Vegetable · Cucurbitaceae
When to plant luffa
A vegetable for its first three weeks and a bath sponge after that. Growing it for the sponge needs a genuinely long season, which is why most temperate attempts fail.
Start seed indoors
6 weeks before
Counted from your last spring frost.
Plant out
2 weeks after
Counted from your last spring frost.
Days to maturity
120-180
From planting out to a first picking.
Those weeks become real dates once you name a place.
Timing, in frost-relative terms
Seed packets rarely give calendar dates, because a date that suits one latitude is wrong at another. They give offsets from the last spring frost instead, and those offsets are what make luffa plantable anywhere.
- Start seed indoors 6 weeks before the last frost.
- Plant out 2 weeks after the last frost.
- Expect 120–180 days to maturity, counted from planting out.
Getting the timing right
Start indoors six weeks before the last frost, which is unusually early for a cucurbit, and plant out once nights hold above 15C. Sponges need around 150 frost-free days.
Frost tolerance
Killed at 0C. Fruit left to mature for sponges must dry on the vine, so a late frost ends the crop before the fibre has set.
Classified as tender, with damage expected below 0°C (32°F)32°F (0°C).