Miscanthus Giganteus is adaptable to many types of soils, but will perform it’s best in fertile types that hold moisture, but are well draining too. Swampy areas that hold moisture most of the year will not work well for this plant. It has a woody root system and can rot with too much moisture. We have grown it in areas that have standing water in spring for a few weeks, but drains later on and it does well. If you are concerned about too much moisture you may make little berms of sandier soil that will drain well in wet areas.
Your site should receive 6 hours of sunlight for good height. Any less than 6 hours of full sun may produce shorter plants. Miscanthus Giganteus will not grow well in full shade and may even die out.
If you have very infertile or sandy soils you will likely want to amend areas where you are planting this. After a year or two of establishment it should adjust to your normal conditions, but amending right where you are planting will help it the first year when plants are more vulnerable to any adversities. Amend sandy soils with compost, peat, manure, or a combination of any of these. Add within the planting holes and you may top dress as a mulch with this too.
When planting in soils that are moisture saturated, especially while it’s cool out, roots must have superior drainage. Roots will not have adequate feeder root to take up excess moisture and will not grow the feeder root until air temps warm to around the mid 60’s. Eliminate rot and mold issues by adding sand for a few inches around the roots, a good shovel full or two of sand per hole can greatly help.
The only losses of plants both to us and to customers that we have seen have come from too much or too little moisture when planting. You as the purchaser are responsible to amend your planting area as needed to ensure the best chance for success.
It is best to plant as soil temperature are near 50 degrees or above is even better. This allows the feeder root to begin development and helps the plant begin to establish. Fall planting has worked well for us as soil temperatures are still quite warm, even when air temps are cooler. Soils are not usually as saturated with moisture in fall as they can be in spring with snow melt and spring rains.
Once the ground freezes it will not accept more moisture and the roots are protected from rot issues through winter so long as there are not a lot of freeze and thaw cycles through winter. Fall plantings have a head start over spring planted roots and are capable of withstanding the extra moisture of spring much of the country will have, due to the time it has had to developed the feeder roots. Fall planting should happen as soon as possible after receiving the plants.
We recommend fall planting only for zones 5b and warmer. Since we are not able to harvest roots until late Oct. (after we have had a few good frosts), it makes very late planting for colder climates and there is little time for feeder root development in fall in zone 4-5a. Those in colder climates are best to wait for spring planting, normally in late April through May.
When planting in spring, try to time the planting to when conditions are still good and wet out, unless you have supplemental watering available. While it is the very best to wait until air temps are in the mid 60’s, and soil temps at least in the 50‘s, conditions may start becoming dry at that point, and you will be better off to plant while it is a bit cooler than 60 degrees, but still wet out. Soil should not be sloppy wet, if you can dig a hole and water stands in it, it is too wet out –but this shows you may have several weeks left before the soil to becomes dry, giving you time to plant.
Eliminating competing vegetation is a necessity for miscanthus giganteus to establish well. If you are able to spray the area with an herbicide before planting, this is best. If you are opposed to using chemicals you can scrape off the top layer of vegetation and that can help.
Actual planting is often done by hand, though some people will use a seedling tree planter for single rhizomes. We suggest you plant single rhizomes 8”-1’ apart. 1/2 gal. divisions are usually spaced 1.5’-2’ apart and 1 gal. plants 2.5’-3’ apart. Dig a hole large enough to completely cover the root size you are planting. This may take one or two shovels full of soil removed. Roots should be completely covered with 2-4” of soil on top.
Many people will plant more than one row and stagger the planting in a zig zag fashion for more visual coverage sooner. Plant extra rows spaced about the same recommendation, (1’-2’ or 3’ apart depending on root size).
When placing the root in the planting hole, you may face the root system any which way, (single rhizomes may by laid out flat, crosswise). The roots have many growth buds on them and they will find their way to the surface. If you can see the rhizomes have shoots that will grow stems it can be helpful to point them upwards, but it is not imperative that you do so. It just gives them the head start on finding their way up.
Amend soils are you plant as discussed previously and tamp the soil down after covering the root with 2-4” of soil. This helps keep the roots away from the drier soil surface and will pack the soil to remove air pockets.
You may mulch around the areas where you plant, which will mark your planting spots as well as act to suppress weeds from regrowing and help keep moisture in the ground. Compost, manure, wood chips and straw are all good choices for mulch.
MORE WEED CONTROLS
As spring weed competition greens up, you can spray an herbicide around the the planting area if room allows (2-3’ spacing). Herbicides will kill the miscanthus so you must to careful if this grass is actively growing. Pre-emergent products (such as Simazine) can keep vegetation from growing from new seeds. This should be applied right after first planting, or each spring if needed before the miscanthus is growing, following direction on the package. Products like 2-4D will kill off broadleaf weeds but not damage miscanthus and can be used during the growing season.
Another method used for weed control is to place a thin, inexpensive grade of landscape fabric around the plants. You can do this by laying the fabric out, pinning it down with pieces of wire bent to make small stakes, and then cutting holes in the fabric when you plant. Or you can place the fabric around areas you have already planted, being sure not to cover the plants themselves. This method helps keep weedy plants from growing while the miscanthus establishes and also acts a mulch, keeping moisture in. The grass is vigorous enough that it will grow right through the ground cover in years to come as it spreads, and a cheap grade of landscape fabric should break down in a few years time. So for a small investment you will have helped your plants greatly, eliminated the need for sprays and herbicides to a great degree, and it also marked the areas where your grass is planted.
Be aware that newly planted roots most often will not sprout through the soil in the same time frame. You may see results in a staggered time frame. It is just the nature of this grass, patience is a virtue this first year, and in years to come you will see it push forth growth at a more consistent rate overall.
Miscanthus Giganteus is a warm season grass and will not have top growth until temperatures are in the mid 60’s regularly, which is usually mid May in Michigan. First year plantings can take longer to emerge than established patches.
This grass benefits from fertilizer in the first year. We use an all purpose type. Miracle Grow or 12-12-12 and similar types will work well. Miscanthus giganteus has no great needs for fertilization after the first years as it stores the nutrients from the leaves each fall within the root system. It cannot hurt to fertilize though, just be aware that you are fertilizing area weeds too!
This grass will regrow through old debris each spring. You do not have to clean an area up, though it will look better to have the grass cut back and debris from fallen leaves cleaned up when using this around your home. In a more natural setting you may never need to clean up the debris. If you choose to do so you may burn the debris, or mow or chop back the stems if you wish.
DIVIDING YOUR GRASS
It is best to divide every few years if you are wanting divisions off your own plants. You may divide even after one year as the root system will roughly triple in size in one year.
The root system becomes very compacted in short time and most often you will need to dig the entire clump to make divisions. You will not be able to shovel out a portion of the root system after just two years or so. It can take power equipment to remove large clumps 2-3’ around or more and they become very heavy with soil on. Best to divide while they are 1-2’ across. Simply chop your clump in half or in smaller chunks with a spade or ax. A electric saw all works well on this. Try to make your divisions no smaller than 6-8” single rhizomes. Remember, individual rhizomes pieces will grow with the right conditions, but it is always best to start with larger divisions for best success. Replant as per directions.
ENJOY! and thanks for your interest in Miscanthus Giganteus.