Measure the planting container to determine the soil’s depth. If the pot is filled to within one-half or 1 inch of the rim, deduct that amount from the total depth.
Stick the chopstick into the soil to the bottom of the planting container halfway between the plant's main stem and the side of the pot. Allow it to sit in the soil for five minutes.
Pull the chopstick out and look at it. If soil sticks to it or if it is wet, measure the distance from the bottom of the chopstick to the top of the wet or soiled portion with a tape measure. Deduct this measurement from the pot's depth measurement to learn how many inches of the soil are dry.
Water the plant immediately if the chopstick is completely dry when you pull it from the soil, unless the plant's care requirements specify otherwise.