Botanical name: Curcuma longa
Type: Herbaceous perennial, TROPICAL PLANT
Scarification/Stratification: Ideally, soak rhizome in room temperature kelp water for 12 hours before sowing warm, it helps speed things up.
Hardiness: The foliage is not frost tolerant but as long as a heavy mulch is laid, root will over-winter in temperate gardens of zone 7b or higher. Most growers dig up and over-winter rhizomes in a cool dark place, then replant in the spring. As one does this, one can snip off a good bit of root for consumption and/or multiplication of plant stock.
Sun requirements: Loves morning sun best, dabbled sun thereafter. After germination, the leaves will wilt in the hottest hours if in full sun, but springs back beautifully after shade hits it.
Water requirements: For germination, slightly damp soil. The rhizome has plenty of its own water. Once established, still moderate water.
Sow temp/season: If in zone 7b or higher, direct-sow in the container or garden bed it will grow in, in soils of 72-85F. This makes a bigger root system than transplanting. Some growers direct-sow plugs and lay down clear plastic to raise soil temperature.
Sow depth/spacing: Sow plugs two inches deep at 18 inch spacing, with the eyes pointing upward.
Germination time: 2-4 weeks depending on temperature and conditions. Sometimes longer, do not give up!! Temperature is key! In Southeastern NC where we are (zone 8b), sprouts are seen in June/July when temps are consistently in the 80s during the day.
Final spacing: 18 inches to 2 feet
Final height/spread: Five feet tall and two feet wide in one growing season.
Companion plants: Turmeric grows well with most plants. I would avoid growing turmeric near fennel though. I suggest planting one block of turmeric next to tomatoes, then turmeric, then cucumbers, etc. Avoid planting too close to root crops that would encroach on their allotted space.
Pest and disease resistance/susceptibility: Turmeric has many health and disease inhibiting compounds for humans and plants alike. As such, turmeric is resistant to most if not all soil-born diseases and pest insects except root rot and gophers, which is easily avoided by not drowning them and not having gophers! The soil turmeric is grown in becomes infused with its disease-fighting and pest-repelling compounds, which are many. We have been growing turmeric for several years in NC, and have not had any pests.