Tulip · Brussels, Brussels Capital, Belgium
When to sow tulips in Brussels
Main outdoor window
4-18 Oct
The window this page is built around.
Timed from last spring frost
13 April
In Brussels, on your chosen risk.
Ready to pick
1 Apr - 31 May
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
Step by step in Brussels
Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.
Plant the bulbs
4-18 Oct
Four to six weeks before your first frost, so roots form before the ground cools.
In flower
1 Apr - 31 May
Tulips through the year
Against the frost risk in Brussels
Why these dates
Plant four to six weeks before your first autumn frost, once the soil has cooled below about 15C - warm soil encourages the rot that hollows bulbs out over winter. Late planting is far less damaging than early; bulbs put in at the start of winter simply flower a little later. Depth matters more than date: 15cm, about three times the height of the bulb.
The bulb is hardy to around -25C once underground. Cold is the requirement rather than the risk: without twelve to fourteen weeks below 9C the stem stays short and the flower opens at ground level or not at all. In zone 9 and warmer, buy pre-chilled bulbs and treat them as annuals.
Tulips are anchored to the first autumn frost rather than the last spring one, so the planting window on this page counts backwards from the end of the season in Brussels instead of forwards from its start.
Brussels sits in zone 8b, which is milder than this crop wants, and a winter that never really arrives is its own problem. The dates below still describe the right time of year; the open question is survival rather than timing.
The median frost-free season here is 216 days, against 150 to 200 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Brussels
Other flowers to time
Growing tulips in Brussels
When should I plant tulips in Brussels?
Aim for 4-18 Oct in an average year. If you would rather not gamble on the weather, wait until 9-23 Sep - by then frost has finished in nine years out of ten.
When will tulips be ready to harvest in Brussels?
Expect to start picking around 1 Apr - 31 May, based on 150 to 200 days to maturity from the planting date calculated for this location.
How much frost will tulips tolerate?
The bulb is hardy to around -25C once underground. Cold is the requirement rather than the risk: without twelve to fourteen weeks below 9C the stem stays short and the flower opens at ground level or not at all. In zone 9 and warmer, buy pre-chilled bulbs and treat them as annuals.