Flowers have been given as a sign of sympathy following death for thousands of years. The intention is to introduce a feeling of color and life back into a time when sadness is prevailing for friends and family of the deceased. While there are no hard and fast rules about how this is done, the following suggestions can help if you are not sure:
It is a traditional to send flowers to a funeral home or wake, but you can also send them directly to the family and/or primary person who is grieving. Some families ask that instead of flowers, you give a donation to a particular charity: it is still permissible to do both. You can also send flowers to a place of business associated with the diseased.
Families or groups of co-workers often go in together for a floral arrangement, but it is perfectly fine for you to also send one on your own. The vast majority of funeral homes will let the families have any flowers left behind and some will even deliver them. Some homes may have restrictions about the sort of plants that may be displayed (e.g. nothing in glass vases), however, so you might want to call ahead and check before placing an order.
Sending flowers to a funeral is appropriate for most any religion. However, if you are not sure, check with a friend of the family that is knowledgeable in this area. If flowers are not the best way to go, ask about what other gesture you can make instead.
If you wish for an arrangement to really reflect the deceased, choose flowers or an arrangement style that has some connection to them and their tastes. This can be something well known to everyone or just something that was special to your own relationship.