Although the feathery foliage and pretty puffy pink flowers of the mimosa (Albizia julibrissin) make it among the prettiest of flowering trees, it is known for dropping lots of seeds that germinate into pesky seedlings. Ridding your landscape of the seedlings can be accomplished through mechanical or chemical means. Cutting the saplings with a power lawnmower, string weed cutter or with hand pruners can diminish their growth. Don't forget trying to pull up small seedlings. Alternatively, applying herbicide on the foliage or on the cut stem of the sapling is effective, too.
Mechanical Control: Hand-Pulling
Put on gloves. Use a pair of thick cotton or leather gloves that will improve your traction on the smooth stem of the mimosa seedling.
Grasp the seedling at its base, closest to the ground where the stem is thickest and easiest to gain a solid grip.
Stoop with your legs bent and with your grasp firm around the seedling's stem base, pull upward with the strength of your leg muscles, keeping your back straight and head upright.
Pull out the roots of the seedling and toss it upon the ground or compost pile to dry and die.
Attempt alternative mechanical methods if hand-pulling the weedy seedling is too difficult or ineffective.
Mechanical Control: Cutting
Examine the scope of the seedling problem as well as the height of the seedlings and their stem diameters. Small, soft seedlings that are no taller than 12 inches can be cut down easily with a power lawn mower if growing in turfgrass or a meadow. Those 6 to 24 inches in height can also be cut down with a string or blade weed cutter, as long as the stem diameters are not greater than a quarter inch. Larger seedlings must be cut down to the ground with hand pruners or loppers.
Sheer the seedling as low to the ground as possible, completely severing the stem. Make the cut flat so that no sharp edge remains on the stem that could cause discomfort if stepped on by you or a family pet.
Place cut plants on the ground or compost pile to dry.
Repeat steps 1 through 3 as needed across the growing season to diminish the seedling problem. A combination of equipment can be used as needed, based on landscape use and access. Roots of the cut seedlings will sprout new stems, but consistent and repeated removal of them weakens the plant and eventually will kill it.
Chemical Control: Foliar Application
Purchase a broad-spectrum herbicide containing the active chemical ingredient glyphosate or triclopyr. Look at the product's front side label for the specification and percentage of the active ingredient.
Mix the herbicide per the product directions and place in a spray bottle or backpack sprayer.
Spray the foliage of the mimosa seedlings thoroughly, getting the herbicide solution on all green stems, leaflets and even flowers if present. Coat the seedling until herbicide solution lightly drips off the plant.
Monitor the seedling over the next two to seven days, noting if the herbicide application was effective. Look for leaf yellowing and eventual shriveling of foliage and stems.
Chemical Control: Stump Application after Cutting
Prepare a mixture of herbicide as outlined in Section 3, Chemical Control, Steps 1 through 2. Place the herbicide in a spray bottle and have it near the site of the seedling to be eradicated.
Follow and carry-out guidelines for Section 2.
Spray herbicide solution on the cut wound of the stem stump that remains after it is cut back with the pruners or loppers. Do this when the wound is fresh and wet, so the herbicide is quickly absorbed by the vascular tissue in the stem and pulled into the root system.
Monitor the stem stump for the next one to three weeks, watching for signs of life. If the herbicide was effective, no new growth should sprout because the chemical infiltrated and effectively killed the root system.
Repeat Section 2, 3 or 4 per your preference if the mimosa seedling sprouts back and an additional eradication treatment is necessary.