decompose" means "to separate into components or basic elements", "to rot or decay", "to break down (organic matter) or (of organic matter) to be broken down physically and chemically by bacterial or fungal action; rot". It also means "to break down naturally through the action of biological agents". All things decompose sooner or later. Some things like plastics and all of our consumer wastes filling our landfills will take years, if not many centuries to do so.
Hostas and ferns decompose very quickly.
By spring there will be no sign of their leaves in the garden.
These geraniums will provide green and then bronze groundcover until midwinter, then they will start to decompose in preparation for new leaves next spring.
This Russian Sage will hold its stature and brown leaves through the winter, for structural interest until late spring, when the dead leaves will fall, and the new leaf buds appear.
Upclose of Russian Sage frost bitten leaves, and sturdy stalks.
Lavender Cotton (Santolina) will hold its leaves all winter, whereas the leaves of the Coneflower (Echinacea) have already started decomposing for the season.
Ants will look for food here in preparation for the winter.
Blue Mist Spirea holds its seed heads gracefully all winter (this is not invasive where I live!)
Siberian Iris leaves provide winter interest as well as food for the deer
Autumn Joy Sedum seed heads will also look beautiful all winter. Who wants to look at a flat garden for 5 months of the year? Not me.
This wood pile has been "decomposing" now for about 5 years. It is used by the foxes and other wildlife for shelter and security, eaten by ants and bugs, and pecked on by woodpeckers, nuthatches, and other birds.
By spring these native grasses will fall gracefully back into the earth, and new blades will start again.
Thinking about how things decompose, it's helpful to understand what factors help speed or slow the process. Fungi, bacteria, heat, moisture, temperature, and light all play parts in how fast any living thing falls apart. Take our skin for example. Lack of moisure results in dry, cracked skin, which is more prone to itching, and thus provides a way for bacteria to enter, causing disease and/or decay. Too much moisture, and our skin starts to sweat, get oily, and need washing to keep the bacteria at bay. Too much light, and our skin becomes sunburnt and and shows its' decomposing age quicker. Too little light, and fungi thrive, spreading disease.
Plant leaves and stems react similarly. Areas with lots of humidity and moisture tend to have plants that decompose very quickly, often in a slimy, gooey mess. Not a pretty sight. On the other hand, decomposition of plants in the desert takes a long time, and shows up as mostly shriveled leaves. So, keeping composure in the garden depends a lot on where you live. Do your gardens "age gracefully"?