Hmmm...I bought this one, too, and interested in the answer to this one. Not sure if pinching or cutting back is the answer, but google doesn't seem to have anything, either. They sure are a GORGEOUS flower! (Course, I'm partial to anything daisy-like, anyway)

So I asked the PW people, and got this in response (the info seems like normal common sense for most plants, and nothing specific to this item, though):

The attached file will have some good information on deadheading plants. It is also available on the website. Your plant will do best if you water it when the surface of the soil is dry. When you do water make sure you keep adding water until some drains out of the drainage hole. This will insure that the entire root zone is dampened and will encourage the best root growth. I would also fertilize once a season with slow-release fertilizer and every other week with a good water-soluble fertilizer. You dont need to deadhead although you can if you want to. The plant will be an annual for you.

Please let me know if you have any other questions.

Kerry Meyer

Proven Winners

And here is the attached info on deadheading Proven Winners

To Dead-Head or Not to Dead-HeadÂ

The phrase Dead Head has a whole different meaning for those of us who are gardeners, rather than the general public out there. If you google either Dead Head or deadhead the search results will return information on fans of the Grateful Dead not the act of removing spent blooms from plants. It takes typing in ÂGardening Deadhead to get results that will be helpful in learning more about keeping plants in bloom.

I am often the person who answers questions sent in by gardeners and recently one of the most common questions has been when and how to deadhead specific plants. In this article I will give a brief summary of why deadheading is sometimes necessary, how you should deadhead, and which Proven Winners plants need deadheading.

First what exactly is deadheading? This gardening term simply means to remove the old spent blooms from a plant to help keep plants blooming longer.

Your next question is likely to be "Why does a plant bloom more if you remove old flowers?" In the grand scheme of things flowers are meant to insure survival of the species. All of the various blooms that nature developed (not plant breeders) are an attempt to insure that seeds are produced and the next generation of plants is developed. In some cases once seed has been produced, thus ensuring the survival of the species, the plant will stop blooming. There is no reason to put energy into blooming any longer.

A gardener probably figured out that removing old flowers before they produce seed will keep the plant blooming longer. This can be a rather time consuming endeavor, but many times is considered a labor of love. In more recent times plant breeders have put a lot of effort into increasing the blooming time of plants. Someone then figured out that sterile plants, those that do not produce seed, will bloom continuously even though you donÂt deadhead. These plants keep on trying, unsuccessfully, to produce seed. Rather frustrating for the plant but easy for the gardener.

As time has gone on plant breeders have put a lot of effort into choosing plants that will continue to bloom without deadheading. Sometimes this is because the flowers are sterile and sometimes it is simply because it is possible to choose plants who are prolific bloomers despite setting seed. Proven Winners tries to select plants that are prolific bloomers but still are "low maintenance," which generally means that they donÂt need to be deadheaded. Another part of "low-maintenance" refers to the fact that many of our plants are "self-cleaning". This simply means that wind or other factors will cause the flowers to either blow off the plant or simply melt away leaving no old flower to remove. Now if only my car was self-cleaning!

Choosing plants that donÂt need deadheading would certainly be the easiest route to continuous flowers. However, in some cases there will be a plant you canÂt do without, even though deadheading is required, or perhaps the sight of old blooms still hanging on to plants will be unsightly enough that you want to remove them anyway. In these cases knowing how to properly deadhead will be necessary.

In most cases when deadheading you can simply remove the old flower by pinching off the stem just below the base of the flower. This will remove the old flower and keep it from producing seed. If the flower stem is large or you donÂt want to stain your fingernails green, you may find using pruning shears or a scissors to be a better choice.

With larger stems removing just the flower may leave an ugly stem exposed. Any flower can be removed just above the first leaf below the flower head without affecting the rest of the plant. For plants that bloom with spikes of flowers this would be the preferred method. New research has recently shown that even roses perform better when old flowers are removed just above the first leaf rather than at the first set of 5 leaves.

While a good rule of thumb is always nice to have, a list of how to deadhead specific plants will be useful too. Below is a quick run down of our Proven Winners plants and some notes on deadheading.

Deadheading not necessary for Continuous Bloom

Ageratum ÂArtist®  they will "bury their dead" (this simply means the new flowers will

quickly cover the old flowers) so no dead heading is necessary. This is not true of other series of Ageratum

Angelonia ÂAngelface® - self-cleaning

Argyranthemum  removing old blooms may improve appearance.

Aster ÂSapphire  self-cleaning

Bidens  self-cleaning

Bracteantha ÂSundaze®  removing old blooms may improve appearance

Calibrachoa ÂSuperbells®  self-cleaning

Diascia ÂFlying Colors®  self-cleaning

Euphorbia ÂDiamond FrostÂÂ Â self-cleaning

Euphorbia ÂEfanthiaÂ, ÂHelenÂs BlushÂ, ÂKalipso  These plants begin blooming in early spring and by late spring to early summer they are done. Deadheading wonÂt keep them blooming longer. However, removing the old flowers once the plant has finished blooming will encourage the plant to branch more and the next spring you should see an increase in flowers thanks to a better branched plant.

Gaura ÂStratosphere and ÂKaralee  each flowering stem adds blooms, continuously to the end of the spike. As time goes on the flowering stems can get rather long and tangled. Although deadheading isnÂt necessary for continued blooming you may find that you prefer to trim back some of the flowering stems at some point in mid-summer. This will encourage new flowering stems to emerge. Flowers will be closer to the foliage and the plant will look tidier. If you choose, you can trim all the flower stems off at once, however you, should then expect a 2 to 3 week period without flowers.

Geranium ÂJolly Bee  self-cleaning

Gypsophila ÂFestival Star  It should continue to bloom without dead-heading but removing old blooms may encourage additional blooming. With any BabyÂs breath the more you use as a cut flower the more the plant branches and re-blooms

Heuchera ÂDolceÂÂ Â They begin blooming in early spring. Deadheading wonÂt keep them blooming longer. However, removing the flower stems once the plant has finished blooming will keep them looking tidier.

Heucheralla ÂStrike it RichÂÂ - They begin blooming in early spring. Deadheading wonÂt keep them blooming longer. However, removing the flower stems once the plant has finished blooming will keep them looking tidier.

Lamium ÂPink Chablis  self-cleaning

Lantana ÂTropical FruitÂÂ Â self cleaning

Leucanthemum ÂBroadway Lights ÂÂ Â Deadheading isnÂt necessary but removal of old blooms may improve the appearance of the plant.

Lobelia ÂLagunaÂÂ Â self-cleaning

Lysimachia ÂSnow Candle  remove spent flower heads for additional branching and re-

flowering on new branches

Mecardonia ÂGoldflakeÂÂ Â self-cleaning

Nemesia  self-cleaning

New Guinea Impatiens ÂInfinity®  self-cleaning

Onothera ÂLemon DropÂÂ Â self-cleaning

Osteospermum ÂSoprano and ÂSymphony  "bury their dead"

Oxalis ÂCharmedÂÂ Â self-cleaning

Penstemon ÂLilliput Rose  self-cleaning, old flower stalks may be removed if deemed unsightly

Petunia ÂSupertunia®  self-cleaning, this is not necessarily true of all Petunias. You

may want to remove old blooms of ÂSupertunia doubles since these larger

flowers sometimes remain on the plant. Leaving them will not affect flowering.

Phlox ÂIngtensia® - self-cleaning, this may not be true of all phlox

Pulmonaria ÂGaelicÂÂ Â self-cleaning

Sanvitalia ÂSunbini®  "buries its dead"

Scaevola ÂWhirlwind and ÂNew Wonder  self-cleaning

Sedum ÂGarnet Brocade®  the seed heads will remain on this summer to fall blooming

plant. Removing them will not keep the plant blooming longer. Many people consider the seed heads to be attractive and will allow them to remain on the plant throughout the winter before removing them as part of their garden spring cleaning.

Sutera ÂSnowstorm® and ÂCabana  self-cleaning

Stachys ÂSentimental Journey - self-cleaning

Tiarella ÂStargazerÂÂ - They begin blooming in early spring. Deadheading wonÂt keep

them blooming longer. However, removing the flower stems once the plant has finished blooming will keep them looking tidier.

Torenia ÂCatalina and ÂSummer Wave®  self-cleaning

Verbena ÂBabylon®Â, ÂTukanaÂ, and ÂSuperbena® - self cleaning

So there we have it. My interpretation of all this is that we can deadhead if we want to improve overall appearance (duh), but it doesn't seem as though it will improve performance/proliferation of blooms on this specific item.
I am curious as to the double-fertilizing, though. Any thoughts on that?

mmqchdygg...thanks so much for doing the research...interesting that they are so vague on the specifics....using words like "may improve" appearance...

It would be great if someone who has had them (or any variety of argyranthemums) would find this info. I have pretty much decided that I am going to cut mine back to just above the first side stems to try and promote more bushiness. Then I'll keep them fed and hope for the best. I guess I'll learn this year, and if it doesn't work out, I'll know in the future that you have to buy them full, or not at all.