Star Jasmine Not Spreading After Preen? Here's Why and What to Do

Understanding Preen's Effect on Established Plants

Many gardeners worry that Preen weed preventer harms their existing plants. The good news: Preen is a pre-emergent herbicide that only stops seeds from germinating. It does not affect established perennials like star jasmine (Trachelospermum jasminoides), nor does it damage existing roots or foliage.

Why Your Star Jasmine May Not Be Sprawling

If your star jasmine isn't spreading as expected, the cause is likely cultural rather than chemical. Star jasmine thrives with:

• Full sun to partial shade – at least 4–6 hours of direct light for best growth.
• Well-drained, fertile soil – amend with compost or well-rotted manure annually.
• Consistent moisture – water deeply during dry spells, especially in the first few years.
• Spring feeding – side-dress with well-composted manure each spring to encourage vigorous growth.

No Need to Replace Soil

Preen breaks down over time and does not persist in the soil at levels that harm established plants. Simply focus on optimal care: mulch to retain moisture, fertilize organically, and ensure adequate sunlight. Your star jasmine should resume spreading once its needs are met.