Vegetable amaranth is a leafy green that keeps producing through Florida's summer heat, when most greens give up; many Floridians know it as callaloo. Its leaves come in green, red or variegated forms. Cold kills it, so it is a warm-season crop, and in wet weather the main worry is a fungal wet rot of the stems.1, 2
When to plant amaranth (vegetable amaranth, callaloo) in Florida
Region
Months on the UF/IFAS calendar
North Florida
Apriltransplant with care · Maytransplant with care · Junetransplant with care · Julytransplant with care
Central Florida
Marchtransplant with care · Apriltransplant with care · Maytransplant with care · Junetransplant with care · Julytransplant with care
South Florida
Januarytransplant with care · Februarytransplant with care · Marchtransplant with care · Apriltransplant with care · Maytransplant with care · Junetransplant with care · Julytransplant with care · Augusttransplant with care · Septembertransplant with care · Octobertransplant with care · Novembertransplant with care · Decembertransplant with care
3 (Gardening Solutions, after thinning); 6 (EDIS HS1407, after thinning seeds sown 1 inch apart)
Between rows (inches)
12 to 18
Days to harvest
3 to 6 weeks after planting for young leaves and shoot tips (Gardening Solutions); about 30 days after seeding (HS1407)
Seed germinates in about a week; 70°F to 75°F is the best range, germination is quick above 68°F soil temperature and may fail below 50°F. HS1407 gives the earliest planting as May in north Florida (Zone 8), April in central Florida (Zone 9) and December to February in south Florida (Zones 10 and 11). Thinned seedlings can be eaten as microgreens. Transplant only while plants are young; late transplanting can trigger early flowering.
Moderately drought tolerant, but a serious water shortage brings on early flowering and lowers yield. Keep the soil evenly, moderately moist; water standing around the roots can rot them. Drip or micro-sprinklers suit small plantings.
Fertilizer
HS1407 says there is no Florida fertilizer recommendation for amaranth and that fertilizer has not raised yields much; too much nitrogen can make leaves pale and build up nitrate in the plant.
Grows best between 70°F and 85°F and tolerates 50°F to 110°F, but dies below 40°F from chilling injury. Plants can reach 5 feet tall and 2 feet wide and may need staking.
Pull whole plants for a single harvest, or cut part of the leaves and let the plant regrow for another cutting about two weeks later. Once flowering starts there are fewer leaves worth picking. Leaves wilt quickly after harvest; HS1407 recommends a short cooling at 40°F to 55°F, and notes that leaves held at room temperature (77°F) can lose 88% of their vitamin C.
In an aquaponics system
We haven't found a published source that covers amaranth (vegetable amaranth, callaloo) in aquaponics systems, so this lesson doesn't guess. The planting months above apply to a grow bed the same as to soil; the water does the watering.
What this lesson doesn't cover yet
Amaranth is not in the planting table of the Florida Vegetable Gardening Guide (SP 103), so there are no SP 103 figures for it.
No UF/IFAS list of varieties tested in Florida was found. 'Tampala' is cited in HS1407 as suited to the southern United States, not as a Florida trial result; Gardening Solutions shows a cultivar called 'Tiger Stripe' only in a photo caption.
Neither SRAC 454 nor the FAO aquaponics manual mentions amaranth, so suitability for aquaponics is not documented.
HS1407's pest paragraph attributes 'white rust' to damping-off fungi (Pythium, Rhizoctonia), which reads as an error in the source; white rust was left out of this lesson.
Your county extension office and its Florida Master Gardeners can fill these in for your garden.