Since coffee grows naturally in the understory of tropical forests, raising coffee trees indoors is possible. Comfortably warm temperatures and a large pot situated near a sunny south window may be enough to sustain this very slow growing tree. Outdoors, the tree may not bear coffee cherries for three to five years. Indoor plants should be even slower to produce and will require special attention.
Indoor Coffee Trees
Decide between a nursery planted tree or growing a tree from seed. If nursery stock is chosen, inspect the plants before purchase or immediately after receiving shipment. Refuse any with bark damage. Coffee plants root deeply--large plants in small pots will be root-bound. Buy smaller plants in larger containers and transplant to roomier pots as necessary.
Soak green coffee beans overnight in warm water if planting from seed. Unroasted new crop beans will be viable if after soaking the seeds show a white swelling bump on one end. Actual germination could take from two to six months. After soaking for 24 hours plant several seeds in small flower pots, 1 1/2 inches deep. Keep the potting soil damp and warm until the sprout emerges. Coffee germination rates are very low--as few as two in every 100 seeds survive.
Fertilize the coffee plant after two months and every two months thereafter with an NPK fertilizer which also includes magnesium. Iron sulphate should be applied three or four times during the summer--use the iron as a dry powder in acid or neutral soil and as a wet wash in alkaline soil. Water frequently but only enough to keep the soil damp.
Prune the coffee plant lightly. Cut vertical branches back to the main limb or the trunk. Be careful not to injure the tree's bark and don't cut into the branch collar--a swelling ring of tissue around the base of the branch. Encourage bushing out horizontally by clipping the central leader when the plant reaches 2 1/2 feet in height. Cut the plant back to about 20 inches tall.
Stimulate fruiting in plants at least four years old by holding back water in January and February and resuming regular watering in March and April. Branches grow for two years before producing coffee cherries, and die back after three to five years. Allowing vertical growth replaces the lost lower limbs and continues production. When lower limbs have died off, cut the coffee plant back to 20 inches high and begin the cycle again.