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Episode 41 – Vivacious variegation, the truth about milky spore, and plant breeder Megan Mathey

Ground Breaking Banter - Rick

Let’s talk about leaf variegation. I was admiring Weigela Vinho Verde the other day and its lime green leaves with a bold black margin.

When I think of foliage variegation, one of the first plants that comes to mind is the perennial Hosta. They have to be one of the standards for variegation in the landscape with so many cultivars and variations. For example, Proven Winners Hostas like Shadowland ‘Etched Glass,’ ‘Mighty Mouse,’ ‘Rainbow’s End,’ and ‘Fire and Ice.’ Or the splotches of variegation in Pulmonaria ‘Pretty in Pink,’ ‘Pink a Blue,’ and ‘Spot On.’

With variegation in the landscape, I believe you have to be careful or selective, or it can quickly become too much (visually).

Leaf variegation can be viewed as a special, attractive trait and has been, at times, a focus of plant breeding, as it could be argued it increases the economic value of ornamental plants.

In my experience (during 2018-2021), it certainly did with houseplants. In foliage plants, there was a craze for variegation in plants like Calathea, Aglaonema, Pothos, this year’s 2023 Houseplant of the Year – Feeling Flirty Tradescantia, and even old stand-by houseplants like Prayer Plant or Spider Plant. But it was the Philodendrons and Monstera (genetic mutations) that were highly sought after, and the prices were crazy! It was like the Tulips of Tulipmania. Viral infections can cause variations and variegations. Tulip breaking virus (TBV) played an essential role in ‘tulipomania,’ which occurred in the Netherlands in the seventeenth century. The flower break patterns in affected bulbs were highly prized and commanded huge prices. Unfortunately, the effect was often unstable, and affected bulbs did not repeat the patterns reliably in future years. The bubble burst! This rapid decline was driven, in large part, by people purchasing bulbs on credit, hoping to repay their loans when they sold the bulbs for a profit. But once prices started to drop, holders were forced to sell their bulbs at any price and declare bankruptcy.

And then there was ‘Pink Congo’ Philodendron; in the summer of 2019, it was suddenly revealed that the plant was fake – the pink leaves were chemically induced, and new growth would return to green after a few months. The houseplant community was outraged over this scam.

I love “variegated tropicals” like Cordylines or Caladiums (Heart to Heart).

Even our annual containers are in the act with Variegated Swedish Ivy Proven Accents® ‘variegata’ (Plectranthus coleoides) or Proven Accents® “Tricolor” Sweet Potato Vine.

A question for Stacey. Can low light conditions cause a variegated plant to lose its pattern and turn mostly green even when the variegation is part of the plant’s DNA? In other words, people are concerned the variegation will revert in reaction to extremes of hot and cold or a response to low-light levels.

Types of variegation: (we mentioned the virus in the tulipmania reference)

Genetic variegation (Pattern-Gene Variegation) is inherited or passed down from generation to generation. This form of variegation is the most common type since it occurs naturally. Appearing as a specific pattern on each leaf, pattern-gene variegation is not a mutation but part of the plant’s DNA.

Chimeric variegation is randomly occurring, so it is not predictable. Plants with chimeric variegation are often described as mutants because cell mutations cause the variegation. And it’s an example of words that drive me nuts! I have heard “Kee,” “Kye,” and “Kuh” (ky-MEER-ik). Chimeric means having parts of different origins. It refers to a person, organ, or tissue that contains cells with different genes than the rest of the person, organ, or tissue.

Blister or reflective variegation is a type of variegation formed by air pockets that exist between the outer leaf layer and the inner pigmented layer of the plant. When light hits the air pockets, it creates a shimmery, reflective patch that is quite stunning. Often these areas can seem sparkly or silvery. I say that one of my favorites, Satin Pothos (Scindapsus pictus), also known as the “Silver Splash” houseplant, is a great example of this.

Artificial, in this case, means that the plant does not produce the variegation within its cells naturally (whether through cultivation or natural mutation). Instead, humans add something to the plant so it becomes or appears variegated or discolored, examples being Pink Congo, painted succulents, or variations in Orchids.

More favorites of mine?

Tricolor Sage (Salvia officinalis)

Variegated Sedge plants like ‘Ice Dance’ (looks like a hardy spider plant!)

Morning Light Ornamental Grass (Miscanthus sinensis)

Color Guard Yucca (Yucca filamentosa)

Aureola Golden Variegated Hakone Grass (Hakonechloa macra)

Sunjoy Sequins® Barberry (new growth emerges as a shimmering palette of white, pink, and mint green before maturing to emerald)

My Monet® Weigela

Dappled Willow (Salix integra)

Variegated Ginger

Why: A show on variegation deserves a variegated Plant on Trial! Though we have several I could have chosen, I opted here for the OG, the original, the plant that totally upended the weigela world: My Monet weigela. There had been variegated weigela before it, but never one that had such crisp, clean, appealing variegation, and never one that also offered this same delightfully compact, rounded habit. Oh, and the lovely pink flush that develops on the foliage during cool weather. People went crazy for it! Especially when you add in its beautiful pink flowers. In many cases, the flowers on variegated plants are not very noticeable against the busy-ness of the leaves, or even detract from it. However, in the case of My Monet weigela, the late spring/early summer flowers make it even more beautiful. 

My Monet weigela is also that rare variegated plant that looks amazing in the landscape whether you plant one or dozens. And people do plant dozens! There’s something about the cleanness of its variegation that gives it a fresh, restful effect in the landscape rather than the chaotic one that often develops when variegated varieties are planted en masse. Its size and scale also make it beautifully suited to mixing in with perennials and other shrubs in mixed borders and flower gardens. 

Who: My Monet weigela was selected by Bert Verhoef at his nursery in the Netherlands. 

How to grow: Weigela are generally shrubs for full sun, but the variegation on My Monet weigela makes it suitable for shadier conditions. It can take full sun in cool climates, provided it is mulched and watered, but the warmer the climate, the more important shade becomes. If My Monet experiences water stress in the summer, it will go prematurely dormant, so for best effect, keep it cool and well-watered. It doesn’t need a great deal of fertilizer, but if you wish, you can fertilize monthly from early spring through late July using a rose fertilizer. 

Its naturally cute and compact habit means it needs no pruning to stay tidy. If you wish to prune, since it blooms on old wood, after it flowers in early summer would be the best time. If you don’t care about the flowers – and to be honest, it’s plenty ornamental without them – then you can prune in late winter/early spring, while it is still dormant. Like many variegated plants, My Monet weigela may revert, or throw out stems that resemble the parent plant it originally mutated on. These are usually green, perhaps purple, and should be removed as they occur. Because they contain more chlorophyll than the variegated version, they are likely to be stronger and more vigorous and can overtake the plant if left unchecked. Simply snip out as close as possible to the base of the plant as they occur. 

Weigela, including My Monet, is deer resistant. 

If you’d like to add My Monet weigela – or any of the 320+ Proven Winners ColorChoice Shrubs – to your garden or landscape, you’ll find a list of local retailers here

Gardening Mail Bag - Stacey

This is such a great question, and I learned so much trying to answer it for you! Here’s what I have to share: in short, no, milky spore is not the best way to break the cycle of Japanese beetles, but can play a role in breaking the cycle. If you aren’t familiar, milky spore is a bacteria, that, in the 1930s, was discovered to kill Japanese beetle larvae – grubs – if they ingested it. It derives its name because it turns the grub from a clear yellow to a milky white. It is only effective on Japanese beetles, not any other types of grubs. The grub stage of their lifecycle lives in lawns, and the milky spore is applied to the lawn where it goes into the soil and the grubs hopefully consume it as they feed on roots, algae, and so forth. Sounds great in theory, but in reality, it’s not quite so simple. For milky spore to be effective, it has to be present in the soil when the grubs are actively feeding in spring and fall, the grubs have to physically ingest a minimum quantity of spores, and the temperatures must be 66-70°F. Very often, these conditions don’t line up, especially in colder areas where spring can be quite cool. That said, it’s worth applying milky spore in spring – exact directions and timing will depend on the formulation, so read your package directions – and working toward building up a population of milky spore in your soil to increase your chances of success. If you are digging in the garden and encounter any milky white grubs, leave them in the soil – their body will release more spores and help build the population of milky spore in the soil. So yes, work toward building up milky spore in your soil if you have a Japanese beetle problem, but pair it with other adult management strategies, like handpicking, spraying, and planting resistant plants. 

Nothing you are doing wrong, Bill – they just need time! Lavender is extremely slow to grow from seed, partly just due to its nature and partly because woody plants generally take more time to grow from seed, especially if they start from a seed as small as that of lavender. Make sure they get plenty of sun and warmth and they will eventually take off. Though growing lavender from cuttings is much faster, there’s little that compares with the satisfaction of looking at a beautiful plant you grew yourself from seed. 

Do you have a question for us? We’re happy to help! E-mail us or use the contact tab above.

Branching News - Rick

In this episode, we’re joined by Proven Winners ColorChoice plant breeder, Megan Mathey. Join us as Megan explains just what, exactly, a plant breeder does, how she got interested in the field, and her favorites of the shrubs that she has developed so far. 

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