Rhododendron 'Purple Gem'

Questions about rhododendron 'Purple Gem'

Does rhododendron 'Purple Gem' need sun or shade?

Rhododendron 'Purple Gem' grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).

It wants soil that stays evenly moist, rich in organic matter, and a good soak in dry spells.

What zones does rhododendron 'Purple Gem' grow in?

USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).

Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does rhododendron 'Purple Gem' flower in my zone?

In zone 5 it flowers late April to early May. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should rhododendron 'Purple Gem' be planted?

2½ ft (75 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 3 ft (90 cm), so a group knits into one patch.

It grows 24 in (60 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many rhododendron 'Purple Gem' plants do I need?

At 2½ ft apart, set out in staggered rows:

• 2 to fill 10 square feet (about 1 m²)
• 5 for a single row 10 ft (3 m) long
• 6 to fill a 4 × 8 ft bed on its own

In a mixed border, plant it as a group of three or five, with a second group further along in the other number.

In the bed above, the planner used one in one group.

Is rhododendron 'Purple Gem' poisonous to dogs and cats?

Yes: severe toxicity to people, dogs, cats and horses. All parts, including the nectar, are highly poisonous if eaten and can affect the heart. Even a few leaves can make a pet seriously ill.

Rated from the ASPCA. Where references disagree, the more cautious rating is used.

Is there a pet-safe plant like rhododendron 'Purple Gem'?

These come closest to doing what rhododendron 'Purple Gem' does, and no toxicity is recorded for them:

• Norway spruce 'Little Gem': the same job in a bed; 6 in shorter, grown for its leaves, not its flowers.
• Heather: the same job in a bed and the same colour; 8 in shorter, 12 in narrower.
• Deutzia 'Yuki Cherry Blossom': the same job in a bed; 4 in shorter, 10 in narrower.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

What flowers after rhododendron 'Purple Gem'?

Rhododendron 'Purple Gem' is over by early May. These start as it finishes and carry the same spot on, so it never goes flat:

• Lowbush blueberry: from early May to late May, 16 in tall, to stand in front of it and cover its fading stems (a recorded partner).
• Lady's mantle: from late May to early July, 18 in tall, to stand in front of it and cover its fading stems.
• Catmint 'Walker's Low': from mid May to mid September, 24 in tall.

What does rhododendron 'Purple Gem' look like in winter?

Rhododendron 'Purple Gem' keeps its blue-green leaves all winter, so it is one of the plants that hold a bed together from November to March, when the perennials have gone.