There are some very large prunus pendula specimens in Longwood gardens and most are white. Or at least very pale pink you can't even tell its pink. I do not want that. I want a noticeable pink one. And no grafted ones like 'plena rosea'. Unless I can take cuttings from them?

So wait, I actually have a 'plena rosea' in my front yard. Is it possible I propagate them from cuttings? Cuz I have never heard of an ungrafted 'plena rosea' or any cherry with a cultivar being ungraftedly grown.

'Prunus pendula' isn't a real species.

Many of the flowering cherry varieties or families are written as if they were an actual species, but that's probably because the origins of many of these cherries are/were so poorly understood. The majority of them resulted from hybridization between just a handful of wild species/varieties.

>'Prunus pendula' isn't a real species<

The full combination is Prunus pendula Maxim. and it has been raised repeatedly from seed. The usually seen wild living version, with up-angled branches is P. pendula f. ascendens (Makino) Ohwi. So, yes, probably ideally the weeping version would be designated as a variant of the upright. With for whatever reason the above naming not having been replaced with new combinations that reflect this. A similar instance - depending on how, exactly Prunus pendula Maxim. originated - may be Phyllostachys nigra (Lodd. ex Lindl.) Munro and P. nigra f. henonis (Mitford) Munro, wherein the latter is the parental species, with black bamboo being a seedling variant that appears after P. nigra f. henonis flowers.

>that's probably because the origins of many of these cherries are/were so poorly understood<

Many of the Latin names used for garden forms in the past date back to a time when this was general practice, and was not limited to the naming of Japanese cherries. Today, there are only a comparative few Japanese cherries that continue to exist primarily or solely as horticultural forms - yet are still being listed as botanical entities in contemporary manuals and monographs.

>The majority of them resulted from hybridization between just a handful of wild species/varieties<

"Most are of obscure origin, some having been cultivated in Japan for more than 1,000 years. Some are hybrids, while others are undoubtedly derived from P. speciosa and P. jamasakura (P. serrulata var. spontanea). No doubt other species have also contributed to their development. Many of the older cultivars, at least, are derived from trees found in the wild, in fact, forms of P. speciosa identical to some of the Sato Zakura have been found growing wild in Japan"

- The Hillier Manual of Trees & Shrubs (2014, Hillier Nurseries and The Royal Horticultural Society, London)

My weeping Cherry Blossom always sprouts pink flowers and this year they are white. We have had a very large amount of clouds and rain, and the person at my garden center said that extreme cloudy conditions could be the root cause.

" We have had a very large amount of clouds and rain, and the person at my garden center said that extreme cloudy conditions could be the root cause. "

LOL!! Sorry to say your nurseryperson has no idea what they are taking about. If cloudiness were a source of white prunus flowers rather than pink, then every flowering cherry in the PNW would be white. And they are not!

There are various reasons why a pink flowering cherry could appear as white, including graft failure, reversion, temperature extremes (late frosts or unexpected or unseasonal heat waves) or possibly disease or insect issues.

And it might help to know that colored flowers and sometimes foliage will change color or substantially lighten in color if in too much sun. The same thing does not happen in too much shade.......colors tend to intensify out of direct sunlight.