Planting Ornamental Grass question

grassboroFebruary 25, 2011

I have acquired my ornamental grasses to plant this spring. I have five 1 gallon Karl Foersters, a Miscanthus Graziella and Silberfeder that are nice 1 gallon left overs from last years batch at Sooner Nursery, a 3 gallon Northwind Panicum, a 3 gallon M. Adagio and a 2 gallon Karley Rose.

I have acidic clay soil in central NC z7b. I started a 35� x 20� lasagna bed last Nov. to plant in. This went so so given that I did not do it deep enough. So now I have about 4-5 inches of partially composted organic matter on top of my original clay soil but with very few weeds (so far).

So I feel not all is wasted and I am probably better off than not doing anything. I now plan on raking this partial compost off of the original clay based soil so it can dry out some. Then dig and amend planting areas/holes, plant in mid March, spread the compost back on and mulch over this.

I would appreciate any opinions on this approach and also advice on planting the Miscanthus, Panicum and Pennisetum within the next few weeks. I believe the Karl Foersters can be planted now.

My main concern is getting the planting area/holes amended correctly to allow good drainage. I cannot do this until the clay dries some. It is quite wet now and the cover of compost is keeping it wet. Secondly, I am a bit concerned about planting the Miscanthus, etc. this soon. Two different growers have told me to go ahead and plant them now.

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You don't have to worry about planting the warm season grasses (Miscanthus, Panicum and Pennisetum) too early. They are dormant now, and won't know if they are in pots or the earth until the weather warms up. The KF will start breaking dormancy any time now, so it too can be planted now.

You're right, however, to worry about getting the soil right. You'll need to give them much better soil. I'd probably dig the wet clay out, and put it somewhere else. Then use proper soil to refill the holes. You really can't go too deep for this process, because digging holes in clay is like creating a bucket for the plants. No matter how good the backfill soil is, water will still sit in the bucket, and none of these grasses like wet feet.

Have you done a perc test on the spot where the bed will be? Dig a hole the size of a 5-gallon bucket, and pour in a 5-gallon bucket full of water. Watch how long it takes to completely drain away. If it's really slow, you need to take drastic measures to fix the problem. "Drastic measures" could include trenching the bed and installing drains to carry the excess water off. Less drastic measures could involve only digging the planting holes deep enough to get out of the clay, to a faster draining layer.

    Bookmark   February 26, 2011 at 8:08AM
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The best thing I have added to my clay soil is sand. Tons of it. The coarse concrete grade is the best but any sand is good to mix with clay. Its very cheap. We got some very large loads, but you can fill a pickup at any concrete company and its much cheaper than buying play sand at Home Depot or places like that. Your area sounds not so big so a pickup load should do it. Then all you need is a wheel barrow and just start dumping it on and mixing it in with a shovel when it dries out some. You will build up your area into a mound and that should also help drain. You can also just keep that compost on there and mix it in with the sand. The grasses love it and its easy to deeply water as the water just soaks right in quickly and weeds pull right out.

    Bookmark   February 26, 2011 at 8:03PM
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Thanks for the info about planting the warm season grasses.

As far as the half completed lasagna bed, I pulled back some today and saw Worms!! This is good. So now I feel a little better about pulling this back, amending planting holes and then puting the lasagna compost back on the ground. It should continue the positive improvements I just saw.

The NC area I live in, called the RTP area, is notorious for clay soil and land that does not perk. We live in a geological formation that has soil created from weathered sandstone and shale. The big "no no" around here is adding sand. It will make concrete here. They do say you can use washed "sharp sand".

I am going to amend my planting holes with a lot of organic material, dig extra wide holes and elevate the plantings. I do not think I will be able to raise the entire area. I will incorporate some of the lasagna bed compost. I am also researching gravel to add to the planting holes. I have read some about 1/4 -10 gravel. This is a mix of 1/4 inch and .196 inch washed gravel with no fines. The fines being the very small particles that help make concrete with the clay soil. Seems like this is being used a lot in the Pacific Northeast. The gravel folks around here have never heard of this but they have something very similar called 78 gravel. I read an article by "Wind Dancer Garden" where they indicated they use this in all of their gardens to help soil drainage, I read on another web site where they even use this to plant lawn grass.

My main problem now is getting this clay soil dry enough to work. Got all of my grasses and I am ready to plant!

One other thing, the m. Graziella and m. Silberfeder I bought from Sooner Nursey seemed to have come in good shape. Nice size plants for 1 gallon containers. I have never purchased mail order plants before. I may have got lucky in ordering early and getting leftovers from last year before they got their regular stock in for the year. These may be larger plants than their normal 1 gallon plants.

    Bookmark   February 26, 2011 at 11:06PM
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Considering that loam is composed of sand, silt and clay, (about 40-40-20% respectively), I stand by my recommendation to add sand. Lots of it. For years I tried adding compost and got nowhere until I added a lot of sand. Different proportions give rise to types of loam: silty loam, clay loam, sandy loam, silty clay loam and loam.

Loam is the desirable medium in which to grow grasses.

    Bookmark   February 28, 2011 at 2:21PM
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Catusgarden, I do appreciate your response about your experience with amending soil for growing grasses. I do know this much, I am starting to learn a whole lot more about this topic just because I am planting ornamental grasses. I am also appreciating the differences in results, locations of the country, etc. as it relates to amending soil. I have also seen "use sand" "don't use sand" on the web.

I write this as it pours outside. Nothing like having your first ornamental grasses on the deck, your planting design decided on, bags of soil amendments in the yard, spring in the air and you can�t do anything because the soil is too wet.
Got to love it!

    Bookmark   February 28, 2011 at 8:13PM
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I used to live in Fayetteville, NC and the soil there was different than here in Oklahoma, thats for sure. It was almost white on top in that area. In Oklahoma, up north in the good dirt, farming part, the soil is quite sandy. My sister could grow anything well. That was one reason I added sand, it just made sense. You might just try a little experiment in a small area with some play sand. See what happens. It beats digging drains.

I am checking out Sooner Nursery. Sounds like you got good grass plants and its nice to have a reference before ordering online.

Good Luck.... we are in a drought, by the way.

    Bookmark   February 28, 2011 at 9:12PM
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i have ordered 12 pampas grass they come in form of plugs how do i plant them why they are plugs and is there any kind of fertalizer you have to use for them

    Bookmark   March 3, 2011 at 11:42PM
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If the "5" in your name line is your zone, you are probably in too cold a zone for Pampas Grass (Cortaderia selloana). One of the hardiest cultivars, 'Pumila,' is only good to zone 6.

    Bookmark   March 4, 2011 at 7:08AM
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I'm in central Florida and I have a few small grasses in containers around my ponds but I have been wanting to start a large area of grasses in my front yard. I have a pretty large area - sort of kidney shaped - and there is a little shade from a large oak from the neighbor's yard but mostly sunny. My idea is to put tall grasses across the back and plant shorter ones as I come out towards the front. But would it be better to just mix different kinds of grasses all together or each kind of grass in little sections with a short grass all across the front? Or still yet mixing different colors or staying with similar colors. I am confused as to what looks best and also in looking locally I don't find very many grasses other than the red or white fountain grass - which seems so ordinary. If I order from an online nursery it would take a large order since I am going to need so many to fill up my space. Suggestions, please. Sorry for the long post.

    Bookmark   April 15, 2011 at 7:49PM
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I just saw your post. Mixing grasses takes some thought, you don't want to end up with a mess and its hard to visualize. Planting in groups of 3 or 5 etc (odd numbers) of the same variety to form separate mass areas is a good design principle. Don't mix too many varieties together or else it will look like a collection or display garden. Or a confusing mess.

You need enough plants to form a group of the same kind of grasses to make a definite visual statement, especially on the smaller and shorter front ones. Separate groups of all one kind that contrast nicely with the other groups will insure each mass planting makes a definite statement and compliment the entire area and making for definition and visual interest.

For example, choose all of them to be clumping type, basically upright grasses with one group of small soft light green, fine leaved grasses contrasted against something perhaps taller, more upright, stiff and blue and then a reddish tint leaved group of more vase shaped grass. (You get the idea)

A good basic rule is keep it simple. I concentrate more on the leaf color, plant form and height rather than the flowers when thinking in terms of combinations in any type of planting. However, something that will flower early and long, while staying neat would also a consideration for the small front "ground cover" ones, such as Pennisetum 'Hamlyn' or Stipa tennuissima.

Plant a drift of small neat ones, then you could have a more medium height layer along with perhaps some taller ones to set the medium ones off. Just make sure they are different enough from each make their own statement but not so different as to be jarring to the eye. Keep the spacing correct according to the mature size so you don't overcrowd the whole area.

    Bookmark   May 14, 2011 at 2:27AM
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