cold season/warm season & seed 101

chapelhillgardener(7a NC OrangeCo)March 14, 2006

i know from reading this forum for awhile that there's some great grass knowledge here. i keep seeing references to cold & warm season grasses. what does that mean? does it dictate sowing times at all? this is my first year starting grasses from seed - any wisdoms on that topic would be most appreciated as well.

marsha :)

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Cold season grasses will stay green through the winter or will start growing very early in the spring. Some examples are Blue fescue and Blue oatgrass. Some of these grasses don't tolerate heat well and may go semi-dormant in summer. You can start seedlings for these now or wait, but I wouldn't start in heat of summer. Blue fescue is very easy to grow from seed and now is a good time to plant it.

Warm season grasses are generally much later to start growing and thrive during the heat of summer. This includes most of the ornamental grasses -- egm Miscanthus, Pennisetum, River oats, and many other varieties. I wouldn't start seeds for warm season grasses right now unless you grow them inside or in a greenhouse, coldframe, etc.

    Bookmark   March 14, 2006 at 8:03PM
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Marsha, here's a summary of my wintersown grass from seed last year:

2005, winterwsown ornamental grasses:

Roughly, the code is as follows:

Cells sprouted/cells sown, # seeds per cell, Name, (source (SG=self-gathered)) - how sown,

S= surface, LC= lightly covered

Flat #14
8/8 cells, 3 Festuca glauca (Park's) - S
8/8 cells, 13 Festuca glauca (Park's) - S
1/1 cell, 30 Festuca glauca (Park's) - S
15/15 cells, 14-15 Festuca glauca (trade) - S
8/8 cells, 9 Festuca scoparia (Jelitto) - S
8/8 cells, 9 Festuca mairei (Jelitto) - S
8/8 cells, 9 Festuca gigantea (Jelitto) - S
0/8 cells, 9 Pennisetum 'Burgundy Giant'(trade) - S

Flat #15
0/8 cells, 20-25 Calamagrostis x acutiflora 'Karl Foerster's Feather Reed Grass'(trade) - S
0/8 cells, 6 "Bamboo 7-9'" individual seeds(trade) - S
0/8 cells, 3 'pods' of 2-3 seeds, "Bamboo 7-9' "(trade) - S
0/8 cells, 5 "Tall ornamental grass, 8-10' large reeds"(trade) - S
8/8 cells, 10 "Foxtail type grass"(trade) - S * was Setaria faberi
0/8 cells, 15-20 "Grass, tall & feathery"(trade) - S
8/8 cells, 5 "Grass, tall, reddish top"(trade) - S * was Tridens flavus
0/8 cells, 5 Pennisetum setaceum 'Rubrum'(trade) - S

Flat #16
0/16 cells, 9-10 Anthoxanthum odoratum, (SG04) - S
15/16 cells, 8 Anthoxanthum odoratum, (Jelitto) - S
4/4 cells, 5 "Quaking Grass" (trade, larger than seeds, may be B.maxima) - S
10/12 cells, 15 Briza media (Jelitto) - S
8/8 cells, 8 Briza maxima (trade) - S
0/8 cells, Cyperus alternifolius (trade)seeds & chaff, sowed heavily and mixed in a bit

Flat #5 cont.
4/Added 8 cells, Carex grayi (trade) for 2-4 warmstrat - LC

Flat #17
16/16 cells, Carex unknown, small fine volunteers, heavily sowed (SG04)- S
14/16 cells, 9 Carex muskingumensis (Jelitto) - S
14/16 cells, 5 Chasmanthium latifolium (Trade and SG04) - S
8/16 cells, 5 Chasmanthium latifolium (Jelitto) - S

Flat #18
16/16 cells, Cortaderia selloana (trade)heavily sowed, w/chaff - S
0/16 cells, 9 Erianthus ravennae (trade)w/chaff - S
0/8 cells, ~15 Helictotrichon sempervirens (trade)w/chaff - S
5/8 cells, 9 Hystrix patula (Jelitto) - S
5/16 cells, 8 Lagurus ovatus (trade) hulled - S

Flat #19
0/8 cells, 6 Leymus (trade)hulled - LC
0/24 cells, 5-6 Liriope minor (trade) - LC
11/32 cells, 8 Luzula nivea (Jelitto) - S

Flat #20
13/24 cells, 5-6 Luzula sylvatica 'Select' (Jelitto) - S
0/8 cells, 5 Miscanthus sinensis condensatus 'Cosmopolitan' (trade source 1) - S
0/8 cells, 8 Miscanthus sinensis condensatus 'Cosmopolitan' (trade source 2) - S
0/8 cells, 8 "Variegated Japanese Grass" (trade) - S
0/8 cells, 8 Miscanthus sinensis 'Gracillimus' (trade) - S
0/8 cells, 8 Miscanthus "Unknownus" (trade) - S

Flat #21
0/8 cells, 10 Miscanthus sinensis 'Zebrinus' (trade source 1) - S
0/8 cells, 10 Miscanthus sinensis 'Zebrinus' (trade source 2) - S
1/8 cells, 9 Miscanthus sinensis 'Central Park' (trade) - S
0/8 cells, 9 Miscanthus sinensis 'New Hybrids' (SG04 1st bloomers) - S
0/8 cells, 9 Miscanthus sinensis 'New Hybrids' (SG04 2nd bloomers) - S
6/8 cells, 9 Miscanthus sinensis 'New Hybrids' (SG04 full mix) - S
2/16 cells, 6 Millium effusum 'Aureum' (Jelitto) - S

Flat #22
31/32 cells, 12 Muhlenbergia capillaris (trade) - S * was Eragrostis spectabilis
0/16 cells, 3 Pennisetum glaucum 'Purple Majesty' (trade)hulled - S
0/16 cells, 5 Pennisetum glaucum 'Purple Majesty' (trade)hulled - S

Flat #23
24/24 cells, 9 Pennisetum alopecuroides (SG04)hulled - S
12/24 cells, 9 Pennisetum alopecuroides 'Moudry'(trade)hulled - S
0/8 cells, 6-7 Pennisetum ? "Dwarf Fountain Grass" (trade)hulled - S
0/8 cells, 5 Pennisetum glaucum 'Purple Majesty' (trade)hulled - S

Flat #24
16/16 cells, 9 Sesleria caerulea (Jellito) - S
0/16 cells, 9 Sesleria nitida (Jellito) - S
7/8 cells, 9 Stipa capillata (Jelitto) - S
3/16 cells, 9 Nassella tenuissima (AKA Stipa tenuissima) (Jellito) - S
0/8 cells, 5 Tripsacum dactyloides (trade)hulled - LC


704 cells sown with several thousand seeds, 51 varieties.
308 cells sprouted, 43.7%


Cultivar grasses like named Miscanthus and Feather Reed, did not, for the most part, sprout. Neither did 'Purple' Pennisetums, and a few of the unknown 'Bamboo' described

Cold season grasses seemed to sprout at a higher percentage than warm season grasses. I'll confirm this next year, and spring-sow warm season grasses, after wintersowing cool season grasses.

Some Jelitto sourced seeds did well, others did poorly. Where I still have some left, I'll spring sow them next year. I ran out of flats last winter, and did no spring sowing.

M.s. 'New Hybrids' have two distinctly different bloom times, but the seeds gathered from each blooming did not sprout at all. They may not have been ripe. The last batch gathered was a mix of both, and were left on the plants much longer. They sprouted, but not as well as spring-sown seeds 2 years ago, and direct-sown seeds this year.

Clumping grasses: Festuca glauca cells were sown with from 3 to 30 seeds each. Today, you can't tell the difference between the clumps.

Briza maxima, an annual grass, self-seeded vigorously before I harvested the seeds.

Setaria faberi, Giant Foxtail, an annual, is extremely vigorous. It reached 5+' from seed, and seedheads were higher. To prevent reseeding, I cut it to the ground in early September, before seeds were ripe. It grew back to 1.5' and threw up new seedheads.

Eragrostis spectabilis, traded to me as Pink Muhly, is a fantastic grass. It's got a gorgeous pinkish-purple cloud-like infloresence that lasts for 2 months, so far, and is very fine. The flowers catch moisture droplets out of humid air or rain, and glisten nicely. It also germinates beautifully (96.8%). Highly recommended as a massing grass or low border.

Pennisetum glaucum 'Purple Majesty' was a real disappointment, but I'm going to do them again. I got no sprouts from 40 cells, 3-5 seeds each. Next year I'm going to try them again, in a variety of ways, from WS to spring-sowing to direct-sowing.

    Bookmark   March 15, 2006 at 6:17AM
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chapelhillgardener(7a NC OrangeCo)

dawgie - thanks so much for the warm/cold season made simple for this novice. i've got festuca glauca "azure blue" sprouting in the cold frame, along with briza maxima. i see from donn's coding that i shouldn't have covered them with soil, but in my ignorance i did - and they sprouted in spite of me :)

donn - what awesome record-keeping. i'm a garden record-keeper, too. there's MUCH to absorb from your data and i really appreciate your posting it. the 43% germination rate is striking - looks like i'll *have* to buy any miscanthus or pennisetum i want. the the p. purple majesty got quite the bashing in the professional gardener forum awhile back for it's failure to perform in all aspects. maybe i'm not so disappointed that i can not find the seeds i made a trade for :) but, your muhly data is encouraging!

my cold frame appears to be a must for ornamental grass starting.

thanks so much, both of you :)

    Bookmark   March 15, 2006 at 11:33AM
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grolikecrazy(6-7 UT)

hi Donn, I believe that the reason why yiou didn't get much out of your Miscanthus is because their seeds are in fertile hybrids and so must be propagated only by division.(Thought you might want to save your time and not try again to sprout these. Here's an excellent website on it. (Am not sure why the link doesn't go live when pasted in here):

if you can't get it , here's an excerpt of it:

Why Arent All Grasses Grown From Seed?

Many of the grasses sold on the market today cannot be propagated from seed. Some of these grasses are sterile hybrids, which means that the seed is not viable. Calamagrostis ÂKarl Foerster is an example.

However, more often it is a case of a specific ornamental grass maintaining its characteristics only by being vegetatively propagated. Many of the more decorative grasses have a special trait such as a strong red leaf colour (eg. Panicum virgatum ÂShenandoahÂ) or a larger size or a more beautiful flower. A grower noted this and decided that such a trait was worth preserving. So it was done by vegetative propagation  by separating or dividing the parent plant into many smaller plants, over and over again. Seeds from Panicum ÂShenandoah will not produce plants that look like it, rather it is likely to produce plants that look like Panicum virgatum, a much greener plant. The only way to obtain more Panicum ÂShenandoah plants is to divide it.

It is very easy to tell at a glance which grasses are vegetatively propagated. Its in the name. Simply look for a name in single quotes, for example, Panicum virgatum ÂShenandoah or Festuca glauca ÂElijah BlueÂ. Panicum virgatum is the species name and ÂShenandoah was the name given to that particular plant. Vegetatively propagated grasses will always have a uniform look in the landscape, that is to say that they will all be approximately the same size, shape, height and colour.

You may have noticed how many cultivars of Miscanthus sinensis exist. That is because its seed produces highly variable plants. Growers have noticed this and selected a number of beautiful plants. The variation is amazing! Hence there are over one hundred distinctly different Miscanthus sinensis cultivars available on the market today.

Grasses without the single quote in the name are often grown from seed. These seed grown grasses will vary slightly in colour and size. For example Festuca glauca will vary from blue to blue-green. Some may be bushier, others more upright, etc. Seed grown plants are often less expensive to produce, hence they are priced lower than the more labour-intensive divided plants.

So if you are doing a mass-planting of a single grass, give some thought to how important a uniform look is to you. If you are considering the less expensive seed-grown plants, feel free to ask us about the plant's uniformity, as some grasses show little variation from one plant to another.

Every once and awhile plants are mislabeled. With the huge number of plants on the market this is unavoidable. Pennisetum alopecuroides 'Hameln' appears to have been a victim of this, as some plants labeled as P. ÂHameln are proving to be much larger for some people than for others. It should be that all P. 'Hameln' are the same size. We take very seriously the maintaining of the correct name. In the case of P. 'Hameln' we do in fact have the dwarf variety.

    Bookmark   December 16, 2008 at 1:08AM
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Hi grolikecrazy,

"hi Donn, I believe that the reason why yiou didn't get much out of your Miscanthus is because their seeds are in fertile hybrids and so must be propagated only by division.(Thought you might want to save your time and not try again to sprout these."

This is a pretty old thread. Since my post here, I've successfully grown M.s.'New Hybrids' (as well as 'Early Hybrids' and 'Late Hybrids') and M.s. 'Gracillimus' from seed. I've also had them all self-sow in my warm zone 7 garden.

The key, in each case, has been to start the seeds later than winter sowing. Mid-Spring is plenty early enough to put them out, and give the seedlings time to mature sufficiently before planting them out in nursery beds in early fall.

Bluestem is correct, in that many of the named cultivars cannot be grown from seed. The reasons are many. In some cases they are sterile plants, and do not produce viable seed. In other cases, they set seed too late for the climate, and the seed never ripens. Still others will produce viable seed, but the resulting plants will not 'come true' to the characteristics of the parent. This group can be very interesting. I have several plants which were grown from collected seed, but are different from their seed-parents. Every year, I dig volunteer seedlings, and grow them on in pots, looking for characteristics I like. I just divided some of these for the first time, this year.

That said, there are still many many grasses which can be grown from seed, including named cultivars. Jelitto currently lists 196 different offerings, and they are one of the most well-reputed seed houses in the world.

    Bookmark   December 22, 2008 at 6:52AM
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Hi, Donn,

Where did you get your Gracillimus seeds? I can't find any at all online.

    Bookmark   February 7, 2014 at 2:19PM
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The early attempt was with seeds from a trade, and was unsuccessful. Subsequent attempts were from seed harvested from plants I bought. These plants have also self-sown.

The results are mixed. While they are all fine-bladed grasses, the offspring vary in fineness, and are not all exact duplicates of the parent. I'm concentrating on selecting the finest blade examples, and now have some with much finer blades than the original parents.

    Bookmark   February 10, 2014 at 12:30PM
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Wow, even finer? I'd love to see pics. I'm getting some in a trade, too--I'll try planting a lot more than I need and keep only the ones that come up with the finest blades. Have you tried starting them indoors early? If so, has that given you a head start, growth-wise?

    Bookmark   February 10, 2014 at 1:12PM
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