Shrub · Rosaceae
Grandiflora Rose
Rosa
Tall, long-stemmed, and built to bloom from spring to frost, the grandiflora gives you hybrid-tea flowers on a floribunda frame.
Full sun
Every 4–7 days
USDA 5–9
4–6 ft · 1.2–1.8 m
Overview
The grandiflora rises on tall, upright canes as one of the larger modern roses, a class bred in 1954 from a cross of hybrid tea and floribunda. Each flower opens the high-centered, shapely form of the hybrid tea, its petals furling tight at the core, while the plant carries them the floribunda way, one to a long stem or gathered into full sprays at the cane tips. Queen Elizabeth began the class, its double blooms a soft silver-pink.
The plant stands 4 to 6 feet on stiff, woody canes and keeps opening fresh flowers from May to frost. It asks for steady water at the roots and a hard cutback each late winter, and it answers with wave after wave of bloom. Set among airy, well-spaced canes, the foliage stays cleaner and the flowers come truer.
Every cane is armored with sharp, hard prickles, the thorns that make gloves and long sleeves worth wearing at pruning time. The leaves, stems, and petals hold no toxin, so the plant is safe around pets and people, and only those prickles bite.
Care
The short version: full sun for at least six hours, slightly acidic well-drained soil rich in compost, a deep morning soak at the base, a monthly feed through the growing season, and a hard cutback in late winter.
Light
Grandifloras open the most flowers in full sun, six hours or more each day, which drives buds along every cane. A little partial shade is tolerable, but dimmer light thins the bloom and leaves the foliage damp longer, which invites disease.
Water
Water deeply and on a regular schedule, ideally in the morning so the leaves dry by evening. Soak the soil at the base rather than wetting the foliage, since beads of water on the leaves are where black spot and mildew begin. Aim for even, medium moisture every 4 to 7 days.
Soil
Plant into well-drained loam, slightly acidic and rich in organic matter. A pH of 6.0 to 6.5 suits the roots, so dig in plenty of dark compost before planting and the canes root deep and grow strong.
Temperature
The woody canes are tough, weathering conditions from -20°F to 95°F (-29°C to 35°C) across their hardy range. Established plants shrug off hard cold, though a long stretch of extreme summer heat can scorch and slacken the blooms.
Humidity
Ordinary outdoor humidity suits them, so there is no number to chase. Airflow matters far more, because still, damp air trapped among crowded canes is exactly what the fungal diseases need to spread across the leaves.
Feeding
Feed monthly through spring and summer with a balanced rose fertilizer while the plant is in active growth. Ease back as the season closes, and keep the nitrogen light, since a surplus forces the soft, tender shoots that aphids and mildew settle on.
Pruning
Prune hard in late winter to early spring, cutting the bare canes back to roughly 12 to 18 inches from the ground. Take out every dead, weak, or crossing cane, then snip off spent blooms through the season to keep fresh buds forming.
Repotting
Grandifloras grow in open ground rather than pots, so repotting rarely comes up. If one lives in a container, shift it up a size when the roots circle the walls or push through the drainage holes and the blooms thin out.
Size & spacing
A mature plant stands 4 to 6 feet (122 to 183 cm) tall and spreads 2 to 3 feet (61 to 91 cm) wide. Space each one so air moves freely between the canes, the surest guard against disease creeping across the leaves.
When to plant
The grandiflora tracks the seasons on its bare winter canes. Set new plants out in early spring once hard frost has passed, or in fall where winters stay mild, then watch the first buds swell and split open in May, with fresh flowers unfurling in flush after flush until frost finally closes the season.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: early spring after the threat of hard frost, or fall in mild climates
- Harvest: May to frost
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Almost every rose trouble shows itself on the leaves and the soft, sap-filled new shoots, and most of it traces back to foliage that stays wet or canes packed too close. Read the marks and colors early, then act before they climb the plant. Match what you see below to catch it while a fix still helps.
Inky round spots ringed in yellow climbing from the lowest leaves
Those inky, round blotches with fringed edges and yellow halos are black spot, the fungus roses meet more than any other, and it settles first on the older leaves deep inside the bush. Wet foliage is what it needs, so send the morning water to the base, pick off every marked leaf, and clear the fallen ones from the ground. Thin the canes so light and air slip between them, and add a fungicide when the spots keep coming.
Fix:
- Remove and dispose of infected leaves and fallen debris
- Water at the base in the morning and keep foliage dry
- Improve air circulation by proper spacing and pruning
- Apply a labeled fungicide preventively if disease pressure is high
A chalky white dust filming the young shoots as their leaves curl
A chalky white-to-gray dust filming the upper leaf surfaces and the tenderest shoots is powdery mildew, and it takes over when warm days give way to cool, humid nights. The coated young leaves curl and warp as they try to grow. Cut away the shoots buried worst under it, open the plant to more sun and moving air, and hold back the nitrogen that keeps pushing soft new growth. A labeled fungicide or horticultural oil scrubs out a case that clings on.
Fix:
- Prune out heavily infected shoots
- Improve air circulation and sun exposure
- Avoid excess nitrogen that pushes soft growth
- Apply a labeled fungicide or horticultural oil when needed
Soft green, pink, or black insects packed onto the buds, glistening with sticky film
Those soft-bodied specks packed onto the shoot tips and buds, green or pink or black, are aphids, and the clear honeydew they leave glistens on the leaves before it blackens into sooty mold. A hard jet of water knocks the clusters loose, and insecticidal soap or horticultural oil coats and finishes the ones that cling on. Lady beetles and lacewings pick off the rest, so keep the nitrogen low and stop feeding the soft, sap-filled shoots the aphids swarm.
Fix:
- Dislodge aphids with a strong spray of water
- Apply insecticidal soap or horticultural oil to affected growth
- Encourage natural predators such as lady beetles and lacewings
Toxicity
The plant itself is gentle: true roses are non-toxic to pets and people, so a nibbled leaf or soft petal from a cat, dog, or rabbit brings no poisoning. The petals and hips are even edible. The only real hazard is mechanical, the sharp prickles armoring every cane, so handle them with care.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists true roses as non-toxic to cats, so a mouthful of soft petal or leaf brings no poisoning. The sharp, curved prickles studding the canes are the real hazard, ready to snag a curious paw or mouth.
Dogs None
Roses are safe for dogs, and chewing the green foliage causes no poisoning. The hard prickles are what to watch, since they can score the nose or paws.
Horses None
The ASPCA lists roses as non-toxic to horses, so browsing the leaves does no harm. The stiff prickles running the length of each cane may catch and tug at the lips.
Rabbits None
Rabbits can eat the leaves and soft petals safely, and many keepers pass them along as a treat. Strip the sharp prickles from any cutting first.
Livestock None
Goats, sheep, and cattle browse rose foliage with no poisoning risk. The one obstacle is the row of hard prickles armoring each cane.
Birds None
Roses hold no chemical danger for birds, and the plump hips left on the canes feed many wild species through winter.
People None
The soft petals and the hips are edible and go into teas, jams, and syrups. The prickles are the single hazard, so pull on gloves before you reach into the canes to prune.
Most grandiflora roses bear sharp thorns (prickles) on the canes that can cause scratches and puncture wounds; the hazard is mechanical, not chemical. Wear gloves and long sleeves when pruning or handling.
Varieties
Only a handful of grandifloras turn up in most gardens, set apart by the color and form of their blooms. These are the ones worth knowing by name.
Queen Elizabeth
The first grandiflora ever introduced, an upright plant of 4 to 6 feet whose double blooms open a soft silver-pink, carried both one to a stem and in long-stemmed clusters.
Gold Medal
A tall grandiflora whose golden-yellow flowers hold the high-centered hybrid-tea shape on long, straight cutting stems.
Tournament of Roses
A vigorous, disease-tolerant grandiflora that opens densely petaled coral-pink double blooms in full clusters.
Companions
Grandifloras do best beside aromatic plants that confuse pests and share their love of sun and good drainage, and worst anywhere near a black walnut.
Plant near
garlic: Aromatic alliums interplanted near roses are a traditional companion thought to help deter aphids.
lavender: Drought-tolerant, sun-loving companion that shares full-sun, well-drained conditions and attracts pollinators without crowding roots.
Keep apart
black walnut: Black walnut releases juglone, which can harm many garden plants; keep roses away from its root zone.
How to propagate
Roses can be multiplied a few different ways, though some ask far more skill than others. Here is how each method works and what to expect.
GraftingDemanding
Late summer for budding onto rootstock · One growing season
Nurseries keep named grandifloras true to type by budding, slipping a single bud of the chosen scion into the bark of a hardier, disease-resistant wild rose rootstock in late summer. The join knits and the plant establishes over a single growing season. The cut is fine and exacting, which is why it usually stays in professional hands.
Stem cuttingsModerate
Late spring through summer from semi-hardwood growth · Several weeks to a few months to root
Take cuttings from healthy current-season stems any time from late spring through summer, once the green wood has firmed and stiffened into semi-hardwood that snaps rather than bends. Roots push out over several weeks to a few months, and how readily they form depends on the cultivar. Patented varieties cannot be legally propagated.
LayeringModerate
Spring to summer while canes are flexible · One season for roots to form
While a cane is still green and supple in spring or summer, bend a low one to the ground and press a section of it into the soil. Roots grow over a season from the point where the buried wood sits against moist earth, and the rooted length can then be cut away and moved.
Myths
Roses are poisonous to cats and dogs.
The ASPCA lists true roses in the genus Rosa as non-toxic to cats, dogs, and horses, so a chewed leaf or soft petal will not poison a pet. The only real danger is a puncture from the sharp prickles. Watch for unrelated plants that borrow the rose name, like desert rose or Lenten rose, since those can be toxic.
Grandiflora is a botanical species of rose.
Grandiflora is a garden class, not a species. Breeders created it in 1954 by crossing hybrid teas with floribundas, joining the shapely, high-centered hybrid-tea bloom to the tall, clustered habit of a floribunda.