This is a common problem. The cuttings like to be kept between 72 and 80 deg. F., if the temperature increases or decreases the cutting will root slower. As much as I hate to admit it, there are a few disadvantages to growing with hydroponics. The most obvious disadvantage of hydroponic gardening is the initial cost.
Some hydroponic systems are very expensive.
Which means that in the long run it may actually be cheaper to garden hydroponically. There are many ways to grow hydroponically that are practically free, and building a system yourself can bring the price down to less than that of a good shovel, rake and hoe. Some hobby hydroponic systems are very susceptible to power outages. Hobby gardeners might have to hand water their systems in the event of a long term power outage. There are many people that think organically grown produce tastes and smells better than hydroponically grown.