Weedier is the comparative form of weedy.
A garden more overgrown with unwanted plants is weedier than one that's been tended.
Of people, weedier describes someone thinner and more gangly than another: He was even weedier than his brother, all elbows and knees.
1. botanical — overgrown, Excessively covered in vegetation; unkempt (Untidy in appearance); scraggly (Irregularly sparse and messy); tangled (Twisted confusedly together); wild · untended · invasive · sprawling · choked · neglected · rank · uncultivated · straggly · leggy
2. physique — scrawny, Unattractively thin and bony; gangly (Awkwardly tall and thin); lanky (Tall and ungainly thin); skinny (Very thin, underweight); thin · spindly · bony · gaunt · slight · lean · underweight · stringy · reedy · willowy
Opposites
vegetation/garden maintenanceweedier ≠ neater More orderly; trimmer · tidier · cleaner
physical build (informal)weedier ≠ stockier More solidly built; burlier · sturdier · heftier · bulkier · beefier