Jennifer Schultz Nelson
Extension Educator, Horticulture
If you've always wanted to grow fruit in your backyard, but were afraid of the time and effort involved, consider raspberries. Relative to a lot of other home grown fruits, raspberries require a lot less attention.
Among fruits commonly called raspberries, there are a few different species in the genus Rubus. Rubus is the genus also known as the "brambles", which includes raspberries and blackberries. It is considered to be one of the most diverse genera in the flowering plant world, with hundreds of species.
Most red raspberries as we know them are derived from two species—Rubus ideaus, native to Europe and Rubus strigosus, native to North America. Black raspberries are the species Rubus occidentalis. Some consider black raspberries to have superior flavor to all other raspberries. Purple raspberries are crosses or hybrids of red and black raspberries.
Yellow, golden or orange raspberries are typically mutants of red-fruited varieties, although there are a few yellow-fruited mutants of black raspberries.
Raspberries are botanically considered an aggregate fruit. If you look closely at a raspberry, you'll see that each raspberry is a group, or aggregate, of smaller individual fruits called drupelets. The drupelets are attached to a fibrous core called the receptacle, which in raspberries gets left behind when the fruits ripen and are picked or fall from the plant. This gives the fruits a hollow appearance.
In choosing raspberry cultivars for your garden, it pays to know a little bit about how raspberries grow and produce fruit. It gets confusing, but bear with me.
Raspberries are a perennial crop, but the shoots, or canes that grow are individually biennial. That means that each individual cane will only live for two years.
The first year of growth, the canes are called "primocanes". In many raspberry cultivars, the primocanes do not produce flowers and fruit. In the second year of growth, the canes are called "floricanes" and they produce flowers and fruits. If you just let raspberries grow without pruning or cutting back, there would be a mixture of primocanes and floricanes present at any given time.
There are red raspberry cultivars available that are called primocane fruiting or autumn fruiting types. These will flower and set fruit on the primocanes, which means you can harvest fruit from them the first year they are planted. They will set fruit on the same canes in the second year (now called the floricanes), but in general this second crop is of lesser quality.
Recommended pruning for raspberries depends on whether you have primocane (autumn) fruiting or floricane fruiting cultivars. For both types of fruiting, you can choose to just remove the dead canes each year, leaving both primocanes and floricanes intact. Remember that floricane fruiting cultivars must be pruned this way if you want to harvest any fruit—they only produce fruit on the floricanes, so you can't remove those and expect to harvest any fruit!
Autumn or primocane fruiting cultivars may be cut back to the ground after last harvest in the fall. This channels all the plant's energy into producing primocanes the following spring, which for these types yield the best quality fruit. It also reduces the chances of diseases overwintering in plant debris.
Although your neighbor may have a ton of raspberry plants they want to share, the best recommendation is to buy plants that are certified disease- free from a reputable nursery of mail-order company. Raspberries are typically planted while still dormant in the spring.
It pays to take time to prepare the soil where your raspberries will be planted. Some sources recommend you spend the first year just preparing the soil for planting the second year! Raspberries produce best in soils with high organic matter, which may take some time to build up depending on your existing soil. Aged manure and shredded leaves are great sources of organic matter. Also use your soil preparation time to eliminate any perennial weeds that may be present at the site.
As with many plants, raspberries need well-drained soil. They will tolerate a pH of about 5.8-6.5, and prefer a sunny location. They need adequate water, about an inch or two per week for healthy growth, but do not like wet feet. They are shallow rooted and so should be mulched to prevent the roots from drying out.
Because they can be susceptible to verticillium wilt, a fungal disease, the best sites for raspberries should not have had verticillium-prone crops eggplant, potato, tomato or strawberry planted there for the last five years. There are other fungal and viral diseases, as well as insect pests that target raspberry. Good site selection and cultural practices will go a long way in keeping your raspberries healthy. If problems do surface, your local Extension office is a great place to go for advice.
Raspberries can be grown as individual plants, sometimes called hills, or in wide rows called hedgerows. Either way you grow them, you will have to confront their vigorous growth habits. Raspberries like to produce tons of suckers. Thankfully, their root systems are shallow, so they are easy to remove. In my garden, any suckers outside the designated "raspberry area" get removed.
Trellising your raspberries will make harvesting fruits a lot easier. Without trellises, the canes tend to flop on the ground. My husband built simple "T" trellises for our raspberries, using metal fence posts and scrap lumber. We have our "T" trellises about every five feet down the length of our raspberries. He drilled a series of holes in the wooden cross-piece of the "T" and this is where I threaded twine through to hold the canes off the ground. It's not fancy, but it works great.
I have two raspberry cultivars in my garden. Both are primocane, or autumn fruiting types. I grow the red-fruited 'Caroline' and the yellow-fruited 'Anne'. This is the third growing season for both cultivars. Both cultivars produced fruit their first year, but up until this year 'Anne' didn't produce much at all in my garden, and the fruits were tiny.
The books all say this cultivar doesn't produce fruit until August, but mine are fruiting now, and they are relatively large, some almost an inch long. This is a vast improvement over past years—I think the plants are becoming more established, and I have also fertilized each spring as the new growth emerges.
'Caroline' is also fruiting now, but the fruits are much smaller than 'Anne'. Typically 'Caroline' will produce the best, largest fruits in the fall—I can't wait! In an economy where grocery costs are skyrocketing, I love being able to harvest my own produce from my backyard. I encourage you to try it too.