One of the first things I do in spring, way before fleas hatch, is clear off all the debris in the yard and toss it in the compost pile, which as the materials break down heats up to a point that kills any eggs or seeds within it. I leave native plants standing for wildlife through the winter, but in spring it’s all taken down, even mowed if possible, then raked in order to remove possible pest habitat (including plant diseases which may have overwintered). If you don’t have a compost pile you can throw the material away in a bag, but just don’t keep it around, piled in a corner, or it can become a breeding ground for everything that laid eggs in it last year. This helps immensely with reducing the initial populations and you’ve also destroyed a lot of eggs and habitat for many insect pests.
This also helps to delay the onset of fleas in your yard, but they’re going to start hatching some time regardless of chemical or organic controls, so be prepared with methods to manage flea populations through their life cycle.
Manage Areas Fleas Prefer
To start with, try to minimize or eliminate damp and densely shaded areas in your yard—underneath a shrub, for instance, often a favorite place for pets to hang out on hot days because it’s cooler and the soil is a little damp. It’s absolutely flea heaven, especially if you’ve either left the leaf litter from last year or added some decorative bark or wood chip mulch. This one area can support three stages of the flea: eggs can be laid here, the larvae can live on organic matter, and they can build their cocoons here as well, hatching into adult fleas that feed on your kitty taking a nap in the shade.
My yard tends to be very damp and I also have a slug problem (that’s an understatement), and for years I’ve sprinkled diatomaceous earth (DE)in all the moist shady areas for the slugs that feast all night, also taking care of a good many fleas. This product is not soil at all but the shells of diatoms, tiny sea creatures, crushed to a fine powder. Sea shells are actually formed of minerals and while the powder looks like dust it is actually very tiny, very sharp particles that cut into the exoskeleton of the flea, causing it to dehydrate and die. It does the same thing to slugs, but other creatures, from earthworms to birds, simply digest it with no ill effect, and it’s completely a physical effect with no chemical effect at all.