Cardamom is a tropical plant native to the southern parts of India in an area called the Cardamom Hills. It is in the ginger family and produces aromatic pods filled with reddish-brown seeds that are a primary ingredient in curry. Cardamom will only flower and fruit in tropical locations, so growing the plant in the United States will require a heated greenhouse, or it can be grown in subtropical locations as a foliage plant. The plant rises from rhizomes and produces pointed lance-shaped leaves in a low mounding habit. The flowers are attractive clusters 2 feet long in white or yellow with lilac or pink interior markings.
Plant the rhizome in a pot filled with 2 parts each of potting soil and peat and 1 part of manure. The peat will provide a high acid level which cardamom needs, and the manure will begin to gently provide nutrients when the plant sprouts. Plant the rhizome 2 to 3 inches deep and brush the soil mixture over it and press down.
Water the pot until the water runs out of the drainage holes and it is evenly moist. Place it in the greenhouse or in a warm bathroom that gets a lot of shower use. The temperature needs to be a minimum of 21.7 degrees Celsius and humidity very high.
Place the pot on a saucer that has a layer of pebbles at the bottom. Fill it with 1 inch of water. The evaporation of the water will moisten the air around the plant. You should also mist the plant daily to moisten the leaves. Water the pot at least once a week and never let it dry entirely out. Stick a finger in to the second knuckle to ensure that the soil is damp.
Provide shade once the rhizome sprouts. You may have to move it to a sheltered part of the greenhouse or tack up a sheet over the window to give indirect light. Make sure you choose a permanent location for the plant as it doesn't like to be moved.
Fertilise the cardamom plant three times during the growing season. In mid-spring apply a household plant food diluted in the irrigation water. Dissolve 1 tsp of granular food per gallon of water. Divide the fertiliser application evenly over the growing season with the last one in early August.