How to Prune Boysenberry Plants
It’s finally a beautiful, rain-free weekend in January! Therefore, it’s the ideal time to prune boysenberry plants as well as roses and most fruit trees. Today I’m sharing what has worked for us as far as pruning our thornless boysenberry plants here in Southern California.
Growing Thornless Boysenberries in zone 10b
Our home isn’t far from the infamous Knott’s Berry Farms amusement park, and the city where boysenberries were created. There is a lot of interesting history there, but in the interest of getting this article and video tutorial out soon for all my fellow SoCal gardeners, I’m going to cut right to how we prune our boysenberry plants. After reading this blogpost, make sure to watch our YouTube video that we filmed while Sam pruned our boysenberry plants this year.
A little backstory: we have had our thornless boysenberry plants for over three years now. The first year gave us a few berries, and we did not prune our boysenberry vines because we didn’t know anything about it. The second year, the boysenberry plants took off and set TONS of delicious fruit. I made our first ever homemade boysenberry pie, and committed ourselves to doing a proper pruning that Winter. After that proper pruning, the boysenberry plants went on to have an incredible bumper crop last Spring….and here we are about to follow those same procedures in hopes of another wonderful harvest this Spring.
If you’re looking for great, semi-local plants, we purchased our thornless boysenberries from the CalPoly farmstore. We have three plants in our garden, growing along an odd DIY trellis that was originally meant for something else entirely—that’s a whole other story! See our Cattle panel Trellis build here!
Tools for pruning boysenberry plants
Boysenberry vines aren’t as thick or woody as some fruit tree branches, so you can get away with just a good pair of hand pruners/secateurs to prune your boysenberry plants. Personally, we keep a whole set of pruning tools in our garden shed that covers pretty much all the situations we might find ourselves in. I pulled this tool list from my article on Getting Started Growing Roses but I think any gardener would benefit from having these main tools ready to go:
Best tools for pruning plants:
Manual Hand pruners or secateurs– I use these most often. They can handle most plants, smaller stems, and are hardier than herb scissors.
Loppers– A MUST for thick branches, especially when pruning climbing roses and fruit trees. The long handles help with reach as well.
Folding hand saw– this one I rarely use for roses, but it is a MUST in my fruit pruning toolkit. We often have branches that are too thick for the loppers to handle, and this hand saw works perfectly. This year we also found it handy for sawing down an old banana trunk.
Garden gloves– I don’t think there are gloves out there that will perfectly protect you from thorns, so you still need to be careful, but a good thick pair of garden gloves is really necessary.
Eye protection– whipping branches, getting into thick canopy, and falling debris are all reasons to wear eye protection. Especially when pruning our fruit trees and climbing roses, it’s just better to be safe
Don’t forget to sanitize all pruning equipment between different trees/plants, etc. and before starting to prune. This can be done with a simple disinfectant wipe or whatever you prefer.
Boysenberry old growth versus new growth
The number one thing that you need to know before going to prune your boysenberry plants, is how to determine which branches are the old growth and which are the new growth. For old growth, it’s pretty simple to look at the branches and see the dead sets of berry clusters/expired flower ends that would indicate that fruit was picked off a particular branch. Essentially, we want to follow these branches that fruited last season alllll the way down to the crown of the plant and cut to remove. Your boysenberries will not fruit on the same branch twice, so the first thing I like to do is clip off all old branches (that have fruited last season). Afterwards, you’ll be able to have a better view of what remains and finish the pruning process (don’t forget to watch our video tutorial for further clarification).
Identify rootstock/sucker branches
Occasionally thornless boysenberry plants produce a thorned rootstock. Since ours should be thornless, this next step for pruning boysenberry plants is a little simpler for us. Wherever we see a cane growing that is thorny, we remove it entirely because we know it is part of the rootstock and not part of our thornless boysenberry plant. This idea is similar to “suckers” that grow off citrus or any branches that develop below the graft of a fruit tree, etc. Removing any suckers is a common step in most pruning recommendations.
Next, keep an eye out for any canes that are dead/diseased/damaged on the boysenberry plant. You want to prune those canes off because they won’t be productive and also can be a place for disease to continue spreading. We are almost done pruning our boysenberry plants!
Select new fruiting canes
After you’ve removed all old boysenberry canes (that have fruited last year) and anything dead/diseased, it’s time to select the best canes to produce fruit THIS year. Sam and I have found that keeping 3-4 new canes per plant is perfect for us. In fact, by January you can already start to see buds pushing on these new canes! We like to look at all of the new canes that each boysenberry plant has produced and select the most vigorous looking (ie. thicker, no damage, and longer). It might seem difficult to do, but remove all other canes, leaving only the 3-4 new canes per plants.
Setting your boysenberry up for a great season
After we have pruned your boysenberry, Sam likes to train our new canes onto their support structure by tying them in. You can see more clearly how we support our boysenberry in the video. Now that we have finished pruning our boysenberry plants, I like to top off the area with some compost and berry-specific amendments. In the past we have used different products, but I find that the most important things is to use something specifically for berries. Some great options are: berry-tone, cottonseed meal, and down to earth acid mix.
I hope you found our little write-up and video tutorial helpful! I remember being really intimidated last year when we tried to properly prune our boysenberry plants, but it really felt much simpler this year— especially knowing that our pruning produced a great crop of boysenberries last year. Happy growing friends!