Make a state­ment in your gar­den with lovely pot­ted trees

The Sacramento Bee - - Home & Garden - Y ADRIAN HIG­GINS

The house­plants are back in­side, the pots of an­nu­als have been emp­tied and the con­tain­ers won’t be re­planted un­til the spring.

But in this rush to lay bare the win­ter gar­den, we may be miss­ing an enor­mous op­por­tu­nity. Any gar­den, big or small, can be trans­formed by the pres­ence of a hardy tree grown in a planter out­doors year-round.

The most ob­vi­ous value of such a fea­ture is that you get a plant of ar­chi­tec­tural stature where you don’t have soil. A tree in a planter can act as a fo­cal point to the pa­tio or any gar­den space viewed from a room in the home. Two or three of them can an­nounce your en­trance, sep­a­rate the drive­way or pro­vide in­stant screen­ing on an ex­posed ter­race. In greater num­bers, they can turn a hot and un­wel­com­ing area into a leafy grove.

But there is a sim­pler rea­son for want­ing to do this.

“A win­terberry right out your back door you could look at ev­ery morn­ing, that’s pretty spec­tac­u­lar,” said Wendy Gen­try, a se­nior hor­ti­cul­tur­ist at Long­wood Gar­dens, in Ken­nett Square, Penn­syl­va­nia.

It prob­a­bly needs to be a small tree, or a sculptural shrub or conifer. The con­tainer should be large and frost-tol­er­ant – no frag­ile terra cotta. And let’s say right away that grow­ing trees in con­tain­ers can be pricey, though it doesn’t need to be, and is more de­mand­ing than a tree put in the ground. But the re­sults can be fab­u­lous, with an added bonus: Un­like other in­vest­ments in the gar­den, you can take it with you when you move.

It is use­ful to think of a tree in a con­tainer as a yin-yang pair­ing: The plant and its home should be matched in size (al­low­ing room for a few inches of root spread), in pro­por­tion and in char­ac­ter. The plant is the dom­i­nant part­ner, so the con­tainer should not jar in color or form. This isn’t to say it can’t be stylish.

One of the most con­vinc­ing pair­ings I have seen is at East­woods Nurs­eries in Wash­ing­ton, Vir­ginia, where owner Henry East­wood plants va­ri­eties of Ja­panese maples into hand­made planters of white oak. They are square and shal­low – just 8 inches deep – and an­gled out­ward to pro­duce a tray­like pro­file redo­lent of a bon­sai dis­play. East­wood makes the planters in his work­shop.

I won­dered whether the shal­low­ness of the planters would be a prob­lem for fu­ture root growth, but East­wood, who sells 100 va­ri­eties of Ja­panese maples, said the maple’s root pat­terns are much broader than deep.

“The 45-de­gree an­gle is com­pat­i­ble with what the roots do nat­u­rally,” he said. How­ever, the ef­fect of putting the trees in such a planter be­stows de­sir­able bon­sai-like qual­i­ties on them: They are stunted and take on an aged char­ac­ter early. You can also re­move the tree from the planter ev­ery other year and trim the roots a cou­ple of inches to pre­vent the tree from be­com­ing pot-bound and to pro­mote new root growth, East­wood said.

Given its own pedestal, a nur­tured maple would, af­ter 10 years, be­come “an in­cred­i­ble spec­i­men,” he said.

If you want more heft in your planter tree, con­sider the work of pro­fes­sional gar­dener Nick McCul­lough, of New Al­bany, Ohio, who in­stalled full­size Ja­panese maples for a client 11 years ago, and they are still go­ing strong.

He se­lected two up­right maples – pur­ple-leafed Blood­good and green­leafed Seiryu – and the clas­sic mounded green Viridis, and placed them in large, ex­trav­a­gant oaken con­tain­ers. The planters are 42 inches across and 4 feet tall. They are mark key points of en­try to the ter­races around the house and the tallest, the Blood­goods, are 12 feet above the pot to cre­ate a real pres­ence.

Prov­ing that even full­size shade trees will take this treat­ment, Long­wood’s Gen­try grows the red maple va­ri­ety Franksred in large dec­o­ra­tive teak con­tain­ers – Ver­sailles planters – that are 48 inches square and 36 inches high. The trees grow in stain­less steel sleeves within the boxes.

The planters are just one of sev­eral vi­tal el­e­ments to con­sider when cul­ti­vat­ing trees this way, along with the soil mix, the se­lec­tion of va­ri­eties, and wa­ter­ing and feed­ing.


Ja­panese maples (Acer pal­ma­tum and A. japon­icum) make good can­di­dates for con­tain­ers be­cause they are rel­a­tively small, grow slowly and have fi­brous roots.

De­vel­oped over cen­turies in Ja­pan, these maples come in many grow­ing habits, leaf shapes and col­ors. I am par­tial to up­right green-leafed ver­sions (ei­ther sin­gle trunk or multi-stemmed) over the pop­u­lar pur­ple-leafed va­ri­eties be­cause I find them vis­ually lighter and more tex­tu­ral, and they tend to have spec­tac­u­lar au­tumn col­oration. All types – up­right, spread­ing and weep­ing – work in the planters, East­wood said. What­ever va­ri­ety you pick, deft for­ma­tive prun­ing would en­hance the ef­fect.

But other de­cid­u­ous shrubs and trees are ex­cel­lent, too, es­pe­cially smaller or more com­pact cul­ti­vars.

Trees in planters have roots ex­posed to air tem­per­a­tures and be­have as if they are in colder cli­mates, so you will need to make sure your cho­sen va­ri­ety is tough enough. You should shift to at least one plant-har­di­ness zone


colder. For ex­am­ple, the Wash­ing­ton, D.C. area is in Zone 7, so you will need va­ri­eties that are hardy to Zone 6 or lower.

What to avoid? Be care­ful with box­wood; you may be bring­ing in box­wood blight that will spread to any ex­ist­ing box­wood in the yard. But if you have a box­wood in the gar­den that needs mov­ing, it would trans­fer hap­pily to a planter. Gen­er­ally, how­ever, broadleaf ever­greens such as hol­lies, camel­lias and rhodo­den­drons don’t make ideal planter spec­i­mens be­cause of win­ter wilt­ing and leaf burn.


Con­tain­ers must have three spe­cific qual­i­ties. First, they need to be large enough to al­low suf­fi­cient root devel­op­ment rel­a­tive to the top growth and to an­chor the tree when the wind blows. Even the small­est trees (ex­cept per­haps the small­est dwarf conifers) should have pots of at least 20 inches across. You can un­der­size the pot if you com­pen­sate with dili­gent wa­ter­ing and feed­ing, but gen­er­ally, the larger the pot, the bet­ter, be­cause size will min­i­mize the stress of fluc­tu­at­ing soil tem­per­a­tures and mois­ture.

Se­cond, planters need to be frost-proof and re­sis­tant to UV dam­age. Wooden, fiber­glass, cast con­crete and high-grade plas­tic are de­sir­able. Metal may get too hot in sum­mer and too cold in win­ter. Most (but not all) terra cotta pots are prone to crack­ing in win­ter.

Third, the planters must drain freely. Most trees will die in water­logged con­di­tions. A sin­gle drainage hole may not be enough, and planters on hard paving should be el­e­vated an inch or so for ef­fec­tive drainage.

Other con­sid­er­a­tions: Tall con­tain­ers drain bet­ter than shal­low ones. The planters should be lined with fil­ter fab­ric or some other por­ous cloth to pre­vent soil from wash­ing out and roots from grow­ing through and be­yond the drainage holes. If the top of the planter is nar­rower than the sides, root growth will make it dif­fi­cult to re­pot or root-prune the tree.


Do not use top­soil or any­thing not de­signed for con­tainer use. Even pot­ting mixes should be amended with sharp sand or, bet­ter yet, chicken grit be­cause peat moss, wood and bark mulch, and other or­ganic in­gre­di­ents even­tu­ally break down to a heavy soil con­sis­tency, im­ped­ing root aer­a­tion. The soil can be fresh­ened if you de­cide to root-prune, which can be done by slic­ing roots where they abut the planter sides.


Woody plants in con­tain­ers will need wa­ter­ing more of­ten than those in the ground, as much as twice a week or more in high sum­mer. Wa­ter un­til the planter drains. Don’t rely on rain to do the job, even in a wet year. You also need to wa­ter from Oc­to­ber to April to pre­vent the roots from des­ic­cat­ing. Wa­ter ev­ery two or three weeks in the off­sea­son but only when tem­per­a­tures are above freez­ing.


Trees in planters need to be fed reg­u­larly, but not ex­ces­sively. In­cor­po­rate a slow-re­lease fer­til­izer at plant­ing time. Or­ganic op­tions are avail­able, in­clud­ing dried kelp meal. Stop feed­ing for the year in Au­gust to al­low the tree to pre­pare for dor­mancy.


A sim­ple mulch of pine fines, river stones or pea gravel will help to re­tain soil mois­ture and thwart weeds. Some gar­den­ers plant flow­er­ing an­nu­als or peren­ni­als be­neath the tree, but that may be gild­ing the lily. De­mure, fine­tex­tured ground cov­ers or even moss would be a more ele­gant ap­proach.


Hor­ti­cul­tur­ist Nick McCul­lough used 42-inch-wide oak planters for a client's Ja­panese maples: a pair of the up­right pur­ple-leaf va­ri­ety Blood­good.


Planters can de­fine key edges of the gar­den. Here, de­signer Nick McCul­lough has used the up­right Ja­panese maple Seiryu.

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