The answer to 'why is my garden mud' is that your garden likely has poor drainage, compacted soil, or excessive rainfall. Symptoms include standing water, muddy patches, and difficulty walking or working in the garden. To solve this, you may need to improve soil drainage, aerate the soil, or add organic matter to improve soil structure.
If the problem is severe or you're unsure of the cause, it's best to consult a professional landscaper. They can assess your garden and recommend the best solutions, whether that's installing drainage systems, amending the soil, or making other adjustments to improve the overall health and drainage of your garden.