My Grapes Won't Ripen

Sunlight

• Many home grape growers erroneously believe grapes require sunlight on their fruit to ripen. Grapes actually require plenty of sunlight on their leaves in order to produce the sugars necessary to sweeten and thereby ripen their fruit. Prune trees or bushes that are shading your vine, and ensure it is getting several hours of direct sunlight through the day. These changes may not help you until next year's harvest, but you'll be just as impatient for a batch of your own grapes then, so get to work.

Water

• Grapevines, like most plants, need water. Grapes do not like to have standing water around their trunks, however, so you should plant your vine in well-drained soil. Overwatering can cause your fruit to burst before ripening, or become small sacks of flavorless water. Underwatering can also delay fruit ripening, so ensure your vine is planted on a south slope, with well-drained soiled, and is being watered daily.

Soil Quality

• The soil surrounding your grapevine should be well drained. Additionally, it must be sufficiently nutrient-rich to encourage vine growth and loose enough for your vine to spread its roots. Mulching your vine with manure each spring or late winter can help ensure the soil is well fertilized. During the off season while the vine is dormant, usually from first frost to mid-February, you can also till the soil around the vine to keep it aerated and conduce your grapevine to spread out its root system.

Temperatures

• Grapes require high temperatures to ripen. Unfortunately, even vineyards experience years in which unseasonably low temperatures negatively affect fruit production and ripening. There isn't much that can be done about local weather issues; however, choosing a cultivar that is suited for your zone or region can help minimize the damage done to crops by local temperature fluctuations.