The International Herb Association has made a rather unusual choice for their 2020 Herb of the Year. Instead of what we typically consider herbs – basil, lavender, oregano, thyme, etc. – raspberries and blackberries have been given this year’s honor. And that’s not all. The entire Rubus species, which numbers in the hundreds, is included. So also receiving the tribute are boysenberries, thimbleberries, loganberries, black raspberries, marionberries, dewberries, tayberries, wineberries, cloudberries, salmonberries and many more, some of which are not winter hardy in Wisconsin.
Plants in the species Rubus are known as bramble fruits or cane fruits. Obviously, I can’t fit information on each of these plants in this column space, or do justice to even one of them, but here’s an introduction to raspberries.
Raspberries are perennial plants, and the roots and crowns live below ground for years. The above-ground parts, the canes, live for only two years.
Raspberries are classified as either summer-bearing or fall-bearing. Summer-bearing raspberry canes produce only leaves their first year. The second year, the canes flower and bear fruit, and then die back. In contrast, fall-bearing raspberry canes bear fruit the first autumn and then a small crop the next summer before dying back. New canes sprout from the below-ground crowns each year so there is always a mix of first- and second-year canes in a raspberry patch.
Raspberries need a sunny spot in well-drained, slightly acid soil. They need to be well irrigated though, especially in sandy soils. The area should be kept free of weeds.
Purchase dormant raspberry crowns from a reputable nursery in spring. You’ll likely receive a clump of roots with a cane or two that may or may not have started to produce leaves depending on when you buy. Set the plants in a hole slightly deeper than they were originally grown. You should be able to determine this by looking closely at the cane. Gently spread the roots out, pack the soil firmly around them, and water well.
People are often confused about how and when to prune raspberries, but it’s really quite simple. Use a hand pruner to snip canes as close as you can to ground level after they fruit their second year. You can tell which canes produced fruit by looking at them. Those that have fruited are woody in appearance while first-year canes are still green.
A second pruning is done in winter when the canes are dormant. Often first-year canes have grown way too tall and unruly. Cut the tips back by one-fourth to one-third. Only a small amount of crop will be lost by doing this and the pruning will stiffen the canes and result in more fruit growth lower on the stems.
For everything you need to know about growing raspberries in Wisconsin, see https://learningstore.extension.wisc.edu/ and enter A1610 in the search box at the top of the page. You can purchase a paper copy of the document or view it online for free.