How thoroughly do "they" test out hardiness on new plants?

christinmk z5b eastern WAFebruary 4, 2013

I sort of offhandedly said this on my thread about Geranium 'Ann Folkard'. The more I think of it, the more curious I am about it. I'm sure someone out there has the answer...

I'm interested to know how the process goes "behind the scenes". How much do "they" really test out and analyze the hardiness (and other factors of course) of a new plant? Do they do it in many locations besides their own? Do they do it over a length of time, or one winter before rushing it out onto the market (sort of seems like they rush it for some of them nowadays doesn't it?!)? Or do they even skip this if they figure the parents involved are hardy, so should the offspring be too? What is the criteria for this process?

I've read of individuals in the buisness and smaller nurseries/companies sending their plant in development to fellow plantsmen/nurserymen (etc) they know to trial and report their findings and thoughts. Is it the same with professional hybridizers and large companies? Do they perhaps send samples of the plants to various trial gardens around the states (or wherever...) for evaluation?

Very interested to learn how the hardiness zone is decided for individual plants. Thanks!

Thank you for reporting this comment. Undo
aachenelf z5 Mpls

Good question and I'm curious what others have to say. I remembered the following post to another thread I started:

kimka posted:

"Some genuses have Societies that are now doing independent testing for cold hardiness. But there is no real convention for using a particular amount of exposure as the basis for rating a variety--single night vs. multiple nights. Also, hardiness really depends on when the cold exposure comes. If the plant has a chance to be conditioned to colder temperatures in a gradual slide, it will be better able to survive than a sudden drop to a cold temperature.

There is more scientific convention about the hardiness of agricultural crops, but it is still pretty loose.

Mostly I think ornamental plant breeders just grab the hardiness zones on record for the species of a plant and who knows how precise those really were when they were recorded.

That's one of the reasons I peruse and often buy from very reputable mail order nurseries like Plant Delights, who do a lot of their own testing of new varieties and tell you what they've found and if it differs from the label given by the breeder.

I know this isn�t new information for many gardeners, but I thought I�d confirm what most of us believed."


    Bookmark   February 4, 2013 at 3:55PM
Thank you for reporting this comment. Undo
christinmk z5b eastern WA

Very interesting that plant societies are doing independent evaluations. Think I would tend to trust their (and fellow gardeners) findings more than the developers or companies that put out the plant. Just like one takes the findings of drug studies funded by the maker of the drug with a grain of salt. LOL.

I'm not sure...if a plant is TRULY hardy why would it need gradual reduction in temperature vs. a fast one?? Maybe it is in regards to a less-than-hardy plant? Our autumns do not linger here, sometimes a frost pounces hard on us overnight. Perhaps I am wrong, but I wouldn't think that a sudden onset cold is much of an issue, unless the plant had yet to fully establish itself?

    Bookmark   February 4, 2013 at 4:31PM
Thank you for reporting this comment. Undo
Patty W. zone 5a Illinois

One place that throughly test their introductions is Chicagoland Grows. Many botanical gardens test out plants. They're no longer new intros however when testing is done.

    Bookmark   February 4, 2013 at 6:47PM
Thank you for reporting this comment. Undo
ken_adrian Adrian MI cold Z5

oh you guys crack me up..

and who exactly is paying for this testing???

they drop the cultivar name.. and CLAIM!!!! ... hardiness equivalent to the species..

and i bet thats it .. period ...

of what difference would the cultivar make in hardiness anyway

i once asked a hosta TC'er.. how they took TC sports.. and with never growing them out to maturity.. started selling them 2 years later.. with DEFINED SIZES ...

he said.. well ken.. whatever the sport popped out of.. was grown to that size ...

i said what if the plant has all white centers.. it will be weaker.. less vigorous.. he said yes.. but it will never be bigger .. lol ..

i said ok .. so the bottom line is that tags and labels and books simply WING IT ... he said.. yes.. basically ..

who tests.. lol.. yeah right .. good luck with peeps doing that for free ..


ps: the only testing i ever recall hearing about.. was JP MORGAN [??]roses.. and their all American series.. which was supposed to be able to be grown.. all over America.. and they actually sent out plants years in advance.. and only those that grew everywhere.. got the award.. and the designation ...

    Bookmark   February 4, 2013 at 7:03PM
Thank you for reporting this comment. Undo
mistascott(7A VA)

I don't know the answer to your question, but I will say this: The word "hardy" can mean many things. To some it means merely surviving winter. To others, it means "tough" or able to face brutal conditions well.

I hate hardiness zones because they capture a single piece of information (temperature) and they do so without much precision (the 5 degree temperature range in which your yearly minimum temperature usually falls). It tells us nothing about snow cover, wind, precipitation (wet vs.dry), cloud cover, duration of arctic cold, or the many other factors that can affect a plant's winter survival. Moreover, there are many site-dependent factors that can affect survival as well such as whether the plant is in a wind-shielded southern exposure or a wind-battered northern one. I do think that hardiness zone is a decent proxy for the overall harshness of the winter, but I think gardeners (and probably growers and plantsmen too) give zones too much weight when making decisions about what to buy and sell.

    Bookmark   February 4, 2013 at 7:12PM
Thank you for reporting this comment. Undo
mistascott(7A VA)

I do know that many plants are specifically hybridized to establish better hardiness and the attempts at this are thoroughly tested. Just Google the story of the 'Chuck Hayes' Gardenia cultivar down in Virginia Beach as an example.

    Bookmark   February 4, 2013 at 7:19PM
Thank you for reporting this comment. Undo

"They" and "hardiness" are the big key words here. How much testing of new varieties depends on the "they". Most large companies (Walters, Terra Nova, Weeks Roses, Star Roses, Bailey Nursery, Spring Meadow) do pretty extensive trials, the companies themselves pay for the trials (that cost is worked into price of the wholesale plant- passed on to the grower which is then passed onto the consumer- you!). Most botanic gardens have trial gardens for new varieties that suppliers take part in (taxpayers or visitors pay for the testing here). Traditionally hybridized varieties technically aren't new either. It can be 5-10 years before a "new" variety hits the market. Some plants, like Heuchera, can be tissue cultured once a selection is made and the resulting plantlets can be raised to maturity much faster than allowing a normal growth from seed to adult. Heuchera may hit the market in 3-5 years. TC mutations from Hostas may not be trialed very long, and sizes are often estimations. And in most cases those estimations aren't very far off. Lastly, better retailers (someone mentioned Plant Delights already, Klehms, Rare Find, Arrowhead Alpines, and many more including my own nursery) do trials.

Hardiness relates to many factors, even if we're just talking about a plant making it through the winter. Most new Agastache are given a fairly conservative hardiness rating of zone 6 or even zone 7. With the proper soil (very well drained) most will survive zone 5. Same goes with Heuchera, and the Echinacea hybrids. Growing conditions are everything, plants that are unhappy don't live long.

Lastly, don't believe tags... look for the research. Most tags are full of crap. You'd think that R&D and Marketing departments would communicate, but they too often don't. Visiting a GOOD retailer (not a box store) can go a long ways to giving you correct information.

The Plant Geek

    Bookmark   February 5, 2013 at 2:15AM
Thank you for reporting this comment. Undo
ken_adrian Adrian MI cold Z5

Most tags are full of crap. You'd think that R&D and Marketing departments would communicate

==>> i further asked my guy.. who was one of the above mentioned wholesalers..

why his tags still called hosta ... funkia.. since that term went out of use decades ago ... right up there with plantain lily ...

and he said.. because decades ago.. they had a quarter million tags printed.. and they were still trying to use them up ... lol ...

and do not get me wrong.. props to the breeders who do this stuff .... like the above mentioned chuck hayes .... and it is up to you to do the research to find such plants ...


    Bookmark   February 5, 2013 at 8:01AM
Thank you for reporting this comment. Undo
kimka(Zone 6B)

Some groups like the the All American Selection winners actually have trial ground all across the country. You can even visit the trial gardens ( But that's just for their award.

Even breeders who do trial for plant hardiness are at the mercy of what the weather was like that year or two. If they had a warm winter across much of the country that is really going to affect how they see the hardiness of their new variety. Most commercial breeders just can't invest in long term trials in multiple locations.

Sophisticated nurseries like Plant Delights and a few others often say in their descriptions if they seen something different in hardiness, light needs, even moisture needs. But of course you have to translate that from their location to yours.

That's one of the things that forums like this have provided: an aopportunity to hear from lots of other gardeners about how plants are doing under what conditions.

The new 2012 USDA Plant Hardiness Map allows you to see your location down to about a quarter of a mile and get the exact average low temperature to the tenth of a degree as well as your more general zone in an A and B split. For most plants a 5 degree spread is within their tolerance. So you can get your zone not only pretty precisely, but see how close you are to the edge of your zone. Of course, there are other factors to complete hardiness, from duration of the coldest to snow cover etc. When Sunset magazine tried to take more factors into account, they ended up with something like 45 climate zone. And the factors they took into account are pretty rough in scale.

This post was edited by kimka on Tue, Feb 5, 13 at 14:45

    Bookmark   February 5, 2013 at 11:21AM
Thank you for reporting this comment. Undo

The "they" I depend on for hardiness testing of new introductions is you - the gardeners who post their experiences in forums like this one.

I generally avoid being among the first to shell out for a new plant, especially when the species and/or related hybrids have an iffy reputation for making it in my climate, or when the hybridizer has previously laid some eggs.

From listening to others b*tch and moan about unexpected failures, I can avoid wasting time and money on plants that were prematurely rushed to market. :)

    Bookmark   February 6, 2013 at 4:37PM
Thank you for reporting this comment. Undo
katob Z6ish, NE Pa

Like others have said tissue culture changed things a bunch.... 3-5 years to bring a new heuchera out on a national (and sometimes international) scale means going from one plant to hundreds of thousands in something like 40 months. Maybe there are some field trials etc going on but it's nothing even close to the days when plants spent years multiplying and growing in fields here and there.

I supposed that's the tradeoff for mass avaliability of new plants, you get millions of outdoor plants that have never actually grown out of doors.

I also get a lot out of the experiences of others found here, thanks! I know I saved a couple bucks on all the limerock beauty coreopsis that I never bought!

    Bookmark   February 6, 2013 at 8:08PM
Thank you for reporting this comment. Undo

The nice thing about Heuchera, is that fast TC process gives you a mature plant in 3-4 years quite easily. The hybridizer and grower understands what the plant is going to do before it hits market. Year 5 is release. USUALLY it is longer than that, but in the best case when you have a definite winner it can be that quick. While it is very much possible to get hundreds of thousands in 40 months, that's almost never the case. It's always a limited release the first year or 2. At my last job I was the buyer and grower, trust me, it's a TOTAL PITA securing new varieties. Heuchera are easy to grow and IN GENERAL (lets face it, there are always exceptions) all varieties prefer a certain set of growing conditions. So there isn't this terrible need to trial them nationwide for gardenworthiness. Much like hostas, or daylilies... easy to grow if you give them the right conditions. The problem comes in that the gardening public isn't always educated correctly. Not a dig against the gardening public, education is OUR (horticulturists collectively- I do my best) responsibility. Sometimes we do a bad job (IMO my industry failed miserably with the whole hybrid Echinacea thing, and those were definitely a long trial time, despite what people might think). Terra Nova has done a pretty good job with giving what species are in a given variety's background. If it has strong villosa breeding you know it's going to tolerate more heat and humidity and heavier soil. If it is mostly micrantha, it will probably suffer in winter in the far north and in high heat/drought. But in general, Heuchera want gritty soils. They like excellent drainage, period. Even villosa, pubescens, and americana (woodland dwellers) derived varieties really appreciate a gritty soil.

The whole Limerock Ruby Coreopsis thing is a whole other story... basically 1 nursery making an entire industry look like Aholes with a capital A by NOT trialing a plant and giving false information about hardiness. It's still hard to sell new Coreopsis, despite some of them being bigtime winners. 2 great ones: Route 66 and Star Cluster.

The Plant Geek

    Bookmark   February 7, 2013 at 1:17AM
Thank you for reporting this comment. Undo
calistoga_al ca 15 usda 9

Most of us have had the experience of plant damage, when the plant has experienced no damage other years, when the temperatures were even lower. What will often make the difference is just how long, or how many hours, was the temperature below the rated tolerance of the plant? It is not always the rating that was at fault. Al

    Bookmark   February 7, 2013 at 10:07AM
Thank you for reporting this comment. Undo

Bit of a side question here: how important do you find "provenance" to be (where a plant has been grown)? For instance, does it make a big difference in your garden if the source of the species (or hybrid) is a northern nursery as opposed to a southern one?

There are supposedly documented cases of subspecies (for instance, Cercis canadensis) which do better in certain climates and presumably have differing genetic makeup to account for it. But I wonder if this mantra has a tendency to get overhyped without solid supporting evidence.

(I'm going to find out before long in the case of a seedling batch of Eragrostis elliotii that I'm currently raising indoors. This perennial grass has a wide growing range, from the deep South up well into zone 6 if the wintertime drainage is good. My seed is from Florida, so we shall see).

    Bookmark   February 7, 2013 at 1:11PM
Thank you for reporting this comment. Undo
christinmk z5b eastern WA

-plant geek, wonderful info. Thanks much for sharing.

-Eric, Good question. Hope someone comes along with more experience that can help sort that out.

My thoughts on it...I worked at a nursery last year and the manager said some things did very poorly (arbs for one, go figure!) at over wintering because they were from CA. Not sure if there were other circumstances involved for their poor ability to overwinter (like late planting, etc).

I'm not sure how long it takes a plant to evolve enough change the hardiness and genetic makeup of it. Evolution like that takes time, but I would think awhile? Like hundreds/thousands of years, each generation passing the traits onto the next?

I would think the nursery source is something like growing hardy plants in a hothouse. Hardy plants grown in a hothouse need hardening off, but once they are they can be planted outside and survive. The cold hardines is still hardwired into them, so once they get over the initial change of temperature shock they are okay. I would imagine it would theoretically take hundreds/thousands of years of growing in that hothouse to end up REQUIRING those conditions? Just thinking out loud here I guess, lol.

I think the case of the Cercis is relating to "disjunct" plants. Populations of plants had a wider range some thousands of years ago because of warmer temps, then when things began to cool some groups developed a greater cold tolerance than those of the main populations we see today. These separate groups are known as "disjunct". Think it can also happen the other way too, some isolated groups can develop a greater heat tolerance over the years.

Guess it really all depends on where the original source it came from, if it was one of the colder or warmer groups! There was a great article about this in the Jan/Feb 2012 issue of Horticulture magazine...

    Bookmark   February 7, 2013 at 2:48PM
Thank you for reporting this comment. Undo

Provenence is one of those misunderstood factors. Provenence is important if talking about wild collected material. It can make a big difference if a plant is collected at 2000' elevation and say again at 10000' elevation. The plant at the higher elevation is likely to be more tolerant of cold. Same with a wide ranging species. Collect one in Florida and one in Minnesota. Which one will (probably) be more cold hardy? Now make a selection based on that one collected in MN and grow it in FL, CA, GA, WI, or wherever. Besides acclimating to the current season (you wouldn't bring a plant from CA to WI in March and expect it to survive without protection for example) it will have the hardiness of its original provenance. So Oregon grown nursery stock of Cercis canadensis MN strain will be just as hardy in MN as nursery stock grown in MN.

Easiest thing to remember is provenance is the plants origin, not where it was grown. They're 2 completely different things.

The Plant Geek

    Bookmark   February 7, 2013 at 11:44PM
Sign Up to comment
More Discussions
hey newbie: is not a green thumb you want .. its a ....
brown index finger ....[keep your head out of the gutter] i...
ken_adrian Adrian MI cold Z5
Does Anyone Do Mixed Perennial Containers For The Deck/Patio?
As opposed to annuals? I've been seeing some pretty...
Names of these two plants?
Can someone help me with the names of these two bushes?...
Trillium 2015
This thread is for anyone who wants to post pics of...
NEWBIES: dealing with heavy clay soil
i praise the Lord.. i have never had to deal with it...
ken_adrian Adrian MI cold Z5
Sponsored Products
Bracken Fern with Decorative Vase Silk Plant
Red Faux Silk Flower Drop Window Valance
Owl Butler Umbrella Stand
| Dot & Bo
D and W Silks Oxalis Ivy in Square Bamboo Planter - 104006
$31.99 | Hayneedle
Casa Cortes Flower Bloom Three Dimensional Metal Art Wall Decor
2-Pc. Cube Planter in Cobalt
$9.99 | Dot & Bo
Parquetry Driftwood Nesting Tables - Set of 3
| Dot & Bo
Jaipur Metro Adonis Area Rug - RUG112622
$62.00 | Hayneedle
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™