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When to plant hyacinths in Grenoble: 25 September – 1 December

In Grenoble, hyacinth: plant from 25 September to about 1 December. For planting stock, the places nearby include La Centrale Jardinerie (garden centre, 1 km) and Paquet Jardin (garden centre, 4 km); addresses and opening hours are below.

Bulbs are best planted early in the window: late-planted bulbs may flower later or less well. Late planting works only while the soil can be dug. Mulch after planting.

The date is about two weeks before the average daily temperature here falls below 0 °C (ten years of weather): an estimate, not the day the ground freezes, and a cold spell can freeze it earlier. Sources: Iowa State University Extension, Wisconsin Horticulture Extension, UNH Extension, RHS, how the ground freezes (NRC Canada, CBD-26).

Hyacinth in Grenoble: soil, season and weather

Nights then average below 0 °C in November–March; the coldest, January, averages -5.1 °C.

Planting25 September – 1 December
First autumn frost25 October
Coldest nightsJanuary, -5.1 °C
Soil back at 1 °C in spring19 February
Daylight12:04 on 25 September
Daylight at the winter solstice8:45

The same dates in Grenoble hold for Garlic, Tulip, Daffodil and Crocus.

Hyacinth in Grenoble: depth, winter cold, pests and pets

Plant hyacinths 10 cm deep, at least 7.5 cm apart (RHS). In the ground hyacinths are fully hardy, but in containers they can be frost tender in cold winters (RHS); here winter nights average below 0 °C, so wrap the pots or move them to a sheltered spot.

In Grenoble the average daily temperature stays at 10 °C or lower for about 31 weeks a year (our estimate from ten years of monthly weather). For this bulb Wisconsin Horticulture Extension gives a cold period of 12–15 weeks at about 2–10 °C. The winter here gives that in the ground, so the bulbs need no pre-chilling.

Flowers get smaller in the years after planting: for full spikes, replace the bulbs or add a few new ones each autumn (RHS).

If squirrels are a problem, protect the bulbs with wire mesh (RHS). Hyacinths are toxic to dogs, cats and horses: intense vomiting and diarrhoea (ASPCA).

Sources: RHS, Wisconsin Horticulture Extension, ASPCA.

Hyacinth in nearby cities

Around Grenoble, Aosta is 45 days earlier and Lyon 31 days later.

CityDistanceDateDifference
Valence70 km22 October – end of December27 days later
Annecy86 km15 October – end of December20 days later
Lyon93 km26 October – end of December31 days later
Saint-Étienne108 km18 October – end of December23 days later
Geneva117 km18 October – end of December23 days later
Aosta139 km11 August – 22 October45 days earlier

Where to buy hyacinth for planting in Grenoble

Planting stock goes into the ground from 25 September to about 1 December; buy it before that. Within 15 km of Grenoble OpenStreetMap lists 17 garden centres, 4 plant nurseries, 55 markets and 19 farm shops (collected 20 October 2026).

Places: © OpenStreetMap contributors, ODbL.

Questions

When to plant hyacinths in Grenoble?

In Grenoble, hyacinth: plant from 25 September to about 1 December. Bulbs are best planted early in the window: late-planted bulbs may flower later or less well. Late planting works only while the soil can be dug. Mulch after planting.

When is the last spring frost in Grenoble?

Last spring frost around 5 May, first autumn frost around 25 October.

Other crops in Grenoble, with their dates