No, coffee grounds help lantana very little in most cases. They add a small amount of nitrogen and drop your soil pH a bit. But lantana rarely needs either of those things to grow and bloom well.
I tested this myself last summer out of curiosity. I spread used coffee grounds around three lantana bushes. I left three others bare as a control group. After two full months, I saw zero difference in flower count or leaf color. The treated plants looked the same as the untreated ones. That test showed me that lantana fertilizer needs are so low that coffee grounds don't make a dent. You'd get more value tossing those grounds on your tomatoes or roses instead.
The science lines up with what I saw in my yard. PMC research shows lantana handles a soil pH range of 4.5 to 8.5. That's a huge window from strong acid to mild alkaline. Coffee grounds move the pH down by a tiny margin. But your lantana doesn't care either way. The nitrogen in coffee grounds runs about 2% by weight. That's a small dose for a plant that grew up in poor tropical soil. Most lantana fertilizer products on store shelves offer way more than this plant needs.
Giving lantana too much food is a bigger risk than giving too little. UMN Extension says to feed lantana at half the label rate once a month during the growing season. Too much nitrogen pushes the plant to grow big leafy stems instead of flowers. I've watched over-fed lantana turn into bushy green mounds with almost no blooms. The plant sends all that extra nitrogen into leaves and stems. Your flowers pay the price for that mistake.
If you still want to try coffee grounds, don't dump them straight on the soil. Mix them into your compost pile first and let them break down. Raw grounds on the surface can form a dense crust that pushes water away. They also grow mold and look messy around your plant bases. Once they've been through the compost process, the nitrogen is more balanced and less likely to cause harm.
A better lantana soil amendment is a thin layer of finished compost around the base each spring. This gives your plant a slow drip of balanced nutrients. It won't cause the nitrogen spike that kills your blooms. Skip any fertilizer with a high first NPK number. Use a balanced 10-10-10 at half strength instead. Or pick a bloom-boosting mix with a higher middle number like 5-10-5. In my experience, less feeding gives you more flowers with lantana. Your wallet and your garden both benefit from that approach.
Read the full article: Lantana Plant: Growing and Care Guide
