Vegetable
Spinach
Spinacia oleracea · Amaranthaceae
Also called: True spinach, Garden spinach
Spinach (Spinacia oleracea) is a moderate-water vegetable well suited to Tucson and the low desert. It's a fast-growing vegetable.
Spinach at a glance
- Water use
- Moderate (established)
- Sun
- Full sun in the cool season; tolerates partial shade. Long, warm days trigger bolting, so it is a short-day cool-season crop here.
- Mature size
- 6-12 in tall, forming a low rosette 6-10 in wide.
- Growth rate
- Fast
- Bloom
- Inconspicuous greenish/yellowish (bolting flower stalk; not desirable), Bolts in spring as days lengthen and temperatures rise - harvest before bolting.
- Cold hardiness
- Cold-hardy cool-season annual; tolerates frost and light freezes well (one of the more freeze-tolerant greens). Bolts quickly once days lengthen and temps rise in spring - not a summer crop in the low desert.
- Soil
- Rich, well-drained soil with plenty of organic matter; prefers near-neutral pH 6.5-7.0 (sensitive to acidic soil).
- Native range
- Central / Southwestern Asia (Persia)
- Best used as
- Cool-season leafy green (salads, cooking), Fall/winter raised-bed and container crop, Cut-and-come-again harvesting, Cold-frame/winter gardening
- Wildlife
- Minimal wildlife value.
- Toxicity
- Non-toxic, edible. High in oxalates (moderate intake advised for those prone to kidney stones). Safe for people; not toxic to pets.
How to grow Spinach in Tucson & the low desert
Watering
Cool-season crop: direct-sow from late September through January/early February in Tucson (fall and winter are ideal). Keep soil consistently and evenly moist - spinach is shallow-rooted and bolts or yellows under drought or heat stress. Water frequently and moderately; mulch to keep roots cool and moisture steady.
Fertilizer & nutrients
Nitrogen-loving leafy crop. Amend with compost and side-dress with a nitrogen-rich fertilizer (or fish emulsion/blood meal) every 2-3 weeks for dark, full leaves. Steady nitrogen is key to good production.
Pruning & care
No pruning. Harvest outer leaves as cut-and-come-again, or pull whole plants before warm weather and lengthening days cause bolting.
Notes
Strictly a cool-season crop in Tucson (Oct-Feb); it cannot take the heat - for a summer 'spinach,' grow Malabar spinach instead. Sow in fall for the best, longest harvest before spring bolting.
Sources: University of Arizona Cooperative Extension / Pima County Master Gardeners cool-season vegetable calendar; Tucson Organic Gardeners Planting Guide; Growing in the Garden (Arizona low desert)