Azalea Growing Guide

Rhododendron species and hybrids

Crop Rotation Group

Miscellaneous ●

Soil

Moist, well-drained soil enriched with plenty of compost or other organic matter, with an acidic pH below 6.0.

Position

Part shade.

Frost tolerant

Cold tolerance varies with cultivar and type of azalea grown. Evergreen azaleas are hardy to about 5°F (-15°C). Deciduous azaleas can survive winter temperatures to -20°F (-29°C).

Feeding

Boosting soil fertility results in bigger, better azalea flowers, and is especially important with reblooming varieties. Feed in spring and late summer with a shrub fertilizer blended for acid-loving plants. Keep the root zone mulched with an organic mulch year-round to keep the shallow roots moist.

Spacing

Single Plants: 2' 11" (90cm) each way (minimum)
Rows: 2' 11" (90cm) with 2' 11" (90cm) row gap (minimum)

Sow and Plant

Set out purchased plants in spring or early summer. Amend the planting hole with plenty of compost, leaf mold, or other acidic organic matter. Set the root ball high, so it is barely covered with soil. Water regularly, and cover the root zone with an organic mulch to keep the soil lightly moist at all times. Dwarf reblooming azaleas are planted 3 feet (1 m) apart, but larger varieties may need more space. Deciduous azaleas are typically grown as single specimen plants. Check plant tags for a plant’s mature width. Many dwarf azaleas can be grown in 14-inch (35 cm) pots.
Our Garden Planner can produce a personalized calendar of when to sow, plant and harvest for your area.

Notes

Evergreen azaleas become covered with beautiful blossoms in spring, and reblooming cultivars continue the show through summer and fall. Visit local display gardens to learn about the best evergreen azaleas for your area, and choose colors that match your house or other landscape features. Where winters are almost too cold for azaleas, see Rhododendron, a closely related shrub that blooms later than evergreen azaleas, yet keeps its leaves through winter in colder climates. Technically, an azalea is a type of rhododendron that blooms in spring, has funnel-shaped flowers, with stamens limited to five. Rhododendrons are larger plants that bloom in early summer, with dense flower clusters at the ends of branches, and thick, leathery leaves. A few cultivars like ‘PJM’ show characteristics of both groups. Most deciduous azaleas are woodland plants that can be difficult to get established, but are worth the extra time and trouble for the color they bring to the landscape. Many are native to North America, including pinkshell azalea (Rhododendron vaseyi) and flame azalea (R.  calendulaceum). The plants need only light pruning, which should be done after the big flush of flowers fades in summer. Most azaleas bloom only on old wood, so spring pruning removes latent buds and limits flowering.

Harvesting

Azaleas are fun to use in spring flower arrangements. The plants need only light pruning, which should be done after the big flush of flowers fades in summer. Most azaleas bloom only on old wood, so spring pruning removes latent buds and limits flowering.

Planting and Harvesting Calendar

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Pests which Affect Azalea

Aphids (General)

Slug

Snail