Question
I have potted gerberas which give a single bloom at a time and that too long after the earlier bloom has died. Also the blooms are becoming smaller in size. Will fertilizing with a solution of urea help?

Answer
The plants we buy in the nurseries are grown under amazing care, and conditions. So we are faced with trying to reproduce those conditions, to get the same amazing results.
Gerberas are not easy plants to grow. But understanding them may be a big help for you to grow them.
They are first of all, very sensitive to heat, light, and moisture. So, this means neither too much, or too little of any of these things. It would be helpful to know where you are growing them. But, as a general rule, if you have a hot location, use morning sun, afternoon shade. In cool areas, full sun. Remember, the more light, the more flowers. Let the soil dry to near wilt, then water thoroughly. DO NOT GET WATER ON THE PLANT just on the soil around the plant. These plants are a magnet for fungus, and crown rot. Keep the old flowers and leaves pick off. The plant will be healthier, and look better, and flower more.
Fertilize every two, to three weeks with a low nitrogen fertilizer. Urea is high in nitrogen. It will make the leaves grow, but not produce flowers. African violet fertilizer is recommended. But any fertilizer that promotes blooming will work. When the temperature goes above 90 degrees, you will see less flowering, and growth. This is normal. Plants tend to go "heat dormant". When this happens, stop fertilizing. The plant will only be more stressed if you feed it. When it cools again, and the plant begins to show growth again, then resume the fertilizer.
The advantage of growing in a container, is you have more control over the conditions. But, it make take some experimenting to find the best ones.