Planting Time and USDA Hardiness Zone
As a first-time blackberry grower, the first decisions facing you are which cultivars to plant and when to plant them. Different cultivars grow in different parts of USDA hardiness zones 4 through 9, so your choices will be limited by your location in those zones.
Deciding when to plant your blackberries, however, is a bit easier. The simple answer is purchase dormant, bare-root bushes and plant them in late fall or as soon as you can work the soil in early spring. In places where hard freezes are rare, this could be up to six weeks before the average last spring frost date.
Expert gardener’s tip: The damp, cool conditions common in fall and early spring allow your newly planted blackberries time to adjust in their location before the heat of summer sets in.
Planting in USDA Hardiness Zone 9
If you live in USDA zone 9 and enjoy a Mediterranean climate where spring, summer and fall are warm and mostly dry, plant your blackberry bushes at the start of the winter rains.
Heat-tolerant cultivars for zones 8 (for fall and spring planting) or 9 include:
- Trailing, thornless ‘Doyle’s’, USDA zones 4-8. An extended fruiter, it needs insulating with a layer of organic mulch where zone 8 temperatures drop below 13°F (-10.6°C).
- Erect, thornless ‘Chester,’ USDA zones 5-8.
- Erect, thornless ‘Triple Crown,’ USDA zones 6-9.
- Erect, thornless ‘Hull’, USDA zones 6-9.
For a blackberry crop that starts ripening in June and continues well into September, plant all four varieties.
Heeling In
What if you simply run out of time to plant your bushes before summer heat sets in? Then heeling them in can buy you a bit of time:
- Clean the roots of packing material and soak them in water for between four and seven hours.
- Dig a sloping trench with one side higher than the other. Put it where there will be afternoon shade as the temperatures rise.
- Angle your bushes in the trench with their canes just above the lip of the steep side.
- Refill the trench with soil, tamping gently to eliminate air pockets around the roots. Water well.
Wait no more than a month to transplant the bushes to their permanent home.
