How you fertilize and what type of fertilizer you use is dependent on what kinds of plants or crop you grow in your greenhouse, because every crop has a particular requirement with regards to nutrients, and this requirement should be met.
For house plants, it is usually much easier to fertilize a large group together. Generally, plants need to be fertilized every one or two months while there is rapid growth and all throughout the winter season, twice or once only.
Alternatively, you can apply the fertilizer more frequently when using a liquid fertilizer diluted in water; this familiarizes certain plants that otherwise be injured when you use a fertilizer of full. Generally half of the recommended strength or dosage means that you use only half fertilizer in every plant.