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Flowering Bushes for Planter Boxes

May 26, 2015

Written by The Tree Center.
Flowering Bushes For Planters

As spring turns into summer we all crave color. If you have a small garden and a deck or terrace for pots and tubs, or no garden at all and only planter boxes and pots to work with, the natural temptation is to rush out and buy annual flowers to fill those boxes. Every fall they have to be thrown out and every spring bought all over again. No wonder garden centers like to promote them – it adds up to a lot of money over a few years.

There are other choices and planting your boxes with shrubs that will flower all summer long, is a great alternative. Today there are many shrubs with long flowering seasons so there are lots of choices for permanent planting that will not only save money in the long term, but also give you bigger masses of plants that are ideal for larger areas or to make a bigger impact.

Of course you can also use shrubs as a ‘backbone’ for your containers and then still put annuals and bulbs around them for extra color.

Prepare your Planters

Planter Box DrainageIf you are going to put longer term plants in your planter boxes and pots, it is worth making sure they are suitable and properly prepared. The most important thing is to have drainage holes. Without these your soil will turn sour and become waterlogged over time and your shrubs will suffer. If you have wooden or metal boxes it is easy to drill a few extra holes. Even clay containers can be drilled if you use a slow masonry drill or fill them with sand first.

Because you are putting these shrubs in for a while, you want as much soil as possible, so don’t waste time and space putting gravel in the bottom. Just cover the holes with a piece of old screening from a door or window screen to stop the soil running out. Many garden centers will have soil specially mixed for outdoor planters, with bark and coarser material added so it won’t shrink over the years. If you can’t find one of these, add some shredded bark to regular potting soil, maybe one part bark to five parts of soil. Fill the planters almost to the top as you put your shrubs in place, but leave at least an inch clear at the top so you can water thoroughly without the water flooding over the top.

Shabby Chic Planter Boxes

Planter boxes can be built-in to the design of your deck, or you can buy all kinds of containers to suit your décor. For a classic look, large square wooden boxes look spectacular filled with flowering shrubs, or big Italian terracotta pots always make a statement. Modern containers in fiberglass or metal will give a cool, hip look to any terrace or balcony and today there are some great choices in plastics that combine low cost with good design.

Some Ideas for Flowering Shrubs to Grow in Planter Boxes and Containers:

Crape Myrtles

Crape Myrtle Planter

Most people think of these plants as large shrubs and trees, but breeders have put a lot of effort into producing smaller forms that are ideal for planter boxes. Top pick is the Dazzle series, with Berry Dazzle Crape Myrtle in fuchsia-pink, Strawberry Dazzle Crape Myrtle in rose-pink and Cherry Dazzle Crape Myrtle in cherry-pink all growing no more than three feet tall and the same across. With their vibrant colors, long bloom period and drought tolerance these are the ideal choice for planters that bask in the sun all day long. If you live in cooler areas, the dwarf Pocomoke Crape Myrtle is rose-pink and one of the hardiest around. These fabulous plants will flower continuously until the frost and go out with a flourish of red and orange fall color in their leaves.


Hydrangeas

Hydrangea Planters

A shady deck is great during summer and there are shrubs that will brighten shady spots too. First choice has to go the Hydrangeas, with a long bloom season of huge and colorful flower heads on rounded shrubs. Very popular and hardy even in colder regions is the Nikko Blue Hydrangea. This spectacular beauty looks great in the shade with its cool-blue flowers really standing out. In planters it is easy to use the special fertilizers you will find to really keep that blue color at its best. As a great contrast, add Hydrangea Double Delights™ “Perfection” with its dense pink balls of color that lasts for months. Both of these plants will flower on the older stems early in summer and again on new shoots later, so you get continuous blooming all season long. If you live in colder regions we recommend the Sunday Fraise Hydrangea, which has conical flower heads in a beautiful dusky pink.


Roses

Roses in Planter

Everyone loves roses and new varieties are not only small enough to use in planters, they never stop flowering for the whole season. The best for planters have to be the Knockout Series, which are hardy into cold zones as well as heat-tolerant. The Double Knockout Rose will wow you with its deep pink blooms, or try the Double Pink Knockout Rose for a softer coloring. For a cool, sophisticated look the White Out Rose will fit the bill – blend it with Nikko Blue Hydrangea for a dynamic and elegant look. For extra height and room beneath for annuals or smaller shrubs, plant the Knockout Rose Tree, which has red double flowers, in the centre of your planter. The shrubby Knockout roses can also be planted below it for an ‘all rose’ look.


Butterfly Bush

Butterfly Bush

For low-maintenance and drought-resistance in flowering bushes for planters, the different Butterfly Bushes are a great choice. They will attract hosts of butterflies to your deck, delighting your children and yourself, and bring vibrant color too. Choose the Asian Moon Butterfly Bush for its soft blue, or the Pink Delight Butterfly Bush for its rosy shades, these arching plants will bring a different look to your deck. Prune hard in late winter to encourage a low, bushy habit suitable for planter boxes.


Caring for Potted Shrubs

The first essential is watering and plants in containers should be thoroughly watered, until water flows from the drain-holes, every time they are watered, but allowed to become a little dry on the surface between watering. Simple drip-irrigation systems can be set up for planters that will take a lot of the work out of caring for them, especially when you are away for a while.

Fertilizing is important for good results and liquid fertilizers are the easiest way to go. For organic growing use fish emulsion or other liquid products, or just use any suitable liquid fertilizer for shrubs or roses. Follow the directions for using the type you buy. The newer slow-release granular fertilizers are also great – one application in spring is all that is needed to keep your plants happy all summer long.

Unless your shrubs have decorative seed-pods, remove the flower-heads as soon as they fade. This will encourage more flowers to develop – leaving seeds to grow reduces flower production. At the end of winter remove weak twiggy branches and trim the strong ones back a little to encourage denser growth from your bushes. At the same time add a little fresh earth to the pot – it will probably have shrunk a little anyway and will benefit from topping up.

 

A Last Word

Flowering shrubs as a replacement or addition to annual flowers in planters are a great idea that will save you money and make a strong visual impact and a great change from those old annuals you have been planting for years. Less work and more color – what’s not to like?