NEW YORK -- Looking for a way to save on Mother's Day flowers? Have an arrangement delivered a day early.

It's one way to keep costs in check when using flower delivery sites such as 1-800-Flowers.com, FTD.com and Teleflora.com, where costs can quickly add up to more than you expected.

The sites nevertheless offer convenience for anyone crunched for time or unsure about putting together their own floral arrangements. And there's a reason flowers are such a popular gift -- they rarely disappoint.

It's why about two-thirds of Americans plan to buy flowers as part of their Mother's Day celebrations this year, according to the National Retail Federation. The average amount spent on the holiday is projected to be $141 this year, and the average flower expense $17.

If you don't live close to mom and are thinking about sending a bouquet, here are some last-minute tips to get the most for your money:

Size up costs

As you begin browsing floral arrangements, keep in mind that 1-800-Flowers, FTD and Teleflora all charge a service fee, which includes the cost of delivery. This will significantly increase the final cost of your order, so mentally tack on about $20 to the advertised prices to avoid sticker shock later on.

Note that the service fee fluctuates depending on the day of delivery. At Teleflora, for example, the standard fee for most the year is $14.99. But if you want the flowers delivered on Mother's Day, the fee is $21.99. If you want them delivered before 1 p.m., it's an extra $10.

If you don't think your mother would mind, check to see how much you could save by sending the flowers earlier. Teleflora's service fee is $16.99 for a Thursday delivery, $18.99 for a Friday delivery and $20.99 for a Saturday delivery.

Other selections you make also significantly increase the final price tag.

If it isn't included with the flowers, a vase may cost an extra $10. To upgrade to a larger bouquet, it might be another $20. All three sites also let shoppers add balloons, chocolates or stuffed animals to their orders. That could tack on as much as another $30 per item.

If the prices are too high even without the extras, try checking out some florists near your mom. It will take a little research to compare prices and options, but the Society of American Florists enables shoppers to search for local shops at www.nationalfloristdirectory.com.

Make 'em last

It's natural to have reservations about spending a lot on flowers because they only stay fresh for about a week. But careful selection and proper tending can ensure your mom gets the most bloom for your buck.

If you want flowers that will a bit last longer, keep the three C's in mind when browsing -- carnations, chrysanthemums and calla lilies.

That doesn't mean you should avoid more delicate flowers, such as freesia and irises. But if you're on the fence between a few options, consider which arrangements will have longer staying power.

If you want to learn more about the particular flowers in an arrangement, the Society of American Florists has a site that helps identify different varieties at http://tinyurl.com/6znvtlq.

The best way to make flowers last, however, is to make sure they're cared for properly. So before you call to wish your mom a happy Mother's Day, think of a cool spot in her home -- away from direct sunlight -- you can suggest for the arrangement.

If you don't want to seem overbearing with instructions, the main tip to get across is that the water should be changed daily to prevent bacteria from collecting.

If she's open to further suggestions, let her know that trimming the stems by about a half inch every other day will also clear any bacteria that may have collected at the bottom. And aside from the flower food that might come with a plant, it's better not to add any enhancers to the water.

Think outside the vase

If you don't want to send the standard mixed bouquet again this year, the three sites all offer plenty of flowering plants at comparable prices.

Orchids and tulips in particular are popular planted gifts. And although there's a perception that orchids are exotic and difficult to care for, Skaff notes that they actually require little attention. Other easy-care plants include miniature roses, calla lilies and hydrangeas.

If your mom has a green thumb, you might be interested in giving her a more finicky plant, such as gardenias and African violets. And as she tends to it throughout the year, she'll think of you.