Episode 48 – Plants and sunburn, a shrub that lights up the night, and transplanting perennials

Ground Breaking Banter - Rick

The Norwegians (and Minnesotans) have a saying for people: “There’s no such as bad weather, only bad clothes.”
It could perhaps be said for plants that there is no such thing as bad weather, only bad placement.
With the extreme heat in some regions this summer, there have been a lot of news stories about how weather is affecting plants, like this one about saguaro cactus in Arizona or this one about olive trees in Spain

So what about sunburn? Plants need its light to photosynthesize and hence say alive, and to withstand periods of intense light and heat, they produce a kind of natural sunscreen like a sunbather on the beach, protecting themselves from damaging rays. Of course, some plants are more adept at adapting to sun than others, and shade plants can have two reactions to too much sun: their leaves can bleach or they can scorch. Bleaching is caused by excess light, but not excess heat. It occurs in cool places or at cool times of the year. The leaves that are receiving too much light become pale green, yellow, or light gray. Shade-tolerant plants are adapted to be efficient energy-users. In simple terms, shade-tolerant plants grow broader, thinner leaves that shade the roots.

Scientists have known for sometime that plant cells have a protein called UVR8 that can detect shorter wavelength UVB rays, which is the type of UV radiation most responsible for sunburn. This protein signals the cells to begin producing compounds that block further UV damage and repair DNA damage.

In 2014, researchers at Purdue University identified one of these protective compounds as sinapoyl malate and found that this molecule harnesses quantum mechanical effects in order to absorb UVB rays. They say the ability to produce this natural sunscreen seems to be common to all land plants and algae, which suggests it is an ancient adaptation. Plants aren’t invulnerable to the Sun, however. Prolonged exposure to the UVB in strong sunlight causes cell damage to the leaves and bark of many plants. This is worse when plants are dehydrated, because this limits their ability to move sunscreen chemicals to the worst-affected sites.Ironically, there is a widely-held belief among gardeners that watering plants in the midday sunshine can cause sunburn, because droplets of water supposedly act as tiny lenses to focus the sunlight onto the leaf surface. However, this myth was debunked in 2011 by researchers at Eötvös University in Budapest, Hungary. They used computer modelling and direct experiment to show that the refractive index of water isn’t strong enough to focus sunlight from a water droplet onto the surface of a leaf.

Why: When the sun is at its most intense and the heat is on, you can count on butterfly bush to ride it out with aplomb. Pugster White buddleia is an especially nice choice when it comes to butterfly bushes for hot weather because the white flowers bring a cool, refreshing look to the landscape or garden. White is often underrated as a color to add to the garden, but it can do so much – it’s the perfect choice when you don’t know which color to add, and at night, it seems to glow or shine out from the garden, bringing a magical quality. Plus, white flowered butterfly bush tend to attract night-flying moths. If you are thinking, yuck, why would I want to attract moths? Please allow me to change your mind…they are beautiful, amazing creatures and you can almost think of them as the furrier version of butterflies. Speaking of butterflies, of course, Pugster White butterfly bush attracts them as well. 

Who: The Pugster series of butterfly bush, including Pugster White, was developed right here in West Michigan at the Proven Winners ColorChoice Shrubs HQ. 

How to Grow: Not surprisingly, the key to success with butterfly bush is sun – lots of it! At least six hours of bright sun each day. The second key to success is well-drained soil. If you have clay soil, plant your butterfly bush slightly higher than, rather than even with, the soil level, and do not amend the soil when you plant. Avoid overwatering them. Cold, wet soil in late fall, winter, and early spring, when the ground isn’t frozen, is the biggest threat to butterfly bushes, so avoid planting them in areas where they will have heavy mounded snow on them, or where they will get dripped on by melting ice and snow.

Proven Winners ColorChoice butterfly bushes do not need to be deadheaded in order to bloom continuously, but they do benefit from pruning in spring. This not only helps keep their habit appealing and compact, it also ensures the plant flowers from bottom to top, instead of just way up at the top like an unpruned butterfly bush would. 

If you’d like to add Pugster White butterfly bush – 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

If something is going wrong with the top of your plant, the answer almost certainly lies in the roots. A plant can only grow on top as much as its roots can support, so a lack of top growth generally indicates a proportional lack of root growth. This can be due to low water, damage from voles, mice or other animals, underlying obstacles like rocks or concrete, to name a few possibilities. It’s also worth considering how much sun they get – peppers need full, bright sun to grow well. That said, if they were getting too little light, the plant would be more likely to stretch and get thinner and taller than not grow at all. Two last factors to consider as to why your pepper plants are stunted: first, were the seedlings planted in peat? Are the plants in peat now? Research shows that peppers do not grow their best in peat. Second, fertilizer. As with most crops that produce fruit, a fertile soil is crucial in providing the resources the plant needs to flower and fruit. Personally, I fertilize all of my vegetables weekly or bi-weekly during the growing season, and would suggest the same for your peppers.

Yes! Fall is a great time to transplant strawberries and most perennials and shrubs. Ideally, you want to save this task for when the weather has cooled and the nights are longer, and so that the plants have time to recover and grow roots into their new home before really challenging cold weather hits. Aim for at least six weeks before your ground freezes to finish your transplanting; sooner is fine if weather permits.

Wow, so many choices – how much time have you got? When it comes to shrubs, of course, hydrangeas are essential, and I recommend dwarf panicle hydrangeas in particular. They’re very hardy, can be used at several stages, dry well, and the dwarf varieties are easy to keep in scale with most vases and arrangements. The truth is, though, that many shrubs and perennials have potential as cut flowers. Even if not as flowers, then often as foliage, seed heads, or berries. Here’s a list of some great perennials for cutting gardens (unfortunately, not all of them are hardy to USDA zone 3), and here are some shrubs you can consider. But ultimately, the best way to choose is to visit a local garden center and just see what catches your fancy. Enjoy the journey!

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

Branching News - Rick

Join us as we interview Brie Arthur, Brie the Plant Lady. We’re sure you’ll enjoy her enthusiasm and unique perspective on gardening as much as we did! She freely mixes edible and ornamental plants in her landscape and containers, and shares some of her favorite edible-ornamentals with us, including ‘Cream Sausage’ tomato. You can catch our interview with her on our podcast or our YouTube show below, and if you’re on YouTube, explore more of Brie’s plant world on her channel

Photos of ‘Cream Sausage’ tomato and purple rice courtesy of Brie Arthur.

Special bonus! Join Rick and Stacey on a tour of the Proven Winners ColorChoice trial and display gardens:

Pink rose of Sharon flowers bloom on a plant with variegated foliage.

Episode 92 – Weeding by Example

Ah, weeds – maybe the #1 thing that discourages people from gardening. But weeds are interesting and become a lot easier to manage when you apply some basic IPM principles. Featured shrub: Sugar Tip rose of Sharon.

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