation Guidelines

Hydrangeas are durable woody shrubs that grow and bloom across a wide range of climates and conditions. Hardy in most growing zones, they survive winter temperatures down to zone 3 and in hot summers in zone 9.

In areas with extremely cold winters, opt for panicle (H. paniculata) and smooth hydrangeas (H. arborescens) for early and long-lasting flowers. Both types bloom on new wood, which avoids winter bud damage, and they’re exceptionally cold-hardy. In warm climates with hot summers, protect hydrangeas from intense sun.

Morning sun exposure and dappled light are optimal situations. Provide regular water during the growing season, especially until established and during dry spells. Water through frost to promote turgid roots and stems heading into winter dormancy.

Cuttings are the primary way to propagate hydrangeas in fall and produce the most new plants. Aim to take cuttings or create ground layers in early to mid-fall while hydrangeas are still actively growing (though you can take hardwood cuttings later, too).

Divisions do best at least four weeks ahead of a heavy frost. This gives new transplants time to develop roots before the soil freezes. Alternatively, wait until dormancy to dig and divide. Prepare your transplant area by checking soil quality and adding compost to increase richness and aeration. Lightly turn the soil to loosen it and promote root development for new transplants.

Hydrangeas do best in organically rich, well-draining soils with medium moisture. They grow in acidic, neutral, and alkaline soils, with pH influencing bloom color except for in white cultivars.

Cuttings

To propagate hydrangeas via cuttings in fall or winter, use sharp, sterile pruners. Cuttings take the longest to grow into sizeable blooming shrubs, but it’s a way to create multiple clones of the parent plant. Hydrangea cuttings begin to grow in about four to six weeks.

How To Take Cuttings

While fresh, pliable growth is more noticeable in spring and summer, in fall, look for flexible growth that’s not overly woody. To take cuttings:

• Cut a four-to six-inch piece of healthy stem from newer growth, ideally from a stem that didn’t flower this year.
• Remove the foliage from the bottom section of the cutting, keeping one to two upper leaves intact. Cut large leaves in half to reduce moisture uptake and evaporation. Keep the cuttings moist until ready to pot.
• Optionally, moisten the cutting and generously coat the lower stem with rooting hormone. Tap off any excess rooting powder.
• Plant the cutting in at least two inches of moist, well-draining potting mix. One-half to two-thirds of the stem should be covered, including at least two leaf nodes. Hydrangeas also root in water, following the same nodal coverage without excessive submersion of the stem.
• Place the pot or tray in a bright, warm location, out of direct sunlight.
• Mist or water as needed to keep the soil evenly moist.
• When cuttings resist a gentle tug – generally two to four weeks for hydrangeas – roots are in place, and cuttings are ready to be repotted.
• Plant the cuttings in four- to six-inch pots to continue developing.

Seedling Care and Overwintering

Newly rooted cuttings in the fall need protection over the winter unless in a mild, frost-free climate. Tender roots and upper growth are susceptible to cold damage. Plan to overwinter the pots in a bright indoor location.

Water to promote evenly moist soils, but avoid oversaturation as growth slows in the cool season. Move the young plants to the garden with spring’s warming temperatures, hardening them off gradually to acclimate to outdoor conditions.

Ground Layering

Ground layering is an easy way to propagate hydrangeas in fall that uses existing branching. Layering hydrangea stems mimics a feature the plants use naturally. Low stems make contact with the soil and begin to establish roots. As roots strengthen, the offshoot becomes self-sufficient and stands alone from the parent plant. 

Prep the Stem

For the best layering branches, look for low-growing, pliable stems with healthy new growth and slightly woody bases. They need to be able to bend to the soil level. Keep the branch attached to the mother plant.

Determine a five- to six-inch portion where the stem best meets the soil, and remove any leaves around this section. Using pruners or a blade, lightly scratch and scuff the bottom of the stem in the segment. Optionally, apply rooting hormone to the scarred base to spur root development.

Dig a shallow trench, about one to two inches deep, and situate the scuffed portion in it. Cover the stem with soil. The base and end of the branch (at least six to 12 inches) remain exposed.

Peg or Weight

With the layered stem nestled in place, anchor or “peg” it to hold. A sturdy sod staple, brick, or rock on top of the soil coverage does the trick.

Leave the layer in place for six to eight weeks to develop healthy roots for transplanting. With a fall ground layer, overwintering in place is the safest option. Keep the sections evenly moist ahead of frost, taking care not to create overly wet conditions. Add extra mulch or leaves for protection in cold winter climates.

Check for root development after the one- to two-month timeframe (longer during winter). If the stem shows good rooting in early spring, clip the young plant from the mother with pruners or a sharp spade and situate it in its new garden location or pot.

Division

Bigleaf (H. macrophylla) and smooth hydrangeas (H. arborescens) are best for dividing. Panicle, climbing, and mountain hydrangeas show the best propagation with cutting or layering. The prolific hydrangea with flexible outer growth responds well to digging and transplanting. Done correctly, the mother plant won’t suffer damage from dividing outer growth.

How to Divide

There are two approaches to dividing hydrangeas. First, dig the whole plant with a spade or shovel. Lift the entire root ball for separating outer divisions. The second approach is to remove a viable outer section with a sharp spade, severing stems with roots attached, to separate into divisions.

Work with the outer perimeter to begin dividing. Younger shoots and roots separate easily from the mother plant.

For the best viability, replant the segments and the mother plant shortly after dividing. With the planting area prepped and amended, tuck the divisions into loose, well-drained, organically rich soils. Water well and mulch the new transplants, providing extra protection in cold climates.