In Newly Planted Beds
Clean the soil of weeds and their taproots in the planting area. It is particularly important to remove perennial weeds that have sprawling root systems before you plant Asian jasmine.
Plant young plugs of Asian jasmine in the bed, spacing them as desired to facilitate the growth of a carpet-like groundcover.
Broadcast pre-emergent herbicide granules, according to product label instructions, across the newly planted area. Wear gloves while handling the granules.
Lay a 3- to 4-inch layer of organic mulch atop the soil and granules across the planting area. Try to keep mulch from clumping on the base of the individual Asian Jasmine plants, ideally pull mulch away 2 to 3 inches from the base of each plant.
Water the planting bed thoroughly to moisten the soil for the new transplants and to activate the pre-emergent herbicide.
Monitor the planting area for the next 6 months, quickly pulling or digging out any perennial weeds that sprout. The pre-emergent herbicide only prohibits the sprouting of weed seeds, not sprouts from roots.
Refrain from using any herbicides on newly planting Asian jasmine until they are well-established, usually after 12 months. Healthy plants with good root systems will be better able to handle occasional topical herbicide sprays in the future if needed.
Replenish organic mulch as needed to maintain a layer 3 to 4-inches thick atop the soil and around the plants. Depending on climate, the mulch application may be needed once or twice per year, in spring or fall, before weeds typically germinate or sprout from dormant roots.
In Established Beds
Pull any tall weeds from the bed of established Asian jasmine groundcover. Focus on getting weeds while they are young and have not flowered and set seeds. You'll soon discover which weeds are problematic and do not pull out by hand easily.
Look at the Asian jasmine's growth. If the tips of stems are elongating and new leaves are flushing out, do not apply any herbicide sprays. Focus on hand weeding.
Mix a 1/2 to 3/4-strength dosage of a glyphosate-based herbicide, such as Roundup, into a spray bottle or backpack sprayer to be applied across the weed-infested planting bed. Follow product label directions and recommendations, but simply modify the dosage of chemical to create the 1/2 to 3/4 strength solution. For example, if full strength dosage is 1 tablespoon of product per gallon of water, reduce the amount to 2 teaspoons of product. Note that 1 tablespoon equals 3 teaspoons.
Broadcast the solution of glyphosate to the weed-infested area, focusing the spray primarily onto only the foliage of the weeds, not onto foliage of the Asian jasmine. Although the jasmine foliage has a waxy protective coating, glyphosate is non-selective, meaning it will be absorbed by all plants that are wetted with it, potentially killing them.
Monitor the glyphosate-treated area for the next 3 to 10 days, looking for weeds that are wilting or yellowing, which is a sign the herbicide is taking effect. Also note if the Asian jasmine is yellowing, a sign the dosage of chemical was strong enough to harm it.
Repeat steps 3, 4 and 5 if the initial application of glyphosate did not fully kill the weeds. Modify the strength of the herbicide solution per your evaluation of the results: if the Asian jasmine foliage was unharmed, a similar dosage or slightly stronger, up to full strength, may be used. If the jasmine greatly yellowed and was harmed by the first herbicide application, reduce the second solution's strength by 1/2.
Apply a pre-emergent herbicide, in granular form, to the bed of Asian jasmine after the weeds have been eliminated. This herbicide will prohibit the sprouting of weed seeds for several weeks or months while the jasmine plants grow and thicken in their foliage, hopefully reducing areas for weeds to sprout.