In general, mid- to late spring is mulching season-that's when the soil is warming up from the freezing temperatures it experienced all winter. Doing it too early will slow down the warming process, which the soil needs to do its job.
What time of year should you mulch?
Why Should You Mulch the Garden in Winter? Basically, the reason you should mulch in winter keep the ground frozen by shielding it from the warmth of the sun. Mulching will keep the plant at a steady tempreture and thus dormancy. Mulching in winter will also conserve whatever water is in the soil for future growth.
Is it a good time to put down mulch?
Should you mulch plants in the fall? The short answer is: yes! Mulching around plants in autumn has all kinds of benefits, from preventing soil erosion to suppressing weeds to protecting plants from moisture loss and shifts in temperature.