Why do some blackberries taste bitter?
Written by
Tina Carter
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Bitter blackberries frequently are the result of timing errors in the harvest or issues in the growing conditions. Picking the berries too early results in bright, sharp flavors when the sugars have not yet developed. Insufficient sunlight will lead to an inadequate amount of sugars being formed. The nutrients in the soil are also an important factor in determining the taste of the berry.
Harvest Factors
- Wait 4-6 days after berries turn black before picking
- Test sweetness with refractometer aiming for 12-18°Bx
- Harvest in morning coolness when sugars concentrate
Sunlight Issues
- Ensure plants receive minimum 6 hours direct sunlight daily
- Prune surrounding trees blocking morning sun exposure
- Use reflective mulch to increase light penetration
Nutrient Solutions
- Test soil annually to correct calcium/magnesium imbalances
- Apply potassium sulfate during flowering for sugar development
- Avoid high-nitrogen fertilizers that promote leafy growth
Proper Harvest Timing: Pick the fruit at just the correct time to sidestep the unpleasant bitterness common to under-ripe berries. Berries require 4 to 6 days following the time they've turned black to develop their sugars. I check every day during the height of the season for ripping. Ripe berries will slip easily from their base and leave no stem behind. I taste a couple random berries the day before I begin harvesting.
Maximize exposure to sunlight during the season. Morning sun is essential for sugar production. Prune the branches above plants blocking the sun. Move container plants to expose them evenly to sunlight. Northern gardens should be positioned to receive southern exposure.
Fix nutrient imbalances using soil tests and specified amendments. Excess calcium inhibits the absorption of potassium. Too much nitrogen encourages plant growth rather than increasing sugar in the fruit. Use proper organic fertilizers based on tests to fine-tune nutrient levels.
If the bitterness lingers, select naturally sweeter varieties. 'Natchez' and 'Ouachita' score consistently high for sugar content. Don't plant older varieties like 'Brazos' that are known for their tartness; sample varieties at local nurseries before committing to planting.
Read the full article: How to Grow Blackberries Successfully at Home
