The Japanese blood grass reaches a height of 30 cm to 40 cm and develops conspicuous reddish leaves. In the course of summer, the intense red color increases, which in mild locations lasts into winter. In the open field, the silver hair grass forms long runners and over time covers larger areas. In contrast, the Japanese bloodgrass is a little more cautious. Garden enthusiasts who use this ornamental grass to set decorative accents at certain points therefore prefer to cultivate it in a planter.
Table of Contents
The red-colored ornamental grass, which comes from Japan, needs a protected location that meets the requirements in order to develop the desired blaze of colors:
- Sunny to partially shaded, warm location.
- Humous and well-drained soil quality.
- The Imperata cylindrica goes into clayey, heavy earth.
- The wild form of the silver hair grass also thrives in poor, sandy soil.
With a stature height of 30 cm to 50 cm, the Japanese bloodgrass not only comes into its own as a single plant, but also enriches mixed herbaceous borders and is suitable as a decorative planting on the edge of woody plants. The Imperata cylindrica should only be considered as a border planting of the garden pond if waterlogging cannot develop there. The larger silver hair grass with its picturesque habitus, on the other hand, is often used when it comes to planting areas and slopes at risk of erosion. It is less common in the home garden because it is considered an invasive plant.
Until the Japanese bloodgrass has acclimatized in its location, it needs a little attention from the hobby gardener, which is reduced to a minimum in the following years:
- Water regularly in the first year of standing.
- In later years only water in dry periods.
- Regular mulching keeps the soil moist and warm.
- Avoid the formation of waterlogging.
- Work some compost into the soil every few weeks.
- Alternatively, give a dose of complete fertilizer every 4 weeks.
- In winter only water a little on frost-free days and do not fertilize.
- Cover with leaves, straw or brushwood in harsh locations in winter.
- Cover it as a container plant with a jute sack or bubble wrap.
- In addition, place it on a wooden board or a styrofoam block.
- Remove winter protection in good time in spring.
If the Japanese bloodgrass is cultivated in a planter, there is a risk that the root ball will freeze completely, even with adult plants in winter. Even the strongest growth does not recover from this. A protective cover in connection with a safe location on the south wall of the house is therefore essential.
Ornamental grasses such as Imperata cylindrica are only cut in spring, and there are several reasons for this:
- The stalks protect the root area from snow and ice.
- Even when dry, they adorn the garden, covered with hoar frost.
- The dense clumps provide shelter for small animals in the garden.
If the blood-red stalks are already stretching high into the sky, they are loosely tied together in autumn. The silver hair grass, which grows up to three times higher, is in any case wrapped in tufts with cords. On the one hand, this measure increases the protective effect for the root area and makes cutting easier in spring. The best time to cut is the phase before the new shoot. Depending on how mild the winter was, this can be quite early in the year. Under no circumstances should it be freezing or the intense winter sun shouldn’t be high in the sky. A sharp cutting tool, sturdy gloves and eye protection are essential for this work, because the ornamental grass is not called sword grass for nothing. The edges of the stalks are covered with silicate crystals, which makes them so sharp, that they can cause deep cuts in unprotected skin; not to mention the damage the tips of grass can do to an eye that isn’t shielded by glasses.
The silver hair grass and its cultivated form, the Japanese blood grass, are ideally cut to a hand’s breadth above the ground. Before that, the experienced hobby gardener examines the clumps for small animals that may still be hibernating. Out of consideration for the dormant beneficial insects, the work is postponed for a few more days. In addition, he will determine whether the new shoot is already showing. If this is the case, the grass is cut to just above the young stalks. If their tips are cut, they turn brown and the decorative habit is gone for the time being. If the winter was unusually mild, even experienced gardening enthusiasts may be surprised by the particularly early budding, which is already well advanced at the first inspection. A conventional cutting measure is then refrained from. Only the dead plant material in the eyrie is removed as far as possible so that light and air can get to the young grasses. To encourage lush growth, a well-measured dose of compost is worked into the soil after cutting.
As part of the annual pruning, there is the perfect opportunity to multiply the Japanese blood grass or silver hair grass. Since these types of grass form underground rhizomes, they can be multiplied by division
- Use the spade to expose part of the root area.
- Separate a 10 cm to 15 cm long rhizome neatly.
- The section should have at least one shoot bud.
- The interface is treated with wood ash powder.
- Plant this piece of root in a suitable location in the garden.
If the specimen is still young, the entire root ball is dug up and divided.
In late summer there is the possibility of simply propagating the ornamental grass with cracks. In principle, this is a combination of head cutting and stick division. For this purpose, part of the root system is exposed and a strong stalk and roots are pulled out. The advantage over a cutting is obvious: the crack already has its own roots. So that the root system can develop further, the stalk is placed in a glass of water, preferably willow water, for a few days. It is then grown throughout the winter in a pot with low-nutrient potting soil in a frost-proof place until it finds its final home as young silver hair grass in the spring bed or as Japanese blood grass in the bucket.
Repot in good time
In view of the decorative habitus of Imperata cylindrica, the red cultivated form of this sweet grass is predestined for cultivation in the tub on the balcony, terrace or in the front garden. Since the roots reach up to 120 cm deep, the knowledgeable gardener chooses appropriately shaped planters in which the roots are not so quickly narrowed. Depending on the vigor of the cultivated specimen, it is time to repot the Japanese bloodgrass at the latest when the roots push their way up through the surface.
- The new bucket is only slightly larger than the previous one.
- If there is no water drainage hole, it must be drilled.
- Lay a drainage made of coarse gravel or potsherds over it.
- Cover the drainage with air and water permeable garden fleece.
- Mix of garden soil, compost and sand suitable as a substrate.
- Pot the ornamental grass and examine it.
- Cut off diseased, rotten parts of the root with a sharp knife.
- Brush the interfaces with wood ash powder and allow to dry.
- Pot in the new bucket and water well.
Experienced gardening enthusiasts leave a watering edge free, because it is really annoying if the surrounding soil is soiled with spilled, wet substrate after each watering.
Plant Japanese blood grass in a bed with a root barrier
Since a large spread of the ornamental grasses is rarely desired in private areas, the use of a root barrier is advisable when planting in beds, on the edge of the wood or on the garden pond. Silver hair grass already has a reputation as an invasive plant. In the meantime it has been reported from regions of the world with mild winter that its cultivated form, the Japanese blood grass, emulates this hustle and bustle. Despite the small growth form, it secretly forms underground rhizomes of astonishing proportions, which over time conquer an ever larger territory in the garden. The informed garden enthusiast uses this knowledge by keeping not only the silver hair grass, but also the Japanese blood grass in check by means of root barriers. The rhizome barrier consists of tear-resistant, rot-proof polyethylene,
- Determine the area within which the ornamental grass is allowed to spread.
- Draw a 60 cm deep trench at the borders.
- Pull the foil into this trench so that 3 to 5 cm still protrude.
- The protruding edge prevents the roots from climbing over it.
- The ends of the root barrier film are closed with an aluminum rail.
- Good aluminum rails have at least 4 screws.
- Serrated rails reliably prevent the film from slipping out.
- Fill in the trench again and lightly trample the earth.
The ornamental grasses are only planted within the area when the root barrier is completely in place. Plant holes are dug that are about twice as large as the root ball. Enriching the excavation with compost supports successful growth. Before the young ornamental grass plant is planted, the experienced hobby gardener immerses it in water for a few minutes so that the roots can soak themselves up. Only then does the plant get into the ground, the bottom of which was previously loosened with the rake. The heaped potting soil is then lightly trampled on and poured on well. Since young silver hair grass and Japanese blood grass still need plenty of moisture, a pouring rim that slopes down towards the middle promotes optimal utilization of the irrigation water.
Can the root block also be created later?
Garden lovers who have not yet had any experience in the cultivation of silver hair grass and Japanese blood grass, when buying the plants in containers, seldom suspect what urge to spread they may show. If in the course of time their conquest through the garden becomes recognizable, it is not absolutely necessary to dig them all up and thus to dispose of them. Subsequent application of the root barrier is quite possible, even if it involves a little more effort:
- Dig up all the rhizomes in the unwanted part of the garden.
- It is usually not enough to just cut off the runners with a spade.
- Create a ditch about 1 m from the edge of the remaining ornamental grass area.
- Apply the root barrier as described and close it with the splint.
Only with a lot of luck will all of the foothills be discovered and excavated. If new shoots appear outside the rhizome barrier in the next few months, they are immediately dug up completely and disposed of in the organic waste bin or the nearest recycling center. They would only gain a foothold again on the compost heap and spread out into the garden from there.
They are quite fractal, the advantages that the silver hair grass and the cultivated form of Japanese blood grass have to offer gardening enthusiasts. Larger areas and slopes at risk of erosion receive decorative planting with the deep-rooted silver hair grass, whose silvery shimmering ears sway gently in the wind. The significantly smaller Japanese blood grass, on the other hand, sets striking accents in every garden with its deep red stalks until winter. They are both easy to care for, apart from their insatiable urge to spread quietly and secretly. This urge to conquer, however, can be effectively curbed right from the start with the help of root barriers. Garden lovers who prefer to cultivate Imperata cylindrica in a tub,