What a plant needs

A plant makes its own food. In its leaves, green chlorophyll captures light and uses that energy to turn water and carbon dioxide from the air into sugars, releasing oxygen as a by-product. This process is photosynthesis, and almost everything you do as a grower is about keeping it running.

That gives you a short list of needs. Light powers the process. Water comes up through the roots. Air reaches the leaves through tiny pores called stomata, which the plant closes when it is hot and dry to save water. Roots need a potting mix that holds some moisture but drains, in a pot with drainage holes. The plant also needs mineral nutrients such as nitrogen, phosphorus and potassium, which in a pot only arrive if you fertilise. Temperature matters too: most houseplants are comfortable at roughly 18–24 °C by day, a little cooler at night.

Care guides group these basics as light, water, growing medium, temperature and humidity, and every species wants a slightly different amount of each. The rest of this course takes them one at a time. For now, remember that a plant rarely fails for a mysterious reason; usually one of these basics is out of balance.