Growing Raspberries, part 2

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While one can usually pick up a container of fresh raspberries at the grocery store, there is a great deal of satisfaction for me in seeing those berries, just bursting with flavor and juiciness, hanging heavily on the canes. There is a little work involved in getting those berries to produce in your garden, though.

Last week, I talked about raspberry varieties for northern gardens and some general raspberry knowledge that is useful to the home gardener. In this article, I'm going to talk about planting those raspberries.

As with most plantings, the key to success is starting with the proper site and good soil preparation. Raspberries like a sunny, well-drained location. They prefer sandy loam rich with organic matter, and a pH range of 5.5 to 6.5, or slightly acidic. That said, they do very well in my moderately alkaline clay soil. The key is to keep them in a location where water drains away, rather than sets and makes for soggy soil, and to keep the proper levels of organic matter in the soil. In clay, approximately 5% organic matter is a good range. In sandy soils, you can get by with about half that amount.

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I keep the organic matter in good supply by adding a top-dressing of about two inches of well-rotted sheep manure or other high quality compost each fall. I don't use horse or cattle manure on the perennial fruit and vegetable beds. Sheep digest any weed seeds they consume and render them unable to germinate. Other animals do not have that ability, and there is nothing worse than an infestation of Canada thistle or bindweed in your raspberry patch! The bags of composted manure that you can buy at garden centers are generally hot composted, which dramatically reduces the weed seed population that can sneak into your garden.  They are pretty safe to use, regardless of the source animal.

Adding organic matter and tilling it in for a year or even two years before you plant is helpful in incorporating the organic matter and also getting rid of any weeds that may be in the area. Having the soil tested if you don't know how much organic matter your soil contains or what the pH is might save you a lot of headache in the future. You can obtain instructions and soil test kits from your local land grant university extension office. They will even tell you what you need to add to make your soil the best it can be!

You should also stay away from garden plots where you have grown tomatoes, potatoes, peppers, and eggplant within the last four years. These plants can all harbor verticillium fungi that loves to attack raspberry roots.

I should mention, too, that while it is not a key to successful raspberry growth, there is one other thing to remember in choosing your site that is the key to not wanting to pull your hair out when you find raspberry suckers in the middle of your formal perennial garden (or any place else you don't want them). And believe me, pulling your hair out just might be easier than getting rid of rogue raspberry roots. Choose a site that gives your raspberries room to spread their roots, and where you can easily cultivate or otherwise eradicate unwanted raspberry suckers.

If you are planting more than one variety of raspberry, it is advisable to keep black raspberries separate from red or yellow varieties to minimize the spread of diseases. Black raspberries are more likely to carry these diseases, and they are very attractive to the aphids which carry those diseases from plant to plant.. If you have no space to keep them separated, you can do the next best thing by planting the black raspberries downwind, based on your prevailing wind direction at the planting site. This will keep the aphids from being blown to your other raspberry varieties as easily.

Red and yellow varieties can all be planted together, however, if you want to keep your varieties separate, you will want to give them plenty of space. If you plant multiple varieties close together, over time they are likely to become indistinguishable from each other, and the more aggressive varieties will choke out the less sturdy plants.

If you have friends or neighbors who grow raspberries, you probably know someone who is willing to give you some starts. This is tempting, but it can also be risky. This is tempting, because, after all, who can resist free plants? But this is risky because those plants are much more likely to harbor hidden diseases that they will bring into your patch. I recommend that in this case, you spend the money to buy from a reputable nursery or grower who can guarantee that the plants you receive are disease free and "virus-indexed". Raspberry mosaic viruses can devastate your patch and older plants from home gardens are much more likely to harbor these diseases.

Raspberries should be planted in early spring, after all danger of killing frost is past. About two weeks before you plant the raspberries, spread some 10-10-10 fertilizer over your planting area and till it in. You should apply enough to provide about two pounds each of nitrogen, phosphorus, and potassium per 1000 square feet of planting area. I like to till the soil again immediately before planting, to break up any clods that may have formed and to nip off any brave weed seedling that might have tried to get a foot hold.

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Most raspberry starts come as bareroot. They like moisture, so it is a good idea to wet the roots well before sticking them in the soil. This can be accomplished by soaking them in a bucket of water for an hour or two. I prefer a little less "wet" so I like to moisten newspapers well and wrap them around the roots. This way, I can also gently separate the roots and wrap the plants in their own individual paper while I have them in a protected area.  I don't have to pull the whole clump out of a bucket of water and mess with the roots while they are exposed to the sun and wind. I keep the newspaper in place until I am ready to put the root into the ground, leaving the roots to have much less exposure to drying elements before planting.

Raspberries can be planted in rows or hills, depending on space and your personal preference. If you plant in hills, you will want to leave ample space on all four sides of each hill to be able to cultivate with whatever equipment you plan to use. If you plant in rows, bushes can be spaced about two to three feet apart within the row, but the rows should be far enough apart to easily pick between and to run whatever cultivating equipment you plan to use between the rows.

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Set the roots firmly in the soil, keeping them at the same depth they were in the nursery when they were dug, or that they are in the pot if you are planting potted starts.  Pat the soil firmly around the roots and water well.  Trim the canes back to about eight to ten inches. Water well, and keep uniformly moist throughout the growing season.

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Red raspberries will spread from suckers that grow up from both the crown and the roots.  Those suckers will grow together to form a solid hedgerow, whether you plant them in rows or hills. They should be cultivated periodically to keep the base of the hedgerow no more than 12 to 18 inches wide to facilitate picking and pruning. Black and purple raspberries send out suckers only from the crown of the plant, so they do not form hedgerows. They are more easily maintained in hill plantings than red raspberries, and the hills should be planted about four feet apart.

Most raspberries do best with some sort of support. In the next blog installment, I'll talk about trellising, pruning, and other maintenance for raspberry plants.

Growing Raspberries

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There is nothing better than wandering across the grass, climbing over the little rabbit fence, and reaching for a plump, juicy, sun-kissed raspberry. If a little juice runs down my chin when I bite into that luscious berry, so much the better. Add to that the fact that raspberries are highly nutritious - packed full of Vitamin C, fiber, and antioxidants - and you just might have the perfect back yard fruit.

Raspberries are relatively easy to grow, and with a little care, you can have home-grown raspberries for a good long time. There are two types of raspberries: summer- bearing, and ever-bearing or fall-bearing.  Summer bearing produce one large crop per year in the summertime on last year's canes and ever-bearing or fall-bearing produce on both last year's canes and the current year's growth, so you can harvest two crops, one in the summer and one in the fall.

Summer-bearing varieties usually begin producing in early summer and produce for about two to four weeks. Fall-bearing varieties typically begin producing in mid-summer and produce up until a killing frost, or in the case of this past year when a killing frost came very late in the season for us, until the shorter days of autumn and winter in the north country discourage further fruit set.

Raspberry roots are perennials, which mean they come back year after year in their hardiness zones. The canes, which grow from buds on the root, are biennial, which means each cane lives for two years. Some raspberry varieties produce fruit on the canes the first year of growth; others produce fruit only on canes that are two years old.

Those which produce fruit on the canes the first year are called "primocane" raspberries, and are also identified as "fall-bearing" because fruit ripens late in the season. You can harvest fruit from those varieties the first year of planting, the first crop generally in July or early August, and the second crop later in the fall.  The first year canes become "floricanes" or second year canes the next growing season, and they will produce a crop again in early to mid-summer, but it is usually a marginal crop at best. Many growers prune all the canes down in the fall so that the next year's growth is all primocane, helping the raspberries to produce better.

An old standby primocane variety for zone 4 and warmer is "Heritage". Heritage produces large crops of good-sized berries that are good for eating fresh, freezing, canning, jams and jellies.  "Anne" is a yellow-fruited variety that has a hint of an apricot taste. Anne is good for eating fresh and freezing, but is not the best for canning or jams and jellies because it does not retain a nice color when heated. "Polana" is similar in taste and color to Heritage, but the fall crop ripens several weeks earlier, so it may be a better option for those areas where killing frosts come earlier in the fall. Polana is rated hardy to zone 3, so it is one of the hardiest of the primocane raspberries. Another earlier ripening variety hardy to zone 3 is "Autumn Britten".  Other zone 4 hardy varieties include "Polka", another Polish variety similar to Polana; and "Joan J", an early producer that has the distinct advantage of being borne on a thornless bush. "Caroline" produces a nice, large berry with an intense flavor. I find that this variety, while rated for zone 4, needs to be in a very sheltered location or have the root mulched in the winter. "Himbo Top" produces very large, deep red berries that hold their color better than most varieties. It is a favored variety for farmers' markets and roadside stands for that reason.

"Heritage" raspberries (internet photo)

"Anne" (internet photo)

Raspberry varieties which produce fruit on two year old canes are called "floricane" raspberries. The first year of growth on the canes will be only vegetative - there will be lots of green leafy growth, but no flowers or fruits. The next year, those canes will bloom and set fruit, while new vegetative canes begin to prepare for the next year's fruits.  There are more zone 4 and colder varieties of floricane raspberries than there are of primocane, and the nice thing about those varieties is that they come in early, mid, and late season fruiting, so you can extend your growing season significantly with a selection of several varieties.

Boyne is an early season floricane variety that is hardy to zone 3. It produces good amounts of nice, sweet berries that make excellent jam.  They are not a real firm berry, so must be handled carefully in picking and storage. Prelude is another early season variety hardy to zone 4 with excellent flavor, but also not a real firm berry.

"Killarney" (internet photo)

Killarney is an early-mid season producer that is a little finicky about growing in colder climates. I like the fact that it has very sturdy canes that stay upright even when loaded with fruit, making the berries easier to pick (and I am all about anything easy). Killarney has been around since the early 1960s, and while it is a zone 4 hardy variety, it has done well in my zone 4 but sometimes zone 3 climate. It does benefit from a protected location.

Latham is a North Dakota favorite and is really the workhorse in my berry patch. It is a mid-season fruiting variety that was released by the University of Minnesota in the 1920s and has been a favorite of home gardens ever since. The fruit is medium size and a light red that turns a deep burgundy color if overripe. Lack of cohesion of the drupelets (the little round balls that cluster together to form the berry itself) is a problem with Latham, but for jams and jellies, which are excellent when made from Lathams, that is not a problem.

Nova is another mid-season variety that was released from a breeding program in Nova Scotia in the early 1980s. Nova is tolerant of both extreme cold and heat, reliably hardy to zone 3, and is a heavy producer of medium to large red berries that have a longer fresh storage life than many other varieties. It also has the advantage of having fewer thorns than most varieties.

Encore is a late mid-season producer of large, firm red berries excellent for canning and freezing that grow on sturdy, nearly thornless canes. Now, if you have ever picked raspberries, you have a pretty good idea of why I am telling you about thornless and nearly thornless canes. While I love my Lathams, I hate that I have to pick those microscopic little thorns out of my finger tips for days afterwards.

There aren't any red raspberry varieties that are reliable producers for late season summer bearing in northern climates. Royalty is a purple variety that does ok in protected areas of zone 4, producing large, purple berries in August. The bushes are very prolific and will need trellising to stay upright.

Black raspberries are not as hardy and will need winter protection in anything colder than zone 5. Black raspberries should be planted separately from red and yellow varieties, as they are a closer relative to the wild varieties and tend to be more susceptible to pests and disease. Jewel is one of the hardiest black raspberry varieties.

In the next blog installment, I'll write about planting and care of raspberries.

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