How do you weed a myrtle ground cover?
From personal experience with a 300 sf area: Before planting, spray the area with grass and weed killer, hopefully one that is environmentally friendly. Then plant the myrtle and mulch between the plants. The few weeds that subsequently come through are picked by hand , when the weeds are young before they become established. Keep at it until the myrtle fills in, after which there should be even fewer weeds coming through, which can be picked by hand.