Hydrangeas are truly a dramatic sight in the mid- to late-summer garden, thanks to their large, showy flower heads. They'll grow in anything, from full sun to shade in most areas of the U.S. Because they thrive in moist, semi-shaded areas, they make excellent foundation plantings. They can be planted individually or in mass to put on a spectacular display.
Quick Reference Planting Guide
- Location: Sun or shade.
- Hardiness Zone: Suitable for zones 3 – 8 for all except Dwarf ‘Piamina’, the Mopheads 'Harlequin', 'Parzifal', the Variegated Lace Cap, Japanese Lace Caps, and the Oakleaf Hydrangeas. These are best for zones 5 – 9. Potted plants should be moved into a protected, unheated area such as a garage over winter in northern zones. Moving them to a protected area next to a foundation, preferably on the south side of the home, will also give them the necessary protection. This will also increase the hardiness range by as much as one or two zones.
- Planting Distance: 4' apart; Dwarf ‘Piamina’: 2' – 3' apart.
- Mature Height: 3' – 5' with a similar spread within two – three years. Dwarf ‘Piamina’ grows 2' tall and 2' wide.
- Bloom Time: Early to mid-summer to frost for the first year.
- To Plant: Dig a hole twice as wide and twice as deep as the pot. Remove the plant from the pot and carefully place the root ball in the hole level with the soil surface. Refill with soil mixture. Firm the soil around the plant with your fingers. Water thoroughly.
Hydrangeas flourish in a wide range of soils, from well-drained average to wet. If you wish, you can also grow these dramatic shrubs in containers. You can improve your planting success as follows:
- Spade or rototill the soil to a depth of 12" – 18".
- Mix in a 2" – 4" layer of dehydrated manure, garden compost, shredded leaves, and/or peat moss. After active growth begins, periodically feed with water soluble plant booster. Plants in containers especially need more frequent water and feeding, especially when in active growth, bloom, or while setting fruit.
- Watering: If you plant in pots, don't let the pots dry out, especially if they're not in a sheltered spot or directly planted in the open garden. Your plant requires at least 1" of rainfall, or equivalent watering, each week when in the ground. In a container exposed to full sun, water at least once every other day. During drought or extremely hot weather, water more frequently.
- Mulching: Apply a 2" – 4" layer of shredded bark, compost, or other organic mulch around your plants to promote moisture retention, maintain even soil temperatures, and discourage weed growth.
- Weeding: Keep the area around your plants free of weeds. Weeds compete with plants for food, water, and light. Walk around the garden periodically and pull weeds, including the roots, as soon as you see them. Mulch also assists in keeping weeds down.
- Deadheading: Remove spent blossoms to promote additional blooming. Pinch or cut off when they fade, but leave as much foliage as possible.
- Grooming: Clip off unsightly or dead growth to maintain the plants in good form and shape. Cut flower stalks between the bottom blossom and the uppermost leaves.
- Feeding: Discontinue any feeding after September 1. Your plants want to harden off for winter.
- Winterizing: Once the ground is frozen, apply a winter mulch of evergreen boughs, straws, or leaves to the plant’s roots from lifting during freezing and thawing periods. If you move your containerized plant to an unheated protected area over winter, be sure to water it once every 7 – 10 days. As soon as the weather warms, remove any mulch from in-ground plantings. At the same time, be sure to prune off any dead wood.
- Containerized Plants: Move your containers to a sheltered location in northern zones such as an unheated garage or shed over the winter. You can also move containers to the south side of a foundation and mulch for the winter. Such warm locations sometimes increase the hardiness factor by two planting zones sometimes. You can also bury or plant either the plant itself or the entire container in the garden and mulch after the ground has frozen. As soon as the weather warms, remove any mulch from the container and bring it back out into the garden sunlight.
- Dividing: Daylilies will multiply over the years. Every 4 – 6 years, you can divide your daylilies and replant them to make more beds or to share with friends. Spring or early fall is the best time to divide and replant.