For a florist, Valentine’s Day doesn’t end at midnight.

For two consecutive hours Tuesday morning, nobody walked in to buy a flower or even to look at one in a tiny shop tucked into one of those new, brick-lined courtyards where pedestrians step off Ventura Boulevard into a bright, quiet atmosphere and feel urbane getting their hair done at St. Tropez beauty salon or sitting under Cinzano umbrellas at Le Yogurt.

The threat of rain may have contributed to the day’s slack interest in flowers, but this is what can happen after that orgiastic day of affection giving called Valentine’s Day is over. It’s kind of like a hangover for those who, without apparent premeditation, walked into flower shops and paid up to $65 for a dozen roses to be counted with those saying: “Be mine.”

It was a welcome break for florists Cathy and Helen Hasapes, two young sisters from Woodland Hills who are just entering their second year in the floral business.

“I’m just glad it’s over,” said 23-year-old Helen, the younger sister, her long gold curls bouncing.

“We had four people working in the store and five people delivering,” said Cathy, who is 27.

“My sister stayed up for two days straight,” the more talkative Helen said. “But I had a half-hour’s sleep.”

The first day they made up arrangements. That went on through the night.

“I couldn’t leave,” the more reticent Cathy said. “We only left to go downtown to get more flowers.”

“I was going to go home and change and come back,” Helen said. “And then she was going to come home.”

But by 8 a.m. the customers started coming in. Cathy had to call her sister for help. She never got a break.

“She doesn’t want this known, but she was in the same clothes for two days,” Helen said.

On Valentine’s Day, deadlines are stricter than any other day, Cathy said. The delivery deadline is midnight.

“Even on Mother’s Day a gift can be accepted a day or two late,” she said. Not a Valentine.

One customer, when told that the flowers might not arrive until late at night, told them: “That’s OK. Just as long as you deliver it that night. It doesn’t matter if it’s midnight.”

For a florist, Valentine’s Day doesn’t end at midnight.

The next day, all those men who realized how big a mistake it was to forget or ignore the tradition came in.

“We had Sunday off, thank goodness, to sleep in all day,” Helen said.

So, by Tuesday, the young entrepreneurs were grateful for the time to tidy up their store and get back to the tedium that fills a florist’s time and pocketbook between Valentine’s Day and National Secretary’s Day, on April 23, the next occasion on which tradition dictates that men should buy flowers.

They stood in the back of the shop at a small table alongside of a bar that held spools of ribbon in many sizes and colors.

Cathy worked on a large arrangement that began with a handful of Hawaiian anthuriums, which have large, round red leaves and a fuzzy stamen that stands up. The arrangement took on an impressive appearance as she added tiger lilies, freesias and tulips.

Helen, meanwhile, held a small pinching tool. Working with bundles of roses, carnations and mums, she pulled the tool over one stem at a time, scraping the foliage into a trash can.

Then she would cut the stems to length and place the flowers in small glass vases.

As they scraped, sliced and snipped the flowers, and sometimes cracked large twigs in their hands, the green juice from the leaves and stalks seeped into the lines in their hands.

“Floristry is really a dirty business,” Helen said. “I tell people if they know a florist all they have to do is look at their hands. It’s like a dancer’s feet. They get used a lot.”

When a young deliveryman appeared in the shop, Helen handed him a box of vases. He carried them across the courtyard and through a glass door leading to an underground parking lot.

“We’re doing bud vases,” Helen said. “We do about 45 bud vases every week.”

Bud vases hold those small floral arrangements that restaurants buy to give their tables an elegant touch.

They are also used to brighten up the the gray interior world of Ventura Boulevard’s high-rise offices, the sisters said.

That’s the trade the sisters had in mind when they opened their tiny, New York-style shop in a busy commercial district.

“It makes for a nice, pleasant atmosphere,” Cathy said. “We have a lot of people who come in to sweeten up each other’s day.”

“We have little office romances, too,” Helen said.

“That’s not something common, though,” Cathy corrected. “Mostly it’s birthdays and anniversaries and business things.”

As they worked, a woman in a purple suit walked in. She wasn’t buying. But she wrote a check for $96 to pay her account.

After she left, Cathy said the woman worked at a bank and bought a bud vase for herself one day. Her boss liked it. Now she buys flowers for both of them.

Helen took a break from the table to make a telephone call.

“We delivered an arrangement Saturday to Santa Monica Hospital but the person checked out the day before,” she said. “I’m trying to find the home address so we can deliver it there.”

After nearly an hour, Cathy finished off her arrangement with daisies and then boughs of myrtle and forsythia.

It was a stately three feet tall.

In a few minutes the deliveryman returned and took it away.

“It’s a sympathy arrangement,” Cathy said.