Fertilization is the catalyst for growth, and light is the energy driver of growth. Both are needed for effective plant growth. If plants get leggy and pale, they may need more light. Plants that are not growing may need a combination of more fertilizer and light. It is recommended that you fertilize only during the growing season, although rare exceptions can be made for winter fertilization.
From spring to fall is the growing season. The most vigorous growth of plants will be in the summer when the sun is up and out the longest. During winter, the sun is neither as high in the sky, nor in the sky for as long as it is in the summer. For your plants, that means less light. For some plants, this may trigger dormancy. This is not to be confused with deciduousness though. Dormancy simply means a stunt in growth. Deciduous plants lose their leaves in preparation for winter. Most houseplants are non-deciduous, however, due to the lack of light, your plants may drop a few leaves. This results from lack of light rather than deciduousness. If your plant drops a few leaves in winter it is just adjusting to the fluctuating light levels.
Type: Any plant that you can plant from a seed and flowers to make seeds in a few months is a fast grower. Herbs, veggies, outdoor plants, garden flowering plants, begonias, oxalis, geraniums, pileas are all fast growers. Usually, these plants are from temperate environments where the race to reproduce is on. Temperate plants must go from seed to seed in a few months time, and if they don’t, winter frost will end their chances.
Growth Rate: You will notice a difference in plant size week after week.
Fertilization: Once every 2 weeks.
Type: Most houseplants are medium growers. Pothos, Calatheas and many succulents (but not cacti), monsteras, most aroids, peperomias, and some orchids. Given more light, they will grow faster. Most of these will do optimally with a few hours of sun, and bright, indirect light the rest of the time.
Growth Rate: You will see growth differences from month to month.
Fertilization: Once a month.
Type: Any plant in low light. Cacti, some succulents, ponytail palms, dracaenas, some orchids, bird of paradise plants, marimos. Irrespective of light, cacti tend to grow slowly because they are built to.
Growth Rate: Any plant in low light will not have energy to grow at all, and may either go into dormancy, or try to grow spindly or pale in an effort to find light.
Fertilization: Once every 3 months.