Blackberries are one of summer’s finest treats. The flavor of a sun-ripened blackberry is exquisite and unique. As a kid, more made it into my mouth than the little pail hanging from a string around my neck. If your memories of blackberries are of carefully reaching through thorny brambles to pick a few berries, you might be in for a surprise. Modern cultivated blackberries are larger, less thorny (most are thornless), and provide impressive yields. They’re easy to grow and easier to harvest.

Blackberries are perennial bushes or brambles with biennial canes (the arching stems), meaning the canes live for two years. Their first year, after popping up from the crown, they’re called primocanes. Two-year-old canes are called floricanes. Blackberries produce new canes yearly from buds on their crowns.

Primocanes are more supple and less woody. They grow rapidly in spring and summer, and set next year’s flower buds in late summer and fall. After overwintering, these second-year canes become floricanes. 

On wild blackberries and most blackberry cultivars, it is the second-year canes, or floricanes, that flower and bear fruit. Berries are borne on shoots from lateral buds on the floricanes. After fruiting, the floricanes dry up and die. In a wild, unmanaged bramble patch, you can see these brown and gray, brittle, dead (and thorny) floricanes side by side with live canes. 

Every year, new primocanes pop up from the crown, forming a cycle in which there is always a generation of primocanes and a generation of floricanes, producing fruit each year. However, a few new cultivars have been developed that bear fruit on primocanes or on both primocanes and floricanes.

Blackberry plants are classified by cane form into three groups: erect, semi-erect, or trailing, referring to how the canes grow and how much they tend to flop. They all provide delicious berries but differ in growth habit and trellising needs. Blackberries, like other fruits, are available with different maturity times and are classified as early, mid, or late season. Many varieties do well in USDA zones 5-9.

This year, at Seeds ‘n Such, we are offering five varieties of thornless blackberry live plants to choose from!

• Natchez: early season, semi-trailing form.

• Arapaho: early season (one of the first to ripen), erect form.

• Ponca: early season, erect form.

• Triple Crown: mid to late season, semi-trailing form.

• Osage: midseason (after Natchez), erect form.

What makes a blackberry different from other berries?

Blackberries are bramble fruits, together with black raspberries and red and yellow raspberries. Some naming conventions include almost 200 other types of berries under the umbrella term 'bramble,' including thimbleberry, salmonberry, and cloudberry. 

While it is fairly easy to tell a blackberry from a red or yellow raspberry, many gardeners get tripped up identifying a black raspberry from a blackberry. After all, they are both deepest burgundy or black, sweet, and grow on canes.

To correctly identify a blackberry from a black raspberry, start with the fruit. In my opinion, a large blackberry is thumb-shaped, while a black raspberry is round like a red raspberry. But, for smaller berries, this isn’t always as reliable. Look at the core or center of a harvested berry. The core of a black raspberry is hollow, just like that of a red raspberry. With blackberries, the core stays with the fruit when harvested, so the berries don’t appear hollow or cup-shaped.  

How to Plant Blackberries

Choose a site for your blackberries that receives full sun for at least 6 hours per day and is well-drained. Many problems with blackberries are due to root rot caused by poor drainage. If your soil is heavy clay, consider creating a raised berm to plant them in, or amend your soil with plenty of compost to help. Avoid areas where water collects in winter or after heavy rains. 

Blackberries will do best in slightly acidic soil with a pH of 6.0-6.8. If your soil is slightly outside that, don’t worry. But if your pH is far out of that range, you’ll want to amend it before planting.

Keep live blackberry plants cool after they arrive. They may be dormant, meaning they don’t have any leaves yet. You’ll want to get them in the ground as soon as possible.

• Soak the roots for several hours prior to planting. 

• Remove all sod and weeds and loosen the soil with a garden fork.

• Space plants about 3-4 feet apart. If planting more than one row, leave enough space, 6-8 feet or more, so you will be able to get between the rows in summer when the canes arch and spread. 

• Dig a hole large enough to spread out the root system and set the crown about 2 inches below the soil line, or at the same depth it was growing in the nursery. 

• Backfill the soil around the roots, applying gentle but firm pressure to remove any air pockets. 

• Trim down any existing canes to within a few inches of the soil line.

• Water your new plants thoroughly, and apply a 2-3 inch thick layer of mulch to reduce weed pressure. 

• Wait until new growth has emerged, about 3-4 weeks, before applying an initial fertilization.

Growing Blackberries

Blackberries don’t need a lot of care beyond an annual pruning, and when grown in a suitable site, will keep providing heavy crops of fruit for years. 

In fertile soils, blackberries won’t need any supplemental fertilizers. A layer of compost as a top dressing in spring, before the new canes emerge, is sufficient. For less fertile soils, apply a balanced fertilizer product like 5-5-5. Two applications a year, one in spring as new growth emerges and the second just after harvest, will be sufficient. 

During the first year after planting, water blackberries weekly unless you’ve received sufficient rain. In subsequent years, regular irrigation isn’t normally necessary, however during dry spells, providing an inch per week of supplemental water will aid fruit development. If in doubt, stick your finger into the soil as deep as you can near the base of the plants. If it feels dry and dusty, give each of them a long drink.

Keeping blackberry canes under control

Blackberry plants can get a bit out of control when left on their own. Keeping them trained and properly pruned will not only improve their health but also make it easier to harvest those tasty berries. 

While erect varieties of blackberries can be grown without a trellis or support, all blackberries will be more manageable and easier to harvest if given some sort of structure to grow on. A simple wire and post trellis can keep vines from collapsing into the lawn under the weight of fruit, prevent breakage during storms, and maintain a manageable berry patch. 

How to prune blackberries

Blackberry floricanes die back after their second year, and won’t come back. But, unlike an echinacea or a bee balm stalk, blackberry floricanes are quite woody and stiff, and won’t just disappear after the winter. They need to be pruned and removed.

In late winter, prune out all dead floricanes (if you didn’t do it last fall). They’ll be brittle and gray, rather than healthy green or brown. Snip them off as low as you can. This is also the time to remove any damaged canes and to reduce crowding. Prune back the remaining canes, leaving 4-6 vigorous canes per plant. Remember, the canes present in late winter are the rising generation of floricanes that bear fruit. More primocanes will pop up in spring. 

If desired, you can also trim side branches on the remaining canes to about 12 inches in length. This pruning will result in larger fruit, although fewer berries overall. It’s up to your preference.

In summer, pinch off the growing tips of the new primocanes when they are about 3-4 feet tall. Like with other plants, pinching the growing tip encourages more side branching, which will provide a heavier yield of fruit the second year.

Harvesting Blackberries

Now that they’re growing well and covered in fruit, when is the right time to harvest?

Blackberries begin as hard little green berries. As they ripen, they enlarge, then turn pink and red before finally becoming burgundy and then black. Not all the berries on a cane will ripen at the same time.

After they turn black, they’ll still be shiny. In another day or two, the berries will begin to lose that shine and look dull instead of glossy. That’s when it’s time to start berry picking. When ripe, the fruit comes off the plant easily, slipping free when given a light tug with two fingers. If you have to yank, it isn’t ready yet. 

Some gardeners like their berries a bit less ripe, while others want them super sweet and don’t mind if they’re on the verge of softening. A few tasty trials will help you refine exactly what your preferred ripeness looks like on your cultivars.

Harvest blackberries in the morning if possible, after the dew has dried but before the heat of the day. Any that won’t be used fresh should be refrigerated immediately. Spread them out in a dish so they are only 2-3 berries deep and they’ll keep longer. If you can’t use them within 3-4 days, blackberries can also be frozen for later use in baking, smoothies, syrups, and toppings.

A healthy blackberry patch will often provide a harvest every couple of days for up to three weeks. To extend your harvest, plant two or three varieties with different maturity timeframes.