Answer: Your plant problems sound as though they're cultural, so let's try to figure out why. Finished compost will retain some of the characteristics of the raw materials used in the composting process. If your community collects roadside plant debris, there's no telling how much chemical contamination it contains from neighborhood use of herbicides and fertilizers. While most of these products will bio-degrade during the composting process, and will be perfectly safe to use on woody ornamental plants, there may very well be some residual effect on tender annuals and perennials. It could also be that the mulch is holding too much moisture and excess heat, and your plants are reacting to the stress of the situation. All annuals and perennials benefitfrom deadheading the spent blooms, and from pinching to promote new growth, so your treatment of the sickly plants is definately doing some good. Just be sure to dispose of the debris rather than leave it laying around in the garden. Just to test the theory, try to find another source of organic material to use around your perennials this season. Then you'll know for certain in the compost is the culprit and can avoid using it around tender plants.
Q&A Library Searching Tips