Plant Mondo Grass – Spring or Early Fall

Plant mondo grass in spring or early fall: set the crown at pot depth, space for the fill you can wait for, and water until the clumps knit.

Plant in spring or early fall, with the crown at pot depth

Set every plant out on the bed before you dig, then stagger the second row. Work compost into the top soil so new roots find moisture under trees. [1] [2]

How to plant mondo grass

Work one row at a time: confirm Ophiopogon, set the crown, space for the clock you want, then water to settle.

1. Read the Latin. Skip a tag that only says monkey grass or lilyturf unless it also says Ophiopogon.
2. Clear weeds. Mix compost into the top soil. Do not till under established trees if you would cut feeder roots.
3. Knock the plant from its pot and loosen circling roots. Set the crown at the same depth it grew in the pot — the top of the ball at or slightly above grade.
4. Space standard green mondo about 6 to 12 inches apart. Plant O. japonicus ‘Nana’ tighter, about 4 to 6 inches, for edges and stepping-stone gaps. Set O. planiscapus ‘Nigrescens’ about 4 inches apart if you want a dark ribbon sooner.
5. Backfill, firm gently, and soak the bed. Mulch lightly between plants and keep mulch off the crowns.
6. Water through the first growing season whenever the top few inches dry. After the clumps knit, water only in long drought.

How to divide mondo grass

Division is the usual increase. Lift an established clump in early spring or early fall — the same windows as plant-out.

1. Soak the clump the day before so the roots slide apart without tearing dry.
2. Dig under the clump and lift it. Tease fans apart by hand, or cut with a clean knife.
3. Keep roots on every piece, and several leaves. Tiny leafless scraps reset the slow clock. [3]
4. Replant at the same depth, at the same spacing as new plugs, and water until new growth takes.

What fails at planting

Sparse hot-dry plugs stall. Soil over the crown rots new growth. A mix that stays soggy in a pot does the same. [4] Black mondo is a slow accent — it will not smother a bed the way a weed would.

In a pot

O. japonicus and dwarf kinds make a soil cover in a mixed container. Use a pot with drainage holes and a quality potting mix. Set the crown ½ to 1 inch below the rim, water until it drains, and check moisture more often than in the ground. Do not leave the pot sitting in a saucer of water.

Set crowns at pot depth, space for the fill you can wait for, water the first season, and divide only pieces that still have roots.