Panicled hydrangea «Grandiflora»

Panicled hydrangea 'Grandiflora' (Hydrangea paniculata 'Grandiflora') – a cultivar of panicled hydrangea. The cultivar was discovered in 1862 by the German naturalist and explorer of Japan Philipp Franz von Siebold.

It is a deciduous shrub or small tree with a dense rounded crown. It reaches 2–2.5 m in height and up to 3 m in diameter. It grows rapidly, with an annual increase up to 25 cm. Shoots are pubescent, later glabrous, covered with reddish-brown and later brown peeling bark. Roots are superficial, located shallowly, and their spread significantly exceeds the crown diameter; the plant forms root suckers.

Leaves are elliptic or ovate with an acute tip and a broadly cuneate, less often rounded base, dark green above, densely bristly or nearly glabrous, beneath grayish-green and bristly along the veins. Leaf margins are sharply or coarsely serrate. Leaves do not have a pronounced autumn coloration.

Flowers are large sterile, broadly pyramidal panicles, 20–30 cm long. When opening they are creamy-white, later pure white, then pink; in autumn they become greenish-red. The cultivar is distinguished by later flowering.

Hardiness zone: 4 (-29°C).

Location: heat-loving; planting sites with some shade are preferred. Requires protection from strong and cold winds. Drought-resistant but prefers moist sites. Not recommended to plant next to fruit trees. Tolerates urban conditions well.

Soil: grows well on fertile slightly acidic to acidic soils; does not tolerate calcareous soils. Prefers moist, well-drained soils without waterlogging.

Planting: the optimal age for planting is 2–3 years. Planting is best done in spring or autumn. Planting hole size on light cultivated soils - 40x40x50 cm, on loamy cultivated soils - 50x50x60 cm, on heavy clay soils - 60x60x70 cm. It is recommended to place drainage such as gravel or crushed brick at the bottom of the hole in a layer of 5–10 cm. A layer of fertile soil 10–15 cm thick is placed above the drainage. Spread the roots over the entire area of the hole and position the root collar at soil level. Water consumption after planting per plant: on sandy soil 20–25 l, medium loam 15–20 l, heavy loam 10–15 l. In dry and windy weather it is recommended to spray the plant immediately after planting.

Care: it is recommended to loosen the soil around the shrub at least twice a year to a depth of up to 5 cm. Watering should be carried out at least 5 times per season. To increase stem strength you can water along the canopy and at the root with a weak potassium permanganate solution. Fertilization with manure or mineral fertilizers is carried out at the beginning of growth, during bud formation, and also 1–2 times during the summer. In winter it needs to be sheltered with spruce branches or dry leaves.

Pruning: tolerates pruning well. For abundant flowering it is recommended in spring (after bud swelling) to prune diseased shoots; in older plants shoots are cut back annually by 2/3 of their length.

Propagation: mainly by cuttings. Cuttings can be taken only in the first decade of June; select a cutting with 5–6 nodes, remove the leaves from the two lower nodes, then bury the cutting in loose, moist soil to two nodes. It is recommended to add some sand to the soil. Remaining leaves should be cut back by 2/3. After that cover the cutting with a 2- or 3-liter jar. Cuttings should be placed in shade and the soil kept constantly moist.

Pests: aphids (pelargonium, greenhouse, pea), greenhouse thrips, spittlebug, spider mite, green tree bug, berry bug, meadow bug, shiny pale leaf beetle, nettle leaf weevil, cutworms (larvae of noctuid moths), golden chafer, hairy moth, marsh crane fly, earwig, gall nematode.

Diseases: tracheomycotic wilt, white sclerotial rot, gray mold, common (European) canker, tubercular bark necrosis, powdery mildew, Phyllosticta, Septoria, ring- and Ascochyta leaf spots, chlorosis.

Companion plants: mock orange (Philadelphus), Sorbaria, rowan.

Uses: stands out attractively in standard (stem) form, especially when designing gardens in a formal style. Used in the design of ceremonial staircases. Looks magnificent when planted near houses with columns. The shrubby form is used in landscape-style gardens. Can be used for creating winter bouquets, for cutting, and in container plantings to decorate patios, verandas, and balconies.