i would guess that most of the plants that are no longer commercially available have fallen victim to trends.

one of the big garden blogs had a post about searching for the proper "ye olde thyme" mock orange. how if you find 40 year old shrubs, they are pretty different from the ones grown today, less showy and more fragrant.

The Plant Locator - Western Region lists Hammond's Acres of Rhodies for 'David'.

"More fragrant" might be Philadelphus coronarius, which has far from disappeared.

i would guess that most of the plants that are no longer commercially available have fallen victim to trends.

I think that accounts for a lot of it :-) Plants go through periods of popularity just as do other consumer products - what was popular 25 years ago has been replaced with something different. And many of those 'old fashioned' plants have just been superseded by selections that are less problematic/disease or insect plagued or that stay in more appropriate scale to local urban gardens. Personally, I find the lack of current popularity of some of these plants to be a good thing....like pfitzer junipers for example :-) Now if we could expand that lack of interest to purple leaf plums, I'd be a happy camper!

And too, over the years so many new introduction have come on the market that offer superior attributes or less common, even unknown, plants have been introduced to American gardens by folks like Dan Hinkley that the choices have multiplied exponentially. Growers produce and nurseries sell what is in demand. If the public is no longer interested in a particular plant and the demand is not present, there is no economic advantage to growing it or offering it for sale. And economy still drives the industry.

I'm so sorry I planted a purple leaf plum back in 1993. Dang thing is either covered with aphids or fungus and drops leaves constantly. It also suffers major damage during ice storms but not enough for DH to justify taking it out.

At least I didn't plant any Photinia

I could make a list of plants that I think should go out of style, and it might be even longer!

Of course anything I propagate, old or new has to go through a screening test where it must answer such questions as 'will anyone buy it' 'does this plant deserve another chance' and 'do I think it is cool?'

'Innocence'

Perhaps the most fragrant of all the mock oranges

Here is a link that might be useful: Spring Meadow Nursery - Plants - P

Sounds like a great project, Ian! I have seen histories of horticulture for California, but not for here.

One factor in plants dropping from nursery inventory is patents. If a nursery has a choice between propagating a common, older, unpatented variety and a newer patented one that they'll get a royalty from, they go with the one that will bring in extra income in the form of royalty payments. So you'll see an old rhodie or rose cultivar drop off the market and be replaced by a practically identical-looking, newer, patented cultivar.

How plants respond to propagation methods matters too in what stays in the trade and what disappears. Market forces, same thing that's pushing out indie nurseries in favor of big box stores, require that plants be propagated on a large scale and all the same way. Plants that require specialty treatment tend to get dropped from inventories because they're more expensive to propagate, and you can't always recoup those costs if the customers won't pay more.

I have noticed that the indie nurseries that used to propagate their own material, aren't anymore. It's become too expensive, much cheaper to just buy stuff in from the large producers. Retailers buy finished plants, and the production nurseries buy in rooted cuttings and tissue-cultured plantlets, and that narrows selection. Hammond's Acres of Rhodies still propagates his own stuff from his own mother plants, so he has rhodies no one else carries anymore.

Some of the very oldest garden plants in this area, were selected because they could survive the long slow arduous journey cross continent in a wagon train, and were worth carrying all that distance. Plants that came a little later had to survive onboard a sailing ship from China or through the Panama Canal. Not an issue in our selection anymore.

And some of those older, easy to transport plants have turned out to be invasive! like Gardener's Garters, purple loosestrife, and now butterfly bush. Other plants aren't worth a nursery's time because they're so easy to propagate that no one will pay money for them, like walking iris, nigella, common bearded iris, and robinia. These are 'pass along' plants. You have to have a really special cultivar of these to get anyone to pay for them.

I have grown a lot of different roses over the years (decades ...) and while I adore the old garden roses I have learned to prefer the brand-new cultivars for many reasons. Better disease resistance in the newer roses, and I mean the very newest ones, like less than 10 years old. Better production, and the flowers have more substance now. They last longer, and hold up to rain and thrips better. I grew some of the earliest hybrid tea varieties for a while and while the individual flowers are gorgeous they just don't cut it in the garden compared to the new stuff. Flowers ball in the slightest bit of humidity, and fall apart as soon as they reach their peak. And the plants need much more work - more watering, more fertilizing, more spraying, than the roses that have been coming on the market in the past few years. I used to grow a rose called 'Amelia Earhart', which is a cultivar from the 1930s I think. Absolutely drop-dead gorgeous flowers, and knock-your-socks-off fragrant, but I only got ONE good flower, maybe TWO, per year. It never put out many flowers to start with, and most of them had some kind of damage from rain or dew or insects, and many never even opened all the way before falling apart. I babied that rose for years before chucking it. Same problems with the old polyantha 'Clothilde Souperb'. Compare that to 'Memorial Day', a new cultivar, which is equally gorgeous and fragrant, and I get dozens of perfect huge flowers off of it every year, with just routine watering and feeding, and I don't really need to spray it at all.

Amazing what 100 years of hybridizing can do, isn't it?

There are locally successful and enduring old garden roses and there are also new introductions that turn out not to be any good here. There are too many kinds of roses in both groups to paint with such a broad brush.

And much stock of newer kinds is produced by the large growers dominating sales to garden centers using flawed methods like incompatible rootstock and virus infected propagules (or rootstocks). Modern roses dying off to leave behind 'Dr. Huey' rootstock is very common here (and elsewhere, judging by the number of posts asking what their dark red climber etc. is).

'Dr. Huey' rootstock sprouts seen here often appear to have mosaic virus, as do plants of multiple other cultivars displayed at garden centers. One year nearly all the newly received and potted stock at one local outlet leafed out with conspicuous mosaic patterns evident, not long after flushing.

Quite a turnoff! I try to get plants that are more likely to be clean.

Green leafed loropetalum. Remember those? wasn't that long ago that was all you could get in loropetalum. Now all you can get are purple leafed varieties. I like the green ones.

Ditto smoke bush. I prefer the green leaf but all you see anymore are the purple ones.

I was just looking at a green smokebush covered in "smoke" at a nearby outlet the other day.

They had several others in stock.

Now that you mention it the green loropetalums do seem to have been largely dropped here.

But none of those are hardy anyway, purple or otherwise.