Shadow King® Rex Begonias

BEG Rex Shadow King Black Cherry
Begonia Rex 'Shadow King® Black Cherry’ PP24717

Although Rex Begonias are known as indoor plants, we use them successfully in containers and in shady landscape applications. They love low light, come in bright colors and interesting textures, and we sell cultivars that are not finicky. The Rex fanbase is large and vocal, so it has a built-in audience that appreciates them. However, picking a “good” Rex beyond ‘Escargot’ is a tricky affair.

For this job, we turn to the Shadow King series. These Rex Begonias focus on the industry professional, but they are not magic bullets. Because we would rather design to a plant’s strengths, we try to understand the breeding “under the hood”. So let’s dive into what makes this series tick.

BEG Shadow King Cool White
Begonia Rex ‘Shadow King® Cool White’ PP24738

Shadow Kings were introduced to the industry maybe seven years back, but their breeders have a long history with Begonias – Koppe in the Netherlands and GreenFuse in California. The series began with a private collection of Rex Begonias that showed promise. Several generations later – Luther Burbank-style – they developed into the Shadow Kings.

So, these Begonias were not an accident of history. They were bred specifically for the horticultural channel, picked out from promising stock. They mature to about 8-12 inches in height, spread about 6-inches wide, and show a consistent shape among all the names. Disease resistance is stronger; and their care needs are not as great.

BEG Shadow King Cherry Mint
Begonia Rex ‘Shadow King® Cherry Mint’ PPAF

However, “low-care” is not “no-care”. For example, let’s look at the roots. Rex roots are very shallow, which explains why some cultivars tip or sprawl. Shadow Kings were bred for a deeper root system, which helps the plant sit upright and present better. However, “deeper” doesn’t mean “tap root”. They still grow horizontally along the soil surface, so you want a good layer of summer mulch over the top. There is a good chance the roots will grow into that mulch over the season, and the plants will be happier for the water the multch conserves.

Their roots require loose soil or a prepared bed. They can’t cover up construction scrapings and they won’t open up heavy clay soils. However, their roots are fiberous, so they do like a wet-to-dry cycle typical of commercial accounts. They are not finicky about their water, so long as they get some – less than impatiens, but more than lantanas. One warning: Shadow Kings respond directly to soil temperature, so you want to plant them when the cold and frost is out of the soil. Otherwise, they sit and do nothing until the warmth comes in.

BEG Shadow King Pink
Begonia Rex 'Shadow King
® Pink’ PPAF

On our property, we would put the Rex Begonias underneath that Magnolia tree where the shade is deep. Other situations would include dark corners of a commerical plaza, a well-shaded porch or deck, or anyplace that has a canopy overhead.

You can do a mass planting with Shadow Kings, but they also mix well to create a full-rounded shade garden. We’ve seen them with other types of Begonias, Streptocarpellas, Hyperions, low-growing Coleus and even surrounding taller Calocasias and Alocasias.

BEG Shadow King Strawberry Sherbet
Begonia Rex 'Shadow King
® Strawberry Sherbet’ PPAF

These same plants also work in large urns, boxes and planters. They play well with the other kids, grow to their mature size and then stay put for the entire season. They don’t overwhelm the other plants, and they don’t underwhelm the viewer. They do their job well in that middle “filler” area. So long as we are looking at good shade, Shadow Kings will work.

We sometimes see them in places like lobbies, hotels, restaurants, and other areas where a business will welcome the public. Interior light is just their ticket. In fact, the low light helps the colors become more vivid as a result. Strong light will wash out colors and eventually scorch the leaves.

In small containers, we usually see them paired with exotic pottery where the plant is a specimen in itself – the leaves becomes a show set on a beautiful stage.

BEG Shadow King Wintergreen
Begonia Rex 'Shadow King
® Wintergreen’ PPAF

For a crop review, we have said very little about the colors; but that’s what draws the folks in. The photos speak for themselves. We would like to give a shout-out to ‘Black Cherry’, a personal favorite of the breeder. We also like ‘Cool White’ for its textured gray looks – that medium tone is a hard color for a plant to nail. It looks fabulous as an accent.

We offer these cultivars in our 4.5-inch pot:

  • Black Cherry—ruffled deep red leaves are edged in black
  • Cherry Mint—heart-shaped leaves are rose red with cool gray-green splotches and black veining
  • Cool White—serrated leaves are steely white with faint green veining and hints of raspberry
  • Pink—solid pink leaves have serrated gray-green edges and occasional tinges of black
  • Strawberry Sherbet—multicolored leaves with red and green patterns
  • Wintergreen—pale green leaves with jagged edges tinged copper and black veining

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Diefenbacher Greenhouses is a supplier of annuals and creative green goods. We sell directly to Garden Centers and Landscapers in the Cincinnati Area. 

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