If you're buying last-minute flowers for Mother's Day, you're not alone

Businessman flowers
Vincent Besnault | Photographer's Choice | Getty Images

Flowers aren't nearly as thoughtful a Mother's Day gift as they seem.

Online purchases in categories like jewelry and fashion spike in the weeks leading up to the holiday, but buyers tend to only order flowers at the last minute, accord to data from online advertising company Criteo.

Only 20 percent of mothers surveyed even want flowers, yet more than 60 percent of Americans will buy them this year, according to a recent survey by Offers.com. All those unwanted bouquets will contribute to $2.8 billion in total flower sales this Mother's Day, according to the National Retail Federation.

The surge in last-minute flower sales is great news for online retailers, which experience a 950 percent increase in flower and gift sales three days before the holiday, compared to earlier in April, according to Criteo.

Conversion rates—the number of online visitors who make a purchase—for online flower and gift sellers more than double, and online advertisers get a 5 percent boost in click-through rates.

The jump in flower sales starts to drop off the day before Mother's Day, as shoppers realize their online orders might not make it in time. At that point, they join the 75 percent of buyers who purchase their Mother's Day gifts offline, according to a recent survey by the National Retail Federation.

Jewelry buyers seem to be the most forward-thinking, buying their gifts a full 12 days before Mother's Day. Last year, jewelry sales peaked at 80 percent above baseline on April 29. Fashion and luxury goods peak six days before Mother's Day.

Both jewelry and fashion see smaller increases in conversion rates and larger jumps in ad click-through rates during their peaks—maybe because buyers have more time to shop around instead of panicking and buying the first bunch of flowers they find.