Hydrangea Growing Guide

Planting

• Plant in spring or early fall, in a spot with morning sun and afternoon shade in warmer regions, or more sun further north
• Amend soil with compost at planting time; hydrangeas prefer rich, moisture-retentive but well-drained soil
• Space plants according to mature size — most varieties need 3–6 feet to reach full width without crowding
• Water deeply after planting and keep soil consistently moist through the first growing season while roots establish

Watering & feeding

• Hydrangeas have large leaves that lose moisture quickly and wilt visibly as an early drought signal — check soil before assuming disease
• Water deeply 1–2 times per week during dry spells rather than shallow, frequent watering
• Mulch around the base to conserve soil moisture and moderate root temperature
• Feed once in early spring with a balanced fertilizer; over-fertilizing produces excess leaf growth at the expense of blooms

Pruning: old wood vs. new wood

• Bigleaf (H. macrophylla) and oakleaf hydrangeas bloom on old wood — buds for next year's flowers form in late summer on the current season's stems, so pruning in fall, winter, or spring cuts off next year's blooms
• Panicle (H. paniculata) and smooth (H. arborescens, e.g. 'Annabelle') hydrangeas bloom on new wood — they can be pruned in late winter or early spring without sacrificing that year's flowers
• If unsure which type you have, prune lightly right after flowering and only remove dead or damaged wood otherwise until you've identified the variety
• A hard late-winter pruning is the single most common reason an old-wood hydrangea produces no flowers the following summer

Soil pH & bloom colour

• Only bigleaf hydrangeas (H. macrophylla) change colour based on soil pH — white varieties and other species stay their natural colour regardless
• Acidic soil (pH below 6) produces blue blooms; alkaline soil (pH above 7) produces pink blooms, both driven by aluminum availability in the soil
• To shift toward blue, apply aluminum sulfate or garden sulfur to lower pH; to shift toward pink, apply garden lime to raise it
• Colour changes take a full season or more to show, and results can vary since soil chemistry doesn't change overnight

Common problems

• No blooms: usually incorrect pruning timing on an old-wood variety, or winter dieback of buds in a cold, exposed location
• Wilting on hot afternoons even with moist soil: normal for large-leaved varieties in heat — check again in the evening before watering more
• Powdery mildew on leaves: improve air circulation and avoid overhead watering late in the day
• Winter bud damage: in colder zones, choose reblooming or panicle varieties, or protect old-wood types with mulch and a burlap wrap

Frequently asked questions