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Prime-Ark 45 Blackberry

Rubus subgenus Rubus 'Prime-Ark 45'

The first truly successful primocane-fruiting blackberry that produces large, firm berries on both first and second-year canes for extended harvests. This thornless variety delivers exceptional fruit quality with sweet, flavorful berries that rival the best traditional blackberries. The compact, manageable growth habit makes it perfect for home gardens where space is at a premium.

Harvest

60-70d

Days to harvest

📅

Sun

Full sun

☀️

Zones

6–9

USDA hardiness

🗺️

Difficulty

Moderate

🌱

Planting Timeline

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Transplant

Harvest

Transplant

Harvest

Showing dates for Prime-Ark 45 Blackberry in USDA Zone 7

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Zone Map

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Prime-Ark 45 Blackberry · Zones 6–9

What grows well in Zone 7? →

Growing Details

Difficulty

Moderate

Spacing3-4 feet apart

SoilWell-drained, fertile soil with organic amendments

pH5.5-7.0

Water1-2 inches per week, consistent moisture

SeasonPerennial, fruiting summer and fall

FlavorSweet with mild tartness, rich blackberry flavor

ColorDeep black with glossy finish

SizeLarge, 1-1.5 inches long

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
Zone 6	—	May – July	—	July – October
Zone 7	—	May – June	—	July – October
Zone 8	—	April – June	—	June – November
Zone 9	—	March – May	—	May – December

Complete Growing Guide

Soil: Clay, High Organic Matter, Loam (Silt), Sand. Soil pH: Acid (<6.0). Drainage: Good Drainage, Moist, Occasionally Dry. Growth rate: Rapid. Maintenance: Medium. Regions: Coastal, Mountains, Piedmont.

Harvesting

Fruits vary in size and color with many maturing to black or red. Usually edible but vary in taste and sugar content. They also vary as to when they are available.

Type: Aggregate, Drupe.

Garden value: Edible

Bloom time: Spring, Summer

Storage & Preservation

Fresh Prime-Ark 45 blackberries keep best when stored unwashed in shallow containers in the refrigerator at 32-35°F with high humidity. They maintain quality for 5-7 days when properly stored, longer than most primocane varieties due to their exceptional firmness. Line containers with paper towels to absorb excess moisture and prevent mold.

For freezing, rinse berries gently and pat dry, then freeze on baking sheets before transferring to freezer bags — this prevents clumping. Prime-Ark 45's firm texture makes it excellent for cobblers and pies even after freezing. The berries also make superior jam due to their balanced sweet-tart flavor and natural pectin content. Dehydrate at 135°F for 8-12 hours for chewy dried berries that retain more flavor than most varieties due to their concentrated sweetness.

History & Origin

Prime-Ark 45 was developed by Dr. John Clark at the University of Arkansas and released in 2009 as part of their groundbreaking primocane-fruiting blackberry breeding program. This variety represents a major breakthrough in blackberry genetics — it was the first commercially viable primocane-fruiting blackberry that could reliably produce two crops per year while maintaining fruit quality comparable to traditional floricane varieties.

The University of Arkansas has been the world leader in blackberry breeding since the 1960s, developing over 40 varieties including most thornless types. Prime-Ark 45 was selected from thousands of seedlings for its combination of primocane-fruiting ability, thornless canes, large berry size, and excellent flavor. The 'Prime-Ark' name reflects Arkansas's leadership in primocane breeding, while '45' refers to its selection number in the breeding program.

This variety solved a major challenge that had frustrated breeders for decades — previous primocane blackberries produced small, seedy berries with poor flavor. Prime-Ark 45 changed the industry by proving that primocane varieties could match traditional blackberries in all quality measures while extending the harvest season.

Advantages

+Disease resistance: Drought
+Attracts: Pollinators, Small Mammals, Songbirds
+Wildlife value: Fruits attract birds. Provides nectar for bees, food for birds and mammals, and thickets provide shelter for small mammals. Dead stems are used by stem-nesting bees.
+Fast-growing

Companion Plants

Plant Together

Chives

Repels aphids and Japanese beetles while improving soil with sulfur compounds

Marigold

Deters nematodes and aphids through natural pest-repelling compounds

Garlic

Repels aphids, spider mites, and fungal diseases with strong aromatic oils

Comfrey

Deep roots bring nutrients to surface, leaves make excellent mulch and fertilizer

Nasturtium

Acts as trap crop for aphids and cucumber beetles, attracts beneficial insects

Clover

Fixes nitrogen in soil and provides ground cover to suppress weeds

Yarrow

Attracts beneficial insects and improves soil health with deep taproot

Tansy

Repels ants, mice, and flying insects while attracting beneficial predators

Keep Apart

Black Walnut

Produces juglone toxin that inhibits growth and can kill blackberry plants

Raspberries

Share common diseases like anthracnose and verticillium wilt, increasing infection risk

Pine Trees

Acidify soil excessively and compete for nutrients, creating poor growing conditions

Nutrition Facts

Calories

43kcal(2%)

Protein

1.39g(3%)

Fiber

5.3g(19%)

Carbs

9.61g(3%)

Fat

0.49g(1%)

Vitamin C

21mg(23%)

Vitamin A

11mcg(1%)

Vitamin K

19.8mcg(17%)

Iron

0.62mg(3%)

Calcium

29mg(2%)

Potassium

162mg(3%)

Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #173946)

Pests & Disease Resistance

Resistance

Good resistance to orange rust and anthracnose

Common Pests

Spotted wing drosophila, aphids, thrips, birds

Diseases

Cane blight, crown gall, rosette disease

Frequently Asked Questions

How long does Prime-Ark 45 blackberry take to produce fruit?▼

Prime-Ark 45 produces its first harvest on primocanes (first-year canes) within 4-6 months of planting, typically in late summer or fall. The second harvest occurs the following early summer on the same canes (now floricanes). This unique characteristic allows you to get fruit much faster than traditional blackberries that require two full years to produce.

Can you grow Prime-Ark 45 blackberries in containers?▼

Yes, Prime-Ark 45 grows well in large containers due to its compact growth habit. Use containers at least 20-24 inches wide and deep with excellent drainage. You'll need to provide a trellis system and may sacrifice some yield compared to ground-planted berries. Container plants require more frequent watering and fertilizing, and protection from extreme cold in northern zones.

Is Prime-Ark 45 good for beginner gardeners?▼

Prime-Ark 45 is moderately challenging for beginners due to its unique pruning requirements and need for proper cane management. However, its thornless nature, disease resistance, and forgiving growth habit make it easier than many blackberry varieties. New gardeners who understand the dual-cropping system and invest in proper trellising will find success with this variety.

What does Prime-Ark 45 blackberry taste like?▼

Prime-Ark 45 berries have a classic sweet blackberry flavor with mild tartness and rich, complex notes. The flavor is well-balanced and pleasant for fresh eating, though not as intensely flavored as some premium floricane varieties. The berries are notably firm and juicy with small, soft seeds that are less noticeable than in many blackberry varieties.

When should I plant Prime-Ark 45 blackberry plants?▼

Plant Prime-Ark 45 in spring after the last frost date when soil temperatures reach 60°F consistently. In most regions, this means April through May. Spring planting allows the plants to establish strong root systems and produce their first primocane fruit crop in late summer. Avoid fall planting in zones 6 and colder, as plants need time to establish before winter.

How do you prune Prime-Ark 45 blackberries for maximum harvest?▼

For dual-cropping, remove spent floricanes after early summer harvest, leaving primocanes to fruit in fall. In late winter, tip-prune these canes to 5-6 feet to encourage branching. For single-crop management, cut all canes to 2 inches in late winter for one large fall harvest. This simpler approach often produces higher yields and better fruit quality in northern zones.