Is there any way to make raspberries sweeter? I have several varieties growing where they don’t get a lot of attention and they produce but not very tasty or sweet berries. More water? Manure?
2 Likes
Do you have any yellow/white raspberries? I find them sweeter.
2 Likes
Now that you mention it, I did plant a couple of yellow ones last year, but no yellow berries 
. Maybe they didn’t make it over the winter. I will try again, thank you.
1 Like
My yellow berries don’t come in until August, but they keep bearing until November. Maybe all you have to do is wait a bit and see. But they do like a lot of water.
1 Like
Many thanks to Milner Gardens & Woodland’s Gardening Advice line (a partnership between Vancouver Island University’s Milner Gardens & Woodland and the Vancouver Island Master Gardeners Association) for the following response:
Thank you so much for reaching out to us at the Garden Advice Line. We are happy to offer you some advice on why your raspberries are not as sweet as you would like.
Raspberries require a minimum of 6 hours of sunlight per day but would prefer 8 hours.
Raspberries like well drained, moist soil and don’t thrive in an inconsistent watering environment. Often overwatering can produce very bland raspberries.
In late winter, early spring amend the soil in your raspberry patch with a slow release low NPK fertilizer in an 8-8-8 or 4-4-4 formulation. Gaia Green 4-4-4 is a good organic fertilizer that is gentle and will not burn the plants. Never add too much nitrogen.
Composted manure as well as just compost are also reliable sources for nutrients. You can also increase the soil organic matter content by adding a layer of leaves in the fall as well as chopping up the dead canes when you prune them out and leaving them on the soil. All of these will decompose and improve the soil.
Mulching is essential to help regulate temperatures, protect the soil from pounding winter rains, and control weeds, all the while adding nutrients back into the soil as it decomposes. Arborist wood chips is an excellent choice for mulch.
Pruning: (for summer bearing types)
Method 1 - In late winter or early spring, prune all canes (or stems) that bore fruit the previous year right to the ground. They won’t fruit again.
Method 2 – As the canes finish fruiting in July, remove each to the ground. This will provide the new growth (which will bear fruit next year) with better air circulation and light. The following spring you can remove any spindly or weak growth.
Raspberries are much easier to tend and harvest if they are kept confined in well-defined rows so remove any canes growing outside the 12- to 18-inch row footprint of the plants
Remove any spindly or very short canes.
Thin the rest of the canes keeping four or five of the healthiest, tallest, and fattest canes left per foot along the entire planting space.
Tie canes to the supports to prevent wind damage, bending over or cracking
It is essential that you keep the rows of your raspberries under 2 feet wide, 18” is better. This allows for better air circulation and more sunlight to penetrate and helps prevent fungal diseases.
Picking:
A day or two can make a huge difference whether a raspberry is ripe or not. If your raspberry resists coming off the stem at all, it isn’t ripe. Color alone is not a reliable guide. Typically, the yellow/gold raspberry varietals are sweeter than the red colored ones. Also, if possible, harvest in the morning and try to avoid picking when fruit is wet from dew, fog or rain, and don’t wash raspberries before storing them. Wet fruit will decay faster.
Research:
To determine which raspberry varieties you want to grow, research their sugar-to-acid ratio. This can often be found in agricultural and food science papers. Tulameen, Cascade Delight or Anne are just a few sweeter variety recommendations. One good resource is found at: Comprehensive Evaluation of 24 Red Raspberry Varieties in Northeast China Based on Nutrition and Taste - PMC
Good luck!
Vancouver Island Master Gardeners
References:
Extension.umn.edu
2 Likes