Bulbs
Flower Basics
Flower Beds & Specialty Gardens
Flower Garden
Garden Furniture
Garden Gnomes
Garden Seeds
Garden Sheds
Garden Statues
Garden Tools & Supplies
Gardening Basics
Green & Organic
Groundcovers & Vines
Growing Annuals
Growing Basil
Growing Beans
Growing Berries
Growing Blueberries
Growing Cactus
Growing Corn
Growing Cotton
Growing Edibles
Growing Flowers
Growing Garlic
Growing Grapes
Growing Grass
Growing Herbs
Growing Jasmine
Growing Mint
Growing Mushrooms
Orchids
Growing Peanuts
Growing Perennials
Growing Plants
Growing Rosemary
Growing Roses
Growing Strawberries
Growing Sunflowers
Growing Thyme
Growing Tomatoes
Growing Tulips
Growing Vegetables
Herb Basics
Herb Garden
Indoor Growing
Landscaping Basics
Landscaping Patios
Landscaping Plants
Landscaping Shrubs
Landscaping Trees
Landscaping Walks & Pathways
Lawn Basics
Lawn Maintenance
Lawn Mowers
Lawn Ornaments
Lawn Planting
Lawn Tools
Outdoor Growing
Overall Landscape Planning
Pests, Weeds & Problems
Plant Basics
Rock Garden
Rose Garden
Shrubs
Soil
Specialty Gardens
Trees
Vegetable Garden
Yard Maintenance
How to Kill Agapanthus
Control agapanthus by digging up the bulbs, covering the plants with black plastic, or spraying with a glyphosate herbicide.
Agapanthus (Agapanthus spp.) are fuss-free bulbs that feature rounded clusters of trumpet-shaped blue, purple or white flowers, but their vigor means they return every year and spread, even if you don't want them to. Growing in U.S. Department of Agriculture plant hardiness zones 6 through 10, agapanthus, also called lily of the Nile, grow in clumps 1 1/2 to 4 feet tall and 1 to 2 1/2 feet wide. You can dig the plants up to control agapanthus, or you can spray the plants with weedkiller.
Digging Up Bulbs
Agapanthus bulbs sprout new shoots every year, but you can control the plants by digging up the bulbs. The best time for digging up agapanthus bulbs is in fall or winter when the plants have stopped growing.
Step 1
Push a garden fork into the soil at one edge of the problem agapanthus patch.
Step 2
Lever the fork upward to lift the agapanthus bulbs out of the soil.
Step 3
Dig up the bulbs in the same way all over the patch.
Warning
Don't leave any small agapanthus bulbs or pieces of bulb in the soil. Any agapanthus bulbs left in the soil may grow into new plants.
Spreading Mulches
Mulches control agapanthus by blocking the light from the plants. A sheet of black plastic works best because it also reduces the water that reaches the plants and agapanthus shoots can't grow through it. Agapanthus is so strong growing it can penetrate loose mulches such as compost or shredded bark.
Things You'll Need
Pruning shears
Rubbing alcohol
Black plastic sheets
Rocks
Step 1
Prune the agapanthus stems at soil level with pruning shears.
Step 2
Wipe the pruning shear blades with a cloth that was soaked in rubbing alcohol, which helps prevent pests and diseases from spreading.
Step 3
Spread a sheet of black plastic over the agapanthus plants.
Step 4
Place rocks on the edges of the black plastic sheet to weight it down.
Step 5
Leave the black plastic in place for one growing season. Pull out any agapanthus shoots that appear at the edges.
Spraying Weedkillers
Systemic herbicides, such as glyphosate, control agapanthus by moving through the plant to its bulbs. A ready-to-use 2 percent glyphosate herbicide controls agapanthus effectively.
Things You'll Need
Ready-to-use glyphosate weedkiller
Long-sleeved shirt, long pants, socks, sturdy shoes
Chemical-proof gloves and safety goggles
Warning
Glyphosate kills most plants it touches. Don't spray glyphosate near plants you wish to keep, or protect the plants with cardboard or other coverings before spraying. Remove the coverings when the glyphosate is dry. Use the herbicide on a calm day to minimize spray drift.
Step 1
Put on long pants, a long-sleeved shirt, safety goggles and gloves. Choose a dry, still, dull day.
Step 2
Spray all agapanthus parts with the glyphosate herbicide.
Step 3
Spray any new shoots that appear later in the growing season when they are 6 inches long.
Tip
For the most effective, long-term control, spray agapanthus with glyphosate in spring when the plants are growing new shoots.
