I was just going through on what each colour Rose means. I got the following details about it, but found that almost all flowers has meanings and can be used for the appropriate function or moment or occasion.

Rose:


Long a symbol of love and passion, the ancient Greeks and Romans associated roses with Aphrodite and Venus, goddesses of love. Used for hundreds of years to convey messages without words, they also represent confidentiality. In fact, the Latin expression "sub rosa"(literally, "under the rose") means something told in secret, and in ancient Rome, a wild rose was placed on the door to a room where confidential matters were being discussed. The number of stems in a rose bouquet can also express specific sentiments.

Each color offers a distinct meaning:
red, the lover’s rose, signifies enduring passion;
white, humility and innocence;
yellow, expressing friendship and joy;
pink, gratitude, appreciation and admiration;
orange, enthusiasm and desire;
white lilac and purple roses represent enchantment and love at first sight.

The complete flowers meaning list is.....

Alstroemeria - aspiring
Amaryllis - dramatic
Anemone - fragile
Apple Blossom - promis
Aster - contentment
Azalea - abundance
Baby's Breath - festivity
Bachelor Button - anticipation
Begonia - deep thoughts
Black-Eyed Susan - encouragement
Camellia - graciousness
Carnation :
pink - gratitude
red - flashy
striped - refusal
white - remembrance
yellow - cheerful
Chrysanthemum :
bronze - excitement
white - truth
red - sharing
yellow - secret admirer
Cosmos - peaceful
Crocus - foresight
Daffodil - chivalry
Delphinium - boldness
Daisy - innocence
Freesia - spirited
Forget-Me-Not - remember me forever
Gardenia - joy
Geranium - comfort
Ginger - proud
Gladiolus - strength of character
Heather - solitude
Hibiscus - delicate beauty
Holly - domestic happiness
Hyacinth - sincerity
Hydrangea - perseverance
Iris - inspiration
Ivy - fidelity
Jasmine - grace and elegance
Larkspur - beautiful spirit
Lavender - distrust
Lilac - first love
Lily :
Calla - regal
Casablanca - celebration
Day - enthusiasm
Stargazer - ambition
Lisianthus - calming
Magnolia - dignity
Marigold - desire for riches
Nasturtium - patriotism
Orange Blossom - fertility
Orchid - delicate beauty
Pansy - loving thoughts
Passion flower - passion
Peony - healing
Poppy - consolation
Queen Anne's Lace - delicate femininity
Ranunculus - radiant
Rhododendron - beware
Rose :
pink - friendship
red - passionate love
red & white - unity
white - purity
yellow - zealous
Snapdragon - presumptuous
Star of Bethlehem - hope
Stephanotis - good luck
Statice - success
Sunflower - adoration
Sweetpea - shyness
Tuberose - pleasure
Tulip :
pink - caring
purple - royalty
red - declaration of love
white - forgiveness
yellow - hopelessly in love
Violet - faithfulness
Wisteria - steadfast
Yarrow - good health
Zinnia - thoughts of friends