New leaves smaller than the old

[orchidsamore]

A combination of everything that causes plants to grow.

You are probably not watering as consistent as a nursery greenhouse (consistency not quantity) and the same with fertilizer. Many nurseries fertilize several times a week, much more than hobbyist. Again consistency is important. Temperature and humidity affect watering and the ability of the plant to retain moisture and its growth size.

An example is that in Florida heat, it is impossible without extensive cooling to grow Oncidium as large as they are grown on Hawaiian mountain sides. The plants stay smaller to retain moisture evaporation.

Similarly Hawaii does not get the growth rate on Cattleya that we get in our Florida heat.