I would wait until the leaves turn 80% yellow and then clip them off at the soil line.

Keriann~

Thank you Keriann. Does this process encourage the bulbs to multiple or just feed the ones that are there? I dont want any more tulips to come up than I have planted.

What I do is wait until the connection between the foliage and bulb naturally weakens, then gently tug the whole stem and leaves out of the ground. I prefer this to clipping because clipping leaves several inches of the old stem in the ground to decompose.

Roseabby, if you don't want your tulip bulbs to split, the thing to do is don't water them. But, pretty much all bulbs will naturally split. Small newly-split tulip bulbs do not produce flowers, just foliage. The only way to have the exact same number bloom every year is to dig them up and plant new ones in their place each fall.

Thank you sunandshadow. I cant avoid not watering the bulbs as we have a sprinker system that waters the beds. I just didnt want the tulips to overtake my beds, so I am hoping they dont multiply too much!

With any bed of bulbs (e.g. tulips, lilies, daffodils, hyacinths, etc.) or rhizomes (e.g. irises) you should expect to dig it up every 3-4 years. Many varieties of tulips are poor perennializers though - it's common to see tulips which bloom for about two years, then the bed only produces foliage because all the bulbs have split, and the new small bulbs won't flower until they get bigger. Many people treat tulip bulbs as an annual, discarding the ones in the ground and replacing them with new-bought bulbs every year, or every 2 years. If you specifically want to plant tulips once and have them survive and keep flowering for years you have to do a bit of research and use one of the varieties which is good at that.