Failure To Thrive

This does not look like a pest or disease but more a “failure to thrive” situation. There might be several things going on here. First of all, the level of the soil is very low. How deep is the soil in this box? It looks like it might only be four inches or so, and this isn’t enough to support good plant growth. Be sure to fill all containers to within an inch of the top, and don’t put anything else in the bottom: no rocks, shards, or other “filler” no matter what your mother or neighbor told you.

Secondly, are there drainage holes in this box? Every container should have holes for the excess water can drain out. Cosmos, which you have planted here, need good drainage.

Thirdly, was any time-release or liquid fertilizer used? Annuals need “fast food” so either a time-release product or synthetic liquid are important. Ask your local independent garden center for recommendations.

Finally, are these boxes in full sun? Cosmos need at least 5 hours of dead-on sun to flower well. If these boxes get less, use New Guinea Impatiens or begonias instead.