Lord Baltimore hardy hibiscus

Sun

Full sun; tolerates light shade, but flowering and stem strength are usually poorer.

Water

Keep the root zone consistently moist, especially during summer. Established plants tolerate brief dry spells, but prolonged drought reduces flowering and can scorch leaves.

Soil

Rich, moisture-retentive loam or clay improved with organic matter; tolerates periodically wet soil. Avoid dry, shallow ground.

Height

4-6 ft (1.2-1.8 m)

Spread

3-4 ft (0.9-1.2 m)

Flowers

Large scarlet-red flowers from midsummer into early autumn, depending on climate. Each flower lasts about one day, with successive buds extending the display.

Foliage

Large, deeply lobed, maple-like green leaves on upright stems; deciduous.

Growth

Fast during the growing season, once the soil warms.

Care needed

Medium

• Pollinators
• Heat tolerant
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   3 ft (0.92 m)

3. After 2 years

   5 ft (1.5 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Growth rate

Fast

• Water deeply whenever the soil starts to dry; do not let a newly planted crown dry out.
• Apply compost around the plant in spring and a balanced, slow-release fertiliser if growth is weak.
• Mulch with 2-3 in (5-8 cm) of organic material, keeping it clear of the crown.
• Stake early in exposed gardens before the tall stems become heavy with flowers.
• Mark the crown over winter so you do not dig into it before its late spring emergence.

Pruning. In late winter or early spring, cut dead stems back to 4-6 in (10-15 cm) above ground before new shoots develop. Remove spent flowers if you want a tidier appearance.

Late winter

Cut back the dead stems, taking care not to damage the crown.

Spring

Top-dress with compost and renew mulch; wait patiently for shoots as the soil warms.

Late spring

Plant container-grown specimens after hard frosts and install supports in windy positions.

Summer

Water deeply during dry weather and check young shoots and flower buds for aphids.

Late summer

Remove spent flowers if desired and maintain moisture while buds continue opening.

Late autumn

Mark the dormant crown and leave the dead stems standing until late winter if they remain upright.

• Place toward the back of a sunny mixed border, where lower plants hide its bare stem bases.
• Use beside a pond or rain garden on moist ground that does not remain deeply submerged.
• Combine with ornamental grasses for contrast between broad leaves, large flowers and fine foliage.
• Repeat in a hot-coloured border with orange, yellow and purple summer-flowering perennials.

Garden styles it suits: Hot border, Cottage garden, Modern tropical, Bog garden, Pollinator garden and Southern.

Plant it with: Joe-Pye weed, Cardinal flower, Switchgrass, Black-eyed Susan, Swamp milkweed and Blue flag iris.

Wildlife: Flowers provide pollen and nectar for bees and other visiting insects; hummingbirds may visit in North America. Its hybrid origin means it should not be treated as a locally native species.

• Drought stress causes wilting, scorched edges and bud drop: water deeply and mulch to keep moisture more even.
• Aphids cluster on soft shoots and buds: wash them off with water, preserving ladybirds and other predators.
• Japanese beetles can skeletonise leaves where established in North America: hand-pick into soapy water and avoid beetle traps beside the planting.
• Hibiscus sawfly larvae can strip leaves in parts of North America: inspect leaf undersides and remove larvae promptly; caterpillar-specific Bt products will not control sawflies.

Not known to be toxic to people, cats, dogs or horses. No part of this cultivar is recognised as seriously poisonous, but it is an ornamental rather than a food plant, and eating substantial amounts may cause digestive upset.

• Scarlet rose mallow (Hibiscus coccineus)

  Usually has much narrower, finger-like leaf divisions and red flowers with more clearly separated petals; 'Lord Baltimore' has broader lobes and fuller, overlapping petals.

• Swamp rose mallow (Hibiscus moscheutos)

  Wild forms usually have broad, undivided or shallowly lobed leaves and white or pink flowers, often with a dark eye, rather than the deeply lobed foliage and scarlet flowers of 'Lord Baltimore'.

• Tropical hibiscus (Hibiscus rosa-sinensis)

  Forms a woody, usually evergreen shrub in frost-free conditions, with glossy leaves; 'Lord Baltimore' is herbaceous and dies back to its crown each winter.

Hibiscus comes from an ancient Greek name used for a mallow-like plant.

Propagation. Take softwood cuttings from new growth in late spring or early summer to preserve the cultivar. Established clumps can be divided as growth starts in spring, although the woody crown is tough to cut; seedlings will not reliably resemble 'Lord Baltimore'.

Accepted botanical name

Hibiscus

Sources: GBIF (CC BY 4.0). The care and design notes are LandscapeGPT's own.