People south of us seem to adore pentas. What luck can we expect here in central OK? Of course I'm talking annuals.
I have planted pentas, they do well here. I haven't grown them from seed, I usually just buy those as plants.
Pentas are actually perennials that perform as fantastic annuals in Oklahoma! They come in several different colors; lavender, white, red, pink, and somewhere in between. No yellows or blues.
I love them because the butterflies and hummingbirds love them, and I garden for specifically for them.
I like the tall pentas best because they attract more butterflies and hummers. The hybrids don't seem to, probably because the nectar as been reduced somewhat in the breeding process. Tall pentas, or Pentas lancelolata, get about 2' tall for me. There are dwarf cultivars, e.g., the Butterfly series, New Look series, Graffita series, and others, that are shorter.
While pentas tend to branch out a lot on their own, it helps to pinch the tips to encourage more branching, for a fuller plant.
The pest issue I have had, and it's not an issue for me as a butterfly/moth gardener, is that they are the larval host plant for the Tersa sphinx moth, a large hummingbird sphinx, a nocturnal moth that nectars on and pollinates flowers at night. They are large moths, thus they are large in the caterpillar stage of growth, and can easily consume a patch of Pentas quickly. If you don't want them, use BT-kurstaki. The larvae ingest it when eating the foliage and it causes paralysis of the digestive system, killing the caterpillar within 1-2 days of use.
Pentas can be grown in full sun to partial shade and prefer a fertile, well-drained soil, although they are tolerant of a wide variety of soils. I usually grown mine in containers, with regular potting mix. They like to be to be watered regularly. I fertilize mine about once a month with a balanced fertilizer.
I might add that Pentas LOVE the heat, which we can provide in plentiful amounts!
I love pentas too and have grown them here, but not in recent years.
I grew mine from seed for a couple of years and it takes them forever to get large enough to transplant out so you have to start them indoors really early if you want to grow from seed,
I do not grow them any more because we have too many sphinx moths here, and the poor plants don't stand a chance. As soon as you transplant them, or uncover them if you have had row cover over them to protect them until they were nice and big, the sphinx moths descend upon them, lay eggs, and the cats devour the plants and leave you big empty spots with plants eaten back to the ground. I know some butterfly gardeners have to work hard to attract various sphinx moths, but we have them in huge quanities here. Since we have the ones that like the pentas so much, I gave up growing pentas. i would have continued growing them, but they never get a chance to grow so it is rather pointless. Nothing I've ever planted here has been devoured as quickly by anything as the pentas were. I'm in a wildlife-rich wilderness though and we have oodles and oodles of sphinx moths of many different kinds. If you are in town, you likely won't lose all your pentas to the sphinx cats.
Yes, Dawn, they are large caterpillars, and large moths! Since I live in an urban environment, my Pentas aren't attacked every year. Usually every 2 or 3 years, depending on the Tersa Sphinx population.
If you want good pollinators, though, not necessarily of vegetables, but if you grow flowers like Datura, Petunias, 4 o'clocks, anything tubular in shape, would benefit from the sphinx moth family.
Here is a link that might be useful: Xylophanes Tersa Sphinx Moth