Shrub
Thornless Blackberry 'Arapaho'
Rubus subgenus Rubus 'Arapaho' (commonly sold as Rubus fruticosus 'Arapaho'; a University of Arkansas erect blackberry hybrid) · Rosaceae
Also called: Arapaho erect thornless blackberry, Bramble
Thornless Blackberry 'Arapaho' (Rubus subgenus Rubus 'Arapaho' (commonly sold as Rubus fruticosus 'Arapaho'; a University of Arkansas erect blackberry hybrid)) is a moderate-water shrub well suited to Tucson and the low desert. It's a fast-growing shrub.
Thornless Blackberry 'Arapaho' at a glance
- Water use
- Moderate (established)
- Sun
- Full sun for best fruiting, but in Tucson provide afternoon/filtered shade to reduce heat and sun stress on canes and berries; morning sun with light afternoon shade is ideal in the low desert.
- Mature size
- Erect, self-supporting canes 4-6 ft tall, 3-4 ft wide; does NOT need a trellis (unlike trailing blackberries).
- Growth rate
- Fast
- Bloom
- White (to pale pink) flowers; fruit ripens green to red to glossy black., Blooms spring; ripens early-to-mid summer (roughly late May-June in the low desert, ahead of peak heat).
- Cold hardiness
- Cold-hardy (USDA zones 4-9); fully winter-hardy in Tucson. The challenge here is heat, not cold — canes and fruit can scorch in extreme summer sun and heat.
- Soil
- Rich, well-drained soil amended with organic matter; mulch heavily. Prefers slightly acidic to neutral pH (5.5-7.0), so amend Tucson's alkaline soil with compost and use acidifying mulch; iron chlorosis can appear in high-pH soil.
- Native range
- Cultivated hybrid from the University of Arkansas breeding program (released 1993); blackberries are native to North America/Eurasia but this cultivar is a bred selection.
- Best used as
- Edible berries (fresh, jam, baking), Edible hedge/border, Wildlife/pollinator support
- Wildlife
- Flowers attract bees and pollinators; fruit eaten by birds. Thornless canes are easier to harvest and manage than wild brambles.
- Toxicity
- Non-toxic; berries edible and safe for people and pets.
How to grow Thornless Blackberry 'Arapaho' in Tucson & the low desert
Watering
Needs consistent moisture, especially during flowering and fruiting (late spring); drip irrigation 2-3 times per week in peak summer heat. Mulch 3-4 in deep to conserve moisture and cool roots. Reduce water after harvest and in winter dormancy.
Fertilizer & nutrients
Feed in early spring as growth begins with a balanced fertilizer (or one for acid-loving/berry plants), and apply chelated iron and soil sulfur to counter alkaline-soil chlorosis. Side-dress with compost. Avoid heavy nitrogen late in season.
Pruning & care
Floricane-fruiting (biennial canes): primocanes grow year one, fruit year two then die. Tip primocanes at ~3.5-4 ft in summer to force laterals; after harvest remove the spent floricanes at ground level. Thin to ~4-6 strong canes per plant.
Notes
Low-chill (~400-500 hrs) and self-fertile, making 'Arapaho' one of the better blackberries for the low desert. Classified here as a Shrub because it is an erect, self-supporting cane (not a true climbing vine) — it does not climb or need a trellis. Key Tucson management: afternoon shade, heavy mulch, consistent water in fruiting season, and correcting iron chlorosis from alkaline soil. Best harvest is before the hottest weeks of summer.
Sources: University of Arkansas (cultivar release info); University of Arizona Cooperative Extension (small fruit for the home garden); Oklahoma State / regional extension blackberry culture guides