Hydrangea in Tbilisi — Why It Won't Flower, Why It Turned Pink, and How to Care for It

Hydrangea is one of the most commonly planted ornamental shrubs in Tbilisi yards — and one of the most common sources of disappointment. The questions that reach us almost always reduce to two: "I planted it three years ago, the foliage is healthy, but it never flowers," and "I bought a blue one and it turned pink the second year." Both have concrete explanations, and both trace directly back to Tbilisi's soil and climate.

First, find out which hydrangea you have

Three genuinely different plants are sold here under one name, and their care rules contradict each other:

• Bigleaf hydrangea (Hydrangea macrophylla) — round, ball-shaped flower heads, large glossy leaves. It sets its flower buds the previous summer.
• Panicle hydrangea (Hydrangea paniculata) — elongated, cone-shaped heads, white ageing to pink. Flowers on the current season's new growth.
• Smooth hydrangea (Hydrangea arborescens) — loose white globes; the best-known variety is "Annabelle". Also flowers on new growth.

If you don't know which one you have, wait for the bloom: a round ball in June means bigleaf; a cone in July–August means panicle. This distinction is the single most important thing to take from this article.

Why it doesn't flower: two causes, both fixable

Wrong pruning. A bigleaf hydrangea has already formed next year's flower buds by late summer, on the shoots that grew this year. If you cut the bush back hard in spring to "tidy it up," you are cutting off next season's flowers. Such a bush looks healthy and densely leafed and gives you nothing, year after year. Instead: on bigleaf, remove only spent flower heads and dead wood after flowering; prune panicle and smooth hydrangeas hard in spring, because they flower on new growth. The general logic is covered in our guide to pruning trees and shrubs.

Late spring frost. Winters in Tbilisi are relatively mild, and bigleaf hydrangea buds often begin swelling by late February. A frost returning in late March or early April kills exactly those swollen buds — the shrub survives and leafs out, but gives no flowers. The simplest protection is placement: don't plant against a south-facing wall, where the February sun wakes the plant too early.

Why it's pink and not blue

Hydrangea colour is governed by soil acidity and the availability of aluminium:

• In acid soil, below roughly 5.5, aluminium is available to the plant and the flowers turn blue
• Above 6.5 the aluminium is locked up and the flowers come out pink or cherry-red

Garden soils in and around Tbilisi are largely calcareous, and acidity sits above 7. That is why an imported blue seedling, grown in a specially prepared substrate, reliably turns pink in its second year in a Tbilisi yard — it is neither a defect nor the seller's fault. Keeping it blue is possible but ongoing work: an acidic planting mix, regular aluminium sulphate, and collected rainwater instead of hard tap water. Without the appetite for that, it is far simpler to choose a white or pink variety from the start. And your soil's actual acidity is established by a soil test, not by guesswork.

Yellow leaves with green veins

The same alkaline soil causes a second classic problem: iron becomes unavailable, young leaves turn yellow while the veins stay green. This is chlorosis. The quick fix is a foliar spray of chelated iron; the long-term one is mulching the root zone with pine bark or needles and switching to an acidifying fertiliser. If the whole leaf yellows, veins included, the cause is more often waterlogging at the roots than a nutrient shortage.

Watering: the real test of a Tbilisi summer

The plant's Greek name means "water vessel," which is an accurate description. In July and August, when daytime temperatures in Tbilisi push past 35 °C, a bigleaf hydrangea on a south-facing aspect wilts by midday and appears to recover on its own by evening. That is daily stress, and it ends with scorched flower heads.

Practical rules:

• Plant where there is morning sun and midday shade — an east-facing aspect is ideal
• Water infrequently but deeply, early in the morning or after sunset
• Cover the root zone with 5–7 cm of mulch — it noticeably cuts summer water use
• A drip line run around the shrub beats hose watering by a wide margin; planning details are in our automatic irrigation article

If the yard is left unattended for weeks at a time in summer, hydrangea is the wrong choice — in that case look at drought-tolerant plants instead.

September is the best month to plant

There are two planting windows for hydrangea in Tbilisi: September through early October, and late March through April. Autumn is the better one — the soil is still warm, the air has cooled, and the roots get roughly eight weeks to establish before the first frost. A shrub planted in June–August almost always suffers for it.

Planting, briefly: a hole twice the width of the root ball, compost and peat mixed into the backfill, the root collar level with the soil surface, and a generous watering immediately after planting. The rest of September's work is collected in our seasonal garden calendar for Georgia.

Get in touch

If you are planning to plant hydrangeas in Tbilisi and want the variety matched to the aspect and the soil, Dr. VERDE's seasonal agrotechnical works cover variety selection, soil preparation, and planting. If the shrubs are already in and the real problem is consistent maintenance — pruning at the right time, feeding, watering control — that is what the monthly yard care service is for.