What are the best methods to prevent algae growth on north-facing stone planters?

Algae growth on north-facing stone planters is a common issue due to limited sunlight and moisture retention. To prevent algae, start by ensuring proper drainage to avoid water accumulation. Regularly clean the planters with a mixture of water and vinegar or a mild bleach solution to kill existing algae. Applying a sealant to the stone surface can also create a barrier against algae formation. Additionally, consider using algae-resistant plants or placing the planters in slightly sunnier spots if possible. For a natural approach, sprinkle baking soda on affected areas to inhibit growth. Consistent maintenance and these proactive steps will keep your stone planters algae-free and visually appealing.