Tool
Autumn bulb planting date calculator
Count back from your first frost to find the window for planting spring bulbs and garlic.
Your result
Plant between 13 September 2027 and 4 October 2027
- First frost date
This is the window roughly 6 to 3 weeks before the first expected frost.
What this calculator does
Hardy spring bulbs and garlic need a run of cool, moist autumn weeks to grow roots before the ground freezes. Plant too early and bulbs sit in warm soil where they can rot; plant too late and they never root properly, so spring flowers come up small or not at all. This tool counts back from your first frost date to suggest a sensible window: about six weeks before for the ideal time, and three weeks before as the practical last call.
When to use it
- Deciding when to plant a bulb order that arrives in autumn.
- Checking whether it is too late to plant garlic or daffodils.
- Planning a planting weekend before the weather turns.
How to use it
- Find your first frost date. A local weather service or gardening calendar gives a typical date for your area.
- Enter it above. The tool returns a planting window.
- Aim for the middle of the window if you can, and treat the later date as the deadline.
Worked example
If your first frost usually arrives around 25 October, the window opens about 13 September and closes around 4 October. Planting tulips and garlic in that stretch gives the bulbs time to root, but not so much warmth that they start into leaf too early.
Typical planting months
| Bulb | Usual planting |
|---|---|
| Daffodil | September–November |
| Tulip | October–November |
| Allium | September–October |
| Crocus | September–October |
| Garlic | October–November |
| Lily (spring-planted) | March–April |
These are general ranges. Colder gardens plant earlier, milder ones later — the frost date accounts for that.
Limitations
- First frost is an average. A cold snap can come early, so do not leave it to the very last week.
- Soil temperature matters more than the calendar. Bulbs root best when the soil is cool but not frozen.
- Some bulbs differ. Tender summer bulbs such as dahlias are lifted, not planted, in autumn — do not use this window for them.
Frequently asked questions
Is it too late if I miss the window?
Not always. If the ground is still workable, plant anyway — bulbs usually flower a little later and smaller, then settle in. Better late than never.
Can I plant bulbs in spring?
Spring-planted spring bulbs flower poorly or not at all, because they miss the cold they need. Save bulbs you cannot plant for a potted, cool, frost-free spot.
Why plant before the first frost?
Because the bulb needs those cool weeks to grow roots before the soil freezes. The roots are what feed next spring's flower.
Related guides
Sources and research notes
Timing follows general UK horticultural guidance for spring bulbs; exact dates vary with local climate and soil.