They still need a constant supply of nutrients, even though the metabolism of plants growing in the shade is slower than that of those growing in the sun. Monthly application of a relatively moderate fertilizer that is whole is an excellent practice when the plants are actively growing. A light fertilizer might be a liquid fish emulsion with a 5-1-1 formula, or a dry 5-10-5 fertilizer. (The numbers refer to the percentages of nitrogen, phosphorus, and potassium found in the fertilizer, and are consistently recorded in that order.
Acid loving plants can be given. These fertilizers are often labeled “azalea and camellia food,” “rhodod endron and azalea food,” or something similar.
The speeds and times of any fertilizer have been the subject of much research and should not be taken Too much for use can rapidly damage plants.