|Heritage raspberries in August - just before berries are fully formed for the fall|
This article will address Fall bearing or "everbearing" raspberries.
There are two ways to prune them - one way allows for a harvest in mid summer and a harvest in the fall. The other way allows for a harvest in the fall only.
I prefer to harvest in the fall only for a few reasons -
1. It eliminates many of the airborne fungal diseases that tend to build up by fall and limit summer production.
2. It results in a much larger harvest in the fall.
3. I also own summer bearing raspberries so I get a continuous crop either way.
4. It's so much easier!
Here is my interpretation of the Heritage (everbearing) raspberry lifecycle and and when to prune out the old canes for a double harvest and a single harvest.
Year 1: New GREEN shoots will pop out of the ground and begin to grow. These are primocanes (or first year canes.)
Those green canes will continue to grow throughout the summer and will be over 3 feet by fall. If you are growing heritage, they are able to stand up without support and do not bend over.
In the fall, the plant will bear raspberries on the top of the cane. See my photo at the top of this post to see what I mean. My drawings are not to scale.
In the winter, the green foliage will die down and the plant will go to sleep for the winter. Leave it alone.
Year 2: Once the snow is gone, and things have started to wake up, you will find a big brown stick that should start to grow leaves along it's sides and a new green shoot (most likely multiple green shoots) popping up out of the ground.
These green shoots will follow the Year 1 Cycle.
The brown canes are now 2 years old (floricanes) and will follow the plan for Year 2.
The tips of the cane where berries grew last season will die. It will either snap off or shrivel down. You can and should cut this tip off. Leaving it only invites disease.
In the summer, the brown canes should be fully leafed out and will make berries along the side branches. In zone 4, berries start ripening around the 4th of July.
After it has produced berries, the floricane (year 2 cane) will begin to die. The leaves will yellow, then brown, then fall off. You may cut it out, all the way to the ground, at any point after it has finished making berries.
The roots will stay in the ground and send up new primocanes in the spring. Leave the year 1 canes alone and allow them to make summer berries next year.
This repeats for at least 10-20 years. By then, your plants might be crowded, diseased, or just out of steam. You can take the new shoots in the spring and move them to a new location. They are a new plant and will have 10-20 years of life ahead of them.
When the plant is finished making berries (about the end of October in zone 4), cut the cane down to the ground. Your berry patch will look empty, but will come back to life in the spring.
**When you cut down old canes, you should burn them or remove them far away from your berry patch. Why? Because beetles, worms, and other ickys that you don't want in your berries will live inside them and then move into your healthy berry plants!
You can compost them, but in my experience they take forever to break down (unless you own a wood chipper) and they tend to invite woodchucks. Woodchucks have scavenged through my compost bin in the past and were seen eating raspberry canes!
If you burn them - wood ashes are great for asparagus and lilac bushes. You can even give some of it back to the raspberries if you don't already have a ph that is too high. Asparagus and lilacs will appreciate them more!