Herb
Sweet Basil
Ocimum basilicum · Lamiaceae
Also called: Genovese basil, Common basil, Sweet Genovese
Sweet Basil (Ocimum basilicum) is a moderate-water herb well suited to Tucson and the low desert. It thrives in full sun in cooler months, with a fast growth rate. Expect white to pale lavender blooms summer.
Sweet Basil at a glance
- Water use
- Moderate (established)
- Sun
- Full sun in cooler months; in the peak of Tucson summer it benefits from light afternoon shade to prevent wilting and leaf scorch.
- Mature size
- 12-24 in tall and about 12-18 in wide (cultivar dependent).
- Growth rate
- Fast
- Bloom
- White to pale lavender, Summer (bolts readily in heat; flowering is generally removed to prolong leaf harvest).
- Cold hardiness
- Frost-sensitive; damaged at ~40 F and killed by frost. A summer annual in Tucson; struggles below 50 F and in extreme 105 F+ heat without afternoon shade.
- Soil
- Rich, well-drained soil amended with compost; pH 6.0-7.0.
- Native range
- Tropical Asia and Africa (central Africa to Southeast Asia)
- Best used as
- Culinary herb (pesto, sauces, salads, garnishes), Container/kitchen-garden herb, Pollinator plant if allowed to flower, Companion planting with tomatoes/peppers
- Wildlife
- Flowers attract bees and other pollinators.
- Toxicity
- Non-toxic and culinary; considered safe (essential oils can cause mild GI upset in pets only in large quantities).
How to grow Sweet Basil in Tucson & the low desert
Watering
Warm-season herb: plant transplants or sow seed after frost danger passes, about mid-March through summer; it is killed by frost so it is an annual here. Keep soil evenly moist - basil wilts quickly in dry desert heat. Water deeply and often (daily or every other day in summer beds, more in containers). Mulch helps hold moisture.
Fertilizer & nutrients
Light feeder. Amend with compost at planting and side-dress with a balanced or slightly nitrogen-forward fertilizer (or fish emulsion) every 3-4 weeks during active growth for lush leaves. Avoid over-fertilizing, which dilutes flavor.
Pruning & care
Pinch/harvest from the top regularly above a leaf node to keep plants bushy and productive. Remove flower spikes promptly - once basil bolts and flowers in the heat, leaf flavor declines.
Notes
A reliable warm-season herb for Tucson. Provide afternoon shade and steady water during June-August to reduce bolting and scorch. Replant or take cuttings to extend the season; it will not survive winter outdoors.
Sources: University of Arizona Cooperative Extension / Pima County Master Gardeners herb guidance; Green Things Nursery (Tucson) vegetable & herb planting guide; Growing in the Garden (Arizona low desert)