Archive for May, 2011

Sam's colorful container garden

Yesterday afternoon, Sam Harris of Sam Harris Designs came to the nursery to do a workshop on container gardening. It was really fun to listen to him and watch as he created the most amazing “garden” in the giant urn that has become one of the focal points in the Viette Garden Center.

Sam combines perennials like this bright pink ice plant, Sedum 'Angelina', daylilies, and even a colorful Caryopteris 'Hint of Gold' with annuals.

Sam combines perennials like this bright pink ice plant, Sedum 'Angelina', Salvia, daylilies, and even a colorful Caryopteris 'Hint of Gold' with pink petunias and 'Diamond Frost' Euphorbia.

It’s not just that he created an incredible, show-stopping masterpiece, it’s how he went about doing it and what he put in it! I was astonished that about 60-70% of the plants he used were perennials. I have never really thought about putting perennials in my containers but then I really just have small hanging baskets off my deck.

Sam prefers to design giant container gardens in great big pots or huge cement urns like the one in our garden center. “If I’m going to create a container garden, I want it to be seen – not just close up but I want it to WOW people from a distance!” And that’s what he does. Sam has designed beautiful gardens and containers for many businesses as well as both private and public homes including the Gillette Garden at the Executive Mansion in Richmond.

Good soil prep and good drainage are key to a successful container garden.

Good soil prep and good drainage are key to a successful container garden.

The secret to a successful container garden, according to Sam, is good soil preparation. For the planting medium, he prefers to use a mixture of pine fines (finely ground pine bark) and a quality potting mix like Scotts Miracle-Gro Potting Mix, Espoma Organic Potting Mix, or ASB Greenworld Container Mix. After planting, he always gives the plants a shot of Miracle-Gro Quick Start to give them a boost and to prevent transplant shock.

Perhaps just as important as a good soil mix is the presence of a drain hole in the container. Nothing kills (most) plants quicker than waterlogged soil! Before filling your container, place a piece of nylon window screening or landscape fabric over the drain hole. This keeps it from becoming clogged with soil. Sam actually likes to use a plastic pasta strainer or even a sink strainer over the drain hole in his containers. On top of this he recommends layering some lava rocks and then some pine bark nuggets to provide additional drainage. After this, fill your container with your potting mix and you’re ready to roll.

Now comes the fun part – choosing the plants!

With an artful eye, Sam placed perennials and annuals in the urn, dividing some of the low-growing sedums into pieces and tucking them in around the edges.

With an artful eye, Sam placed perennials and annuals into the urn, dividing some of the low-growing sedums into pieces and tucking them in around the edges.

As I mentioned, Sam bustled around our garden center benches picking up various perennials; Achillea, Coreopsis, Dianthus, daylilies, Sedum, Leucanthemum, Salvia, and more. He explained that some perennials like the daylilies make a wonderful show for a while but once they finish blooming, “I just pop them out and stick them in one of my perennial gardens and then next year, it will bloom in the garden and I still have my investment – just in a different place. Sometimes I even sink the pot and all in my urn and then switching out the plants is even easier.” In place of the plants he pulls out, he sticks in a new, fresh perennial or annual – whatever strikes his fancy at the time!

The end result

The beautiful container garden will grow over the next several weeks, becoming fuller and spilling over the edges.

What a great idea – recycling plants from a container garden to the perennial garden. This can be done with all the perennials in the container at the end of the season! Some of the smaller perennials like the Dianthus and the colorful ground-hugging Sedum ‘Angelina’ will provide color and texture all season long with their beautiful foliage and will easily overwinter in the urn.

For season-long bloom, Sam tucked in various annuals here and there; some colorful petunias, Verbena, Scaevola, Lantana, Euphorbia ‘Diamond Frost’ and others.

The whole effect was spectacular and will only become more amazing as time goes on. I can’t wait to see how it changes over the next few weeks!

I’ll keep you posted!

Until next time – Happy Gardening!

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Sunday, Mark Viette and I spent some time walking through the beautiful Viette gardens. Mark wanted to show me some insect damage that he and Andre had noticed on some of the trees and shrubs this spring.

Borer holes in the bark of Viburnum

Borer holes in the bark of Viburnum

The worst was the borer damage on witch hazel (Hamamelis) and Viburnum. Borers can be a problem for many trees and shrubs including dogwood, ash, birch, spruce, and rhododendron. The culprits are the larval stage of different types of beetles (and some clear wing moths) that tunnel through the bark and feed on the plant tissue underneath which essentially girdles the tree. They leave open wounds at the entry points but often go undetected until damage to the whole plant is noticed. This usually includes yellowing and wilting of leaves, loose bark on trees, and eventually wilting of whole branches and leaf drop. One witch hazel has completely died back as a result of a severe infestation of borers, although new growth is now coming up from the roots.

Seen these hanging around?

Seen these hanging around? These purple structures are Emerald Ash Borer traps which are being used to evaluate populations of the pest.

A very serious new pest in the U.S. is the Emerald Ash Borer. These exotic beetles from Asia were first reported in Michigan in 2002 and have since spread to 14 states. To date, they have killed millions of ash trees and, unless we can figure out how to stop them, they could potentially threaten all the ash trees in North America. Yikes – reminiscent of Dutch elm disease and chestnut blight!

Borers often attack trees and shrubs that are stressed due to poor growing conditions or poor nutrition. The best protection you can provide your trees and shrubs against borers and many other insects and diseases, is to keep them healthy by planting them correctly and keeping them well feed and watered throughout the growing season.

Here are some tips for controlling borers in your gardens.

The characteristic cupping of the terminal leaves indicate the presence of boxwood psyllids.

The characteristic cupping of the terminal leaves indicate the presence of boxwood psyllids. Nymphs are protected inside.

Next were the boxwood psyllids. These pests have caused damage to many of the boxwoods in the gardens. The evidence of their feeding is quite obvious although usually not particularly detrimental to the plant – the damage is mostly cosmetic. The nymph stage of this insect feeds by sucking sap from the terminal buds and young boxwood leaves as growth begins in the spring. This causes a cupping of the terminal leaves on the affected branches, encasing and protecting the young nymphs as they continue to feed. By late May or early June, these “little suckers” mature into adults which then lay eggs that will hatch the following spring. There is only one generation per year.

Psyllid populations can be reduced by pruning out the branch tips with cupped leaves before the nymphs mature to the adult stage. Bonide All Seasons Oil or insecticidal soaps can be effective controls but only if they are sprayed when boxwood growth first begins in the spring. Once the cupping of the leaves is observed, the nymphs are fairly well protected from sprays. If you experience infestations of boxwood psyllids each year, an application of Bonide Annual Tree & Shrub or Bayer Advanced 12 Month Tree & Shrub Protect & Feed will give systemic control of these pests on boxwood. Always read and follow the label directions.

Aphids have sucked the juices from these viburnum leaves causing them to be very distorted.

Aphids have attacked these viburnum leaves causing distortion and yellowing.

On to the aphids! I really dislike these nasty creatures – mostly because when you have aphids, you usually have loads of aphids all crawling on top of each other – ewwww.

Aphids are piercing/sucking insects like the psyllids. They suck the juices from a wide variety of plants causing wilting and distortions of leaves and stems. As they feed, they secrete a sticky honeydew which encourages the growth of sooty mold on stems and foliage.

There was aphid damage to the foliage of many of the viburnums in the gardens. Many of the leaves had become curled and deformed – not very attractive in the garden.

Sometimes aphids can be sprayed off your plants with a strong jet of water from the hose and this may be enough to get rid of them but for trees and shrubs sometimes more aggressive measures need to be taken!

Well there are my insect stories for the week!

Until next time – Happy Gardening!

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Viette Iris FieldI guess it’s fitting that I should be talking about iris after my discussion of tree peonies last week. In the succession of spring blooms, iris typically fall between tree peonies and herbaceous peonies.

Iris cristata - Crested Iris

Iris cristata is a dwarf iris that grows well in a shady woodland garden.

It was actually as I was wandering through my gardens snapping pics of my beautiful tree peonies that I realized iris time had come. Walking by one of my woodland gardens, I noticed that the dwarf crested iris (Iris cristata) had begun to bloom. I love these cute little iris! The flowers are so dainty and they only grow about 6″ tall making them a wonderful ground cover for a shady garden! Imagine an iris that prefers the shade!

We planted a few small pots of Iris cristata many years ago and now they have spread to create a colorful spring show in combination with the bright yellow flowers of the Chrysogonum virginianum (Green & Gold) that we also have planted in that garden.

Antique Iris Heritage

This antique iris shows the fuzzy beard in the center of the falls.

In the Viette gardens, the tall bearded iris are beginning to bloom in earnest now. For many gardeners, these “orchids of the perennial world” have come to symbolize spring as much as the beautiful peonies. The tall iris flower scapes add a graceful vertical effect to the garden and even after the blooms are gone, the stiff, sword like foliage remains attractive through the summer perpetuating this vertical effect in the garden.

Why are they called “bearded” iris? For a long time I thought that the “beards” of the iris were the petals that hang down but these are actually the “falls”. The beards are the fuzzy, caterpillar-like structures in the center of the falls. They can be the same color as the falls or a bright contrasting color. The “standards” are the three upright petals.

Tall Bearded Iris War Chief

Tall Bearded Iris War Chief is very showy in the garden.

Tall bearded iris come in a wide variety of beautiful colors. When I first started working at Viette’s, I thought these amazing flowers were the most beautiful I had ever seen. The delicate blooms are truly orchid-like and some of the color combinations are just spectacular. There are even some with variegated foliage.

And then there are the reblooming tall bearded iris. These are really neat because they not only bloom in the spring with the other bearded iris but they also bloom again in the fall. Very cool!

Reblooming Iris Lavender & White Plicata

The reblooming tall bearded iris bloom in the spring and again in the fall.

Iris grow best in full sun and well-drained soil. Never bury the rhizomes completely when you plant – leave the top exposed and do not cover them with mulch.

Over time, iris clumps become overgrown and don’t bloom well anymore or they stop blooming all together. These old clumps are also more prone to disease, insect damage, and root rot. This is one plant that really benefits from being divided on a regular basis – maybe every 3 or 4 years.

Dividing iris is really easy and definitely worth doing if your iris seem to be tired and not performing as well as they had been. Here are some tips.

Tall bearded iris and reblooming iris come in many different colors.

Tall bearded iris and reblooming iris come in many different colors.

Yesterday I spoke with a gardener whose iris bed had become overrun with wiregrass. Ugh! She was very discouraged and was toying with the idea of digging all the iris out (about 100 plants!). When I asked her how long the iris had been in the ground, she replied that they had been planted for about 8 or 9 years. “Perfect timing”, I said! “Dig them out in August and divide them. Once the iris are out, spray the bed with Roundup (according to the label directions) to kill the wiregrass (I warned her that it might take 2 applications). Amend the bed with Plant-tone, rock phosphate, and green sand according to the Viette recommended rate, till it up, and replant.” It will be a lot of work but she’ll be killing 2 birds with one stone – rejuvenating her iris bed and getting rid or her wiregrass problem without risk to her iris.

We did this to our entire iris display bed at the nursery last August. They are blooming nicely this spring but next spring the blooms will be spectacular.

Until next time – Happy Gardening!

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Beautiful crepe paper-like blooms

I like peonies – mostly.

They have incredibly beautiful blooms that really brighten up the spring garden. Andre calls them the “aristocrat” of the perennial garden – the grand monarch of the spring.

Red tree peony

Here's our newest addition that is blooming for the first time this year!

My problem with herbaceous peonies is that after a rain, these big showy blooms are often left lying on the ground, bent over from the weight of the water-laden flowers. Most of the time they bounce back up but sometimes, especially after a particularly heavy rain, they just never seem to recover. It’s worse for the peonies with the big double blooms than for the ones with single flowers especially if they aren’t growing in full sun; they need full sun to develop nice thick strong stems that will hold the weight of the flowers better.

My solution to this problem has been to forget about planting herbaceous peonies (peonies that die back to the ground every year) and instead, plant beautiful tree peonies!

What is a tree peony?

Tree peonies (Paeonia suffruticosa) are the national flower ofChina. Unlike the typical herbaceous peonies, tree peonies are deciduous, woody plants that don’t die back to the ground in the winter – they just grow larger and more beautiful each year. Tree peonies aren’t really trees; they are really more shrub-like. They are extremely long-lived and in the right location, can live for well over 100 years!

A beautiful bicolor tree peony.

A beautiful bicolor tree peony, 'Shimanishiki'. This one is striking in the garden!

Unbelievable Blooms!

The beautiful, showy flowers of tree peonies have a silky, crape paper-like texture and are usually larger than the flowers of herbaceous peonies, measuring from 5″ to 10″ across. They can be found in a wide variety of colors and many even have a lovely fragrance. Single, semi-double, or double blooms cover this shrub peony beginning as early as the beginning of May, several weeks earlier than the herbaceous peonies, and because the branches are woody, tree peonies do not usually fall over from the weight of the flowers.

Growing tree peonies

Beautiful white tree peony.

My beautiful white tree peony, 'Godaishu', has been in the ground for about 9 years and is over 5 feet tall.

Tree peonies can grow anywhere from 4 to 7 feet tall and are an excellent background plant for perennial beds where they can provide a stunning focal point in the garden. The flowers are sensational in the spring and the foliage remains attractive throughout the season.

Since these are very long-lived plants, be sure to provide them with a well-prepared planting hole. They grow best in rich, loamy, well-drained soil that is high in organic matter. Plant them in sun to part shade however, dappled afternoon shade will protect the flowers from the hot afternoon sun and prolong the bloom. Once established, tree peonies are very drought tolerant. They are hardy to Zone 4.

A word of warning!

Tree peonies should never be cut back to the ground like you do with herbaceous peonies. They can be pruned lightly after the blossoms fade in the early summer. Any dead wood should be removed in the early spring when the buds begin to swell. A small amount of corrective pruning/shaping can be done in the early spring as well.

Until next time – Happy Spring Gardening!

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