Four Season Container Gardening - hardy plant

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ontainer gardening has made quite a resurgence these past twenty odd years. When I started my garden business in 1986, container garden- ing consisted of mostly annuals and tender perennials that were treated as annuals in summer pots. Of the hardy plants that were uti- lized, woody plants, mostly ever- greens, predominated. The excep- tions were troughs and bonsai, which were cultivated by only the most serious of gardeners. Potted houseplants and conservatory specimens were frequently sum- mered outdoors, but rarely inte- grated with annuals, other tender perennials, or hardy plants. Containers were usually heavy, expensive, or stylistically dated and rarely winter-hardy. Today’s incredible array of plant and container choices is stag- gering by comparison. Yet, I feel that most of us can do better on the finished product. So many con- tainer gardens, though lovely, are merely attractive collections or exuberant ‘salads’ in pots—lacking strong architectural elements and exhibiting little imagination or stamina. I’d like to challenge you to rethink some of your pot- ted gar- dens as year- round ornament, three-dimensional forms of strong line and color that are dynamic, exciting, and sure to satisfy your horticultural and artistic cravings. Let’s get started. First, select an area that you view on a daily basis. Potential areas are your entry, porch, or a view from your kitchen workstation, study, desk, or easy chair. Study the space and its dimensions. Look at the total height, width, and depth of the area. Consider the space as you would if you were entering a ‘defined space’ or a niche design in a flower show. Next, think about three con- tainers in a ‘three bears’ type of size relationship: large, medium, and small. I am emphasizing here a large pot that is a minimum of 24” wide by 20 “ high; a medium pot, minimum 20” wide by 18” high; and a small pot, 16” to 24” wide and 15” high. The containers may be identical in shape and color, or com- plementary. Since you are plan- ning for a four season effect, you will need to use containers that are winter-hardy. Containers created from wood, metal, fiberglass, resin, and some varieties of ceramic or composition concrete planters work best. Terracotta and most types of ceramic pots are poor choices, because they tend to crack or exfoliate due to ice and snow. (Note: High-fired and frost-resist- ant terracotta, such as those manu- factured in Italy (‘Impruneta’) and Crete and composition concrete or cast stone pots manufactured by Campania have fared extremely well over the past several winters for us in many of our clients’ Philadelphia area gardens.) The Hardy Plant Society Mid-Atlantic Group Feature Article March 2007 Vol. 21, No. 2 C 3 MID-ATLANTIC GROUP continued on page 4 Four Season Container Gardening by Michael Bowell

Transcript of Four Season Container Gardening - hardy plant

ontainer gardening hasmade quite a resurgencethese past twenty odd

years. When I started my gardenbusiness in 1986, container garden-ing consisted of mostly annualsand tender perennials that weretreated as annuals in summer pots.Of the hardy plants that were uti-lized, woody plants, mostly ever-greens, predominated. The excep-tions were troughs and bonsai,which were cultivated by only themost serious of gardeners. Pottedhouseplants and conservatoryspecimens were frequently sum-mered outdoors, but rarely inte-grated with annuals, other tenderperennials, or hardy plants.Containers were usually heavy,expensive, or stylistically datedand rarely winter-hardy.

Today’s incredible array ofplant and container choices is stag-gering by comparison. Yet, I feelthat most of us can do better onthe finished product. So many con-tainer gardens, though lovely, aremerely attractive collections orexuberant ‘salads’ in pots—lackingstrong architectural elements andexhibiting little imagination or

stamina.I’d like tochallengeyou torethinksome ofyour pot-ted gar-dens asyear-roundornament,three-dimensional forms of strongline and color that are dynamic,exciting, and sure to satisfy yourhorticultural and artistic cravings.

Let’s get started. First, select anarea that you view on a dailybasis. Potential areas are yourentry, porch, or a view from yourkitchen workstation, study, desk,or easy chair. Study the space andits dimensions. Look at the totalheight, width, and depth of thearea. Consider the space as youwould if you were entering a‘defined space’ or a niche designin a flower show.

Next, think about three con-tainers in a ‘three bears’ type ofsize relationship: large, medium,and small. I am emphasizing here

a large pot that is aminimum of 24”wide by 20 “ high;a medium pot,minimum 20”wide by 18” high;and a small pot,16” to 24” wideand 15” high. Thecontainers may beidentical in shapeand color, or com-

plementary. Since you are plan-ning for a four season effect, youwill need to use containers that arewinter-hardy. Containers createdfrom wood, metal, fiberglass, resin,and some varieties of ceramic orcomposition concrete planterswork best. Terracotta and mosttypes of ceramic pots are poorchoices, because they tend to crackor exfoliate due to ice and snow.(Note: High-fired and frost-resist-ant terracotta, such as those manu-factured in Italy (‘Impruneta’) andCrete and composition concrete orcast stone pots manufactured byCampania have fared extremelywell over the past several wintersfor us in many of our clients’Philadelphia area gardens.)

The Hardy Plant SocietyMid-Atlantic Group

Feature Article

March 2007 Vol. 21, No. 2

C

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MID-ATLANTIC GROUP

continued on page 4

FFoouurr SSeeaassoonn CCoonnttaaiinneerr GGaarrddeenniinngg by Michael Bowell

The key detail in over-winter-ing terracotta and cast stone pots isto keep them level. They should beset on pavers, slate, or other flatlevel surfaces,not in an areawhere snow andice tend to accu-mulate. If youhave a roof overthe containers,you may use col-orful ceramicpots. To ensurewinter survivalof the pots, youmay set plasticcontainers withinthe ceramic pots,planting directlyinto the plasticpots, making sure that both theplastic and ceramic containersdrain readily.

Drainage is KeyNow that your pots are in place,it’s time to ensure good drainagebefore you add soil. Many contain-ers, especially ceramic and terra-cotta types, have either nodrainage holes or insufficientdrainage holes. Be sure that thereare holes in the base of the contain-er; if there are none or if they areinsufficient, you can drill holes.Next, it is time to add drainagemedia to the basal 5-10% of thecontainer. If the containers areheavy, use lightweight media suchas overturned plastic pots or pack-ing styrofoam ‘peanuts’. (Be surenot to use the biodegradable type,which break down.) If you areconcerned about making yourlargest pots too heavy, you can cre-ate a false bottom by placing largeoverturned plastic pots in them totake up some of the volume, thenadding screening or weed fabric tokeep the soil from washing down.Placing feet under the pots alsohelps ensure drainage.

The potting media is the next

issue to consider. The type ofmedia you use depends somewhaton what you are planting and theoverall exposure. Soil mixes that

drain well areespeciallyimportant if thepots are fullyexposed to rain.Heavier mixesor an anchor ofgravel in thebottom with alight mix on topworks well forlightweight potsand potsexposed to dry-ing winds orsun. Heavymixes also work

for large trees, shrubs, and ever-greens, which can become top-heavy. I use primarily lightweightsoilless mixes and add weight tothe base of the pot if I am con-cerned about the pot toppling insummer thunderstorms or winterwinds. Many times I will recycleheavier soil from previously plant-ed containers into the bottoms ofmy newly planted pots, then add alayer of compost and top off withfresh mix. This keeps the top of thesoil weed-free and requires lessmaintenance. Compost also worksas a top dressing, but keep inmind that weed seeds will germi-nate in that top layer. Sheet mosshelps retain moisture around plantroots and prevents the soil fromwashing and splattering in heavyrains or from overenthusiasticwatering by less experienced gar-deners.

Fertilizer—for Containers a MustI add a slow release fertilizer to thesoil mix as I prepare it, and add abit more to the top after planting.Be mindful that most slow releasefertilizers are not active when thesoil temperature is cold (below60°F). On the other hand, those

same fertilizers release rapidlywhen soil temperatures exceed75°F and are readily leached away.So, a three- to four-month formula-tion will not work in cold springweather and may well last only sixto eight weeks in the heat of mid-summer. For most woody plants,this is not much of a problem, asthey do not require much fertiliza-tion in the cooler months. Coolseason, fast growing annuals andtender perennials, such as pansiesand fuchsias, will benefit from liq-uid fertilizer or a compost tea inthe cooler months, especially whenthey are young. The use of com-post in general helps buffer theextremes of chemical fertilizers.Honestly, I use some of every-thing. I find that if annuals orother young plants need a quickfix to get moving or if the trees orshrubs are a bit chlorotic or nitro-gen-starved, nothing beats fishemulsion or liquefied seaweed.And over the long run, good quali-ty soil with compost added is best.

Designing the ElementsOkay, now for the exciting

part. It is time to design with theplants. Although it may well nowbe shopping time for most of you,the real hard core among us proba-bly has a stash of plants alreadyawaiting a home.

To come up with a design andpot selection, you have alreadystudied the area in its entirety andconsidered the total cubic spaceyou would like to utilize. In anenclosed area, the parameters arealready set. In an open area, youmust consider the space in relationto the spaces around it. Visualizeyour containerized area as a unit.Think of it as a sculpture, asopposed to a painting. Its featuresshall be expressed in height,width, and depth. Place your con-tainers, starting with the tallest atthe rear left or rear right of center.Use the medium height pot in the

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center area and the shortest one inthe foreground. These containersare the basis for your four seasondesign. You can add contrasting orcomplementary pots or compo-nents (think holiday decorations,cut branches, glitter wands, pottedbulbs or summering houseplants)to create a dynamic scene overthe seasons.

Development of a colorscheme may be dictated somewhatby the surrounding area. Since thisis a four season design, I wouldstart with my evergreen selection.Do I go with yellow greens or bluegreens, cool colors or warm colors?Then I consider light and wind.Remember that the soil freezes inthe winter and broadleavedevergreens are easily dam-aged by drying winds andthe plants’ inability to absorbmoisture from the frozensoil. If the pots are placed inthe garden area, you mayuse broadleaved evergreensto better advantage plantedin the soil as part of yourcomposition. On a porch,you can coddle these samepotted evergreens withweekly doses of 50° to 60°water over the wintermonths. Most needle (pine,spruce, or yew) or scaly(juniper or chamaecyparis) ever-greens are much better adapted towinter pot culture thanbroadleaved evergreens, as theyare less likely to desiccate due tolack of available water.Complementary evergreensinclude Korean boxwood (manyforms, all extremely hardy) andthe ever colorful varied forms ofeuonymus. Antidessicants such asWiltpruf can help ensure survivalof the evergreens and also serve asa deer deterrent. (We have notedthat the broadleaf evergreens thatwe treat with antidessicants areless prone to deer munching thanthose untreated evergreens.)

Plant the tallest woody plantsor those with the most linear out-line in the largest container, eitherat rear or mid-depth. Add a con-trasting shape, more rounded, intothe next largest pot, again at therear or middle area. Use a trailingform with contrasting texture inthe lowest container and if spaceallows, repeat this same plant inone or more of the other pots.Contrasting evergreen form andcolor can be provided by the sameplant, such as yucca or aucuba.(Although aucuba, camellia, cryp-tomeria, and even leucothoe aresensitive to winter cold and desic-cation in containers, they servewell from March through

Decemberand canspend thebalance ofthe year inthe groundor in a pro-tected loca-tion.)Evergreenplants anddwarfconifers thathave had asuccessfultrack recordfor me

include sciadopitys, variegatedand dwarf pines, most forms andcolors of chamaecyparis, abies,ilex, and juniper. Deciduous plantsinclude blueberries (flowers, fruitand red winter stem color), azal-eas, hypericum, taxodium, dog-wood, holly, cotinus, and the manycolored foliage forms of sambucusand forsythia. A great floweringplant is Rosa ‘Peach Drift’, a newintroduction from Star Roses thatis incredibly disease-resistant andliterally flowers for seven months(two plus seasons).

Herbaceous perennials providethe next layer to your compositionand add a dynamic and reliable

element. Some of my favorites arehakonechloa, cimicifuga, begonia,lilies, rogersia, ligularia, trollius,Japanese anemone, Christmas fern,autumn fern, painted fern, andhosta for shade. All are long-livedand foolproof, as are daylilies,hardy salvias, sedums, asters, echi-nacea, artemesias, Siberian andJapanese iris, hardy hibiscus,lavenders, and dianthus for sunnylocations. Lysimachia nummularia‘Aurea’ performs well in shadeand sun if kept adequately moist.

Annuals and tender perenni-als are colorful and dynamicfillers. My absolute favorites arelantanas (their multihued flowersare perfect to tie surrounding col-ors together), cane begonias, cali-brachoa, dahlias, and impatiens.These all require minimal upkeepexcept for staking and deadhead-ing the dahlias, and combatingbudworm on the calibrachoas withan organic pesticide.

Summering houseplants (con-servatory plants) such as hibiscus,abutilon, bromeliads, brugmansia,palms, begonias, anthuriums,ferns, orchids, tillandsias, fuchsias,tibouchina, heliconias, citrus,crinum, gardenia, clivia, and aga-panthus all will do well out ofdoors for some months of the yearand can add instant drama to yourcontainerized garden display.

Pest control, other than bud-worms, is something I rarely do.Deer and rabbits are repelled bestwith Liquid Fence, though mostplants in containers have fewerproblems with these pesky herbi-vores due to their elevation andproximity to dwellings.

Long term maintenance ofyour containerized garden areainvolves mostly light feeding andseasonal thinning and pruning.Removing the top few inches ofsoil and replacing it with freshmedia will discourage weed seedgermination. Some plants may

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perform best if they are rotated onoccasion, either in their existingcontainers or into adjacent contain-ers. Some herbaceous plants willneed to be divided, so that theywill not upset the visual balance.Woody plants that do not respondwell to pruning, such as sprucesand pines, may outgrow their containers in a few years andrequire transplanting into the garden, where they can continueto develop.

Drainage holes should bechecked and reopened at leastannually. The best time is duringeither autumn cleaning or springplanting. Be especially mindful of any pots that have settled intothe soil. These are prime candi-dates for drainage issues that canlead to a rapid decline in planthealth—again, placing containerson a level hard surface, a bed ofgravel, or raisers (feet) will preventthis problem.

A Sample Four Season PlanterComposition for Medium ShadeIn March, plant three pots using afive-foot Chamaecyparis obtusa inthe largest pot and a Chamaecyparispisifera ‘Strathmore’ (gold mopcypress) in the foreground pot. Planta coral twig dogwood Cornussericea ‘Cardinal’ in the center pot.Add Euonymus fortunei ‘Moonshadow’to both front pots at the base of thegold mop cypress and dogwood,respectively. Plant one Yucca fila-mentosa ‘Color Guard’ in the largestpot and repeat it in the smallest.Add solid yellow pansies, red pan-sies, and golden variegated ivyHedera helix ‘Goldchild’ to all of thepots.

In April, about mid month, isthe time to add plants that can takeheavy frosts into the upper 20°s Fand provide temporary color. Addpots of budded ranunculus andholiday plants such as floweringbulbs and azaleas that are nowreadily available. Make sure to

plant tulips and narcissus a bitdeeper than they were in their orig-inal containers to help supportthem. You might also use somedeciduous branches for support.Remember that newly addedplants might require additionalmoisture, as their roots are not yetestablished into the entire soil mass.

In May, add a fourth pot—yourorange Clivia miniata that youbrought outdoors a month earlierand have kept in a shaded place toprevent sun scald. Chances are itwill repeat flowering in early sum-mer, since it has experienced coolnight temperatures. Replace spentbulbs with Hakonechloa macra‘Aureola’ to the medium and lowcontainers. Add late floweringorange tulips to the medium con-tainer. You shall replace these spenttulips later in the month with anupright growing Fuchsia x‘Gartenmeister Bonstedt’. A fifthlow trailing pot (easiest is a hangingbasket placed on the ground) maynow enhance your composition.

In mid-June, remove the dog-wood and plant it in the groundbehind the largest pot or in anotherarea of your garden. Add asalmon/coral cane-type begoniaBegonia coccinea to the pot vacatedby the dogwood and replace thewaning pansies with salmon andred impatiens. Add a chartreuseHosta ‘Sum and Substance’ to therear pot and an Acorus gramineus‘Variegatus’ to the front pot. Add asixth pot behind the others filledwith yellow variegated gingerAlpinia zerumbet ‘Variegata’. Thiscombination will look greatthrough the summer months. Of course, you can always add an orange flowering bromeliad,Guzmania ‘Orange Crush’, andsome tall candles for a mid-sum-mer party.

Keep your container plantingsgroomed by removing all deadfoliage, flowers, and stems to pre-vent disease. Some plants shall

need to be coached by removing orsimply adjusting some stems andfoliage to allow space for neighbor-ing plants to develop.

Prior to frost, remove the canebegonia and take to a sunny win-dow indoors. Put the potted gingerin a protected location.

After a light frost, move theclivia to a more protected location. After a heavy frost, cut out theimpatiens and remove the fuchsia.Plant Narcissus ‘Fortussimo’ bulbsin one of the pots and fill in emptyareas with pansies.

In December, cut some of thatcoral twig dogwood and add thosebranches to your pots with anassortment of cut greens andbranches of Ilex verticillata ‘WinterGold’, along with some gold andred glass balls, metal gazingglobes, or ‘Simple’s ReflectorWands’. Use an assortment ofupright, spreading, and cascadingcut greens to complement thebright and colorful euonymus andyuccas. Treating the cut greens,deciduous and berried branches,and potted plants with antidessi-cants, in addition to keeping mois-ture in the pots, will add longevity.You can easily replace the brown-ing branches of cut greens andholly over the winter months andadd a white flowering hellebore inlate winter as you conjure ideas forthe seasons ahead!

Michael Bowell is a gardener by vocation andavocation who has a keen interest in both hardyand tropical plants. He is a flower show judgeand an accredited American Orchid Societyjudge who has exhibited for twenty-five yearsin various flower shows. His company, ‘Createa Scene’ of Malvern, PA, creates and developsgardens for a select clientele and has recentlycombined forces with his partner, Simple, indesigning for horticultural trade shows.Michael also lectures frequently to orchid andplant societies on various aspects of design,exhibition, and horticulture. He resides with histhree schnauzers and assorted cats, reptiles,turkeys, chickens, peafowl, and ducks inCharlestown Twp. in Chester County, PA.