GROUP IV - Challenging,
Difficult to Grow
Special Condition Key:
| A | prefers more acidic soil; try 1 Tablespoon white vinegar in 1 gal. water monthly |
| B | brown leaf tips indicate salt burn/salt build-up |
| C | subject to iron or manganese chlorosis (best iron source is Kerex®) |
| D | subject to random branch die-back (which may be due to wrong-timed pruning) |
| E | when established, you can give less water |
| F | frost-sensitive, so protect if a hard freeze is expected |
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I |
more adaptable for use as an indoor bonsai than other plants, but still requires a certain level of temperature, light and humidity in order to be healthy and to thrive |
| L | may drop some leaves when relocated or repotted |
| M | very attractive to spider mites, so hose-spray and keep in very good air-flow |
| P | pinch first set of leaves when opened, the next will be smaller in size |
| R | do not root prune if at all possible; never bare root this kind of plant |
| S | leaves sunburn/windburn easily, so provide shelter/protection |
| U | larger specimens can take full sun most of day here when established |
| W | bark is tender or branches are brittle, so wire carefully, if at all, to avoid scars and damage |
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evergreen |
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deciduous/semi-deciduous |
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can bloom as bonsai |
| Note: Plants labeled as susceptible to chlorosis when grown in the ground should not have this problem in a container with a quality soil mix and regular fertilizer schedule. “Established” plants are firmly rooted and producing a good growth of new buds which have opened up into leaves. |
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GROUP IV - Challenging,
Difficult to Grow
This Page Last Updated: March 18, 2006
| Japanese Maple | (Acer palmatum) | A,B,S,W %* |
| some leaf burn is inevitable by mid-June; partially defoliate by cutting off a leaf and leaving only the bottom 1/4" of the petiole after most leaves have turned brown in mid-summer; do not defoliate two years in a row; leaves are more easily burned if the roots are too dry; don't ever clip healthy (non-burnt) leaves on young/thin-trunked trees or those re-potted this same year or any of the exotic cultivars; don't healthy leaf-clip even larger trunked trees after mid-June or thereabouts; use low Nitrogen fertilizer, especially after mid-summer; don’t keep soil too wet; needs some winter dormancy; don’t prune heavily after January or so when sap starts to flow too easily; repot every other year; consistency in soil quality and moisture level is said to be more important than protection from sun/wind; 'atropurpureum' variety is hardiest here; there are hardier maple species; see also Mountain Maples for info [Aceraceae; Sapindales] |
| Manzanita | (Arcotostaphylos sp.) | R ^* |
| usually difficult to grow in a container; treat like a cactus: very quick draining soil mix, little water, no fertilizer; buds back on old wood; successfully collecting from the wild said to be next to impossible; some varieties of A. uva ursa (kannicknik) said to be hardiest; per Oracle, AZ grower (2002), dig two weeks after a rain, add mycorrhiza to the soil, use rainwater (!), put moss on soil surface to help maintain moisture level, and spray with water until extra runs out bottom drainage holes [Ericaceae; Ericales] |
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Fairy Duster / Dwarf Powder Puff |
(Calliandra eriophylla) | E,F,U,W %* |
| said to bloom about three weeks after giving a high Phosphorus (middle number) fertilizer [Leguminosae; Fabales] |
| Blue Atlas Cedar | (Cedrus altantica 'Glauca') | ^ |
| Phoenix climate may be too warm; if you need to pull needles, focus on removal of the previous year's growth -- try to leave this year's growth intact on branch. [Cupressaceae; Coniferales] |
| Hinoki Cypress | (Chamaecyparis obtusa) | ^ |
| Phoenix climate may be too warm; use Reverse Osmosis (R.O.) water only; shaded inner growth has tendency to die; old growth can turn yellow then brown in winter [Cupressaceae; Coniferales] |
| Cotoneaster | (Cotoneaster spp.) | A,E,R,U % |
| low horizontal kinds do poorly in the desert heat; give lots of light [Rosaceae; Rosales] |
| Jade Plant | (Crassula arborescens) | F ^ |
| not as hardy as Elephant’s Food ; this plant has fewer and larger leaf pads and can die very quickly; DO NOT mist the leaf pads; fetilize less often in the summer than you do with other plants; overwatering causes loss of leaves and root rot; do not water for two weeks after transplanting/repotting; C. sarcocaulis said to have smaller leaves, but has "the scent of cat pee while it flowers" [Crassulaceae; Rosales] |
| Eucalyptus / Gum Tree | (Eucalyptus sp.) | D,F,R,W ^ |
| difficult to shape with either wiring or drastic pruning; easily rootbound; neglected nursery stock may be best as these specimens are often ready to be root-pruned and repotted straight away, and their condition might simulate dormancy; tend to experience dormancy in late-summer, as this is often the driest time of year, during this time, there will be no new growth at the tips of branches, and all leaves will have hardened off; it is recommended to remove all foliage from a specimen which is to be repotted; keep uniformly moist and do not let rootball dry out; commonly believed that these should never be repotted deeper than the previous soil level, for fear of the certain death of the tree; generally grow quickly from seed; one or more as yet-unidentified / untried species may do well here; some recommended species are E. camaldulensis (River Red Gum), E. maculata (Spotted Gum), E. meliodora (Yellow Box), E. nicholii (Willow Leaf Peppermint), E. saligna (Sydney Blue Gum), E. sideroxylon (Pink Flowering Ironbark), and the closely-related Angophora costata (Smooth Barked Apple); see also this thread. [Myrtaceae; Myrtales] |
| English Ivy | (Hedera helix) | ^ |
| give some sun, but mostly cool shade; needs good draining soil; cuttings take poorly; does not like to be wired except when shoots are young (to prevent cracking); large branches need to be wrapped in raffia or strips of Bounty® paper towels before wiring; tends to develop good nebari (exposed surface roots) with minimal effort [Araliaceae; Apiales] |
| Australian Tea Tree | (Leptospermum scoparium) | A,C,R,W ^* |
| DO NOT EVER LET THIS PLANT GO DRY, it does not wilt but dies in a matter of hours; water when soil slightly dry on top; style (repotting - pruning - wiring) in stages, not all at once; needs lots of light; don't prune back to bare wood as it rarely buds back on old wood; try not to bother the roots at all, avoid root pruning as long as possible, do NOT attempt to untangle roots, when root pruning is absolutely necessary shave off a thin slice from the bottom of the rootball and then repot, repeat annually or just continually repot in a larger container; might try sitting pot in dish filled with distilled/Reverse Osmosis (R.O.) water changed regularly, however also said to be subject to root rot; use MirAcid® infrequently and very diluted; less-readily-but-white-flowering L. humifusum said to be much better choice; Australian enthusiasts use some species as very hardy bonsai: what are we doing wrong on this side of the Equator? [Myrtaceae; Myrtales] |
| Blue Spruce | (Picea pungens) | ^ |
| keep roots cool, but not really wet; needs light and humidity; but NO full sun; Phoenix altitude may be too low; prune roots in January [Pinaceae; Coniferales] |
| Mugho Pine | (Pinus mugo) | B,M,R ^ |
| see other pines above ; Phoenix climate may be too warm; the variety called "mini-Mugo" is said to be even more difficult to grow [Pinaceae; Coniferales] |
| Japanese White or Five-Needle Pine | (Pinus parviflora) | B,M,R ^ |
| see other pines above ; Phoenix climate may be too warm; must have period of freezing each winter in order to remain in good health; if you need to pull needles, focus on removal of the previous year's growth -- try to leave this year's growth intact on branch; do not completely decandle in the spring as this will weaken the plant, cause branch die-back and possibly kill the tree later in the year -- always leave at least one or two buds on each branch; on branches that need more foliar density, remove some of the weakest buds; on branches that need less foliar density, remove some of the strongest buds; to fill a void in the foliage canopy, allow the candle to elongate and grow without restriction; to maintain compact form, pinch back 1/2 to 3/4 of the emerging candle; on branches with too much foliar density and several emerging candles, remove one or two; do not overwater, especially in spring and summer -- allow soil to ALMOST dry out in between waterings, then thoroughly rewater [Pinaceae; Coniferales] |
| Italian Stone Pine | (Pinus pinea) | B,M,R ^ |
| see other pines above ; yellow needle tips means soil too wet, but don’t let roots dry out; best bargains can be found right after Christmas, especially in the garden section of department stores (just be sure your choice was watered regularly) [Pinaceae; Coniferales] |
| Japanese Flowering Plum | (Prunus mume) | S %* |
| leaves burn easily; cut back on water if leaves have dropped; it is suggested to develop the top first with the plant overpotted, then reduce roots last; flowers between January and March; prune back leaving several buds after flowering to enhance the tree's design; do not prune the tree again until after the winter bloom; wiring should be done in the spring as required; a sustained feeding program will help the tree to tolerate summer heat and Sahara-like winds: shade and wind shielding during these periods will mitigate leaf damage; however, the tree can be completely defoliated in mid-to-late spring; do NOT use lime sulphur on; new growth lignifies quickly, so wire new growth soon after it emerges, and then monitor the wire on young growth because it will quickly scar; leaf spot fungus is most easily treated by simply pinching away the diseased leaves; to mitigate fungal problems, do not water the foliage on a daily basis; aggressively feed this tree until the design object is achieved by applying high Nitrogen fertilizers, such as a 20-20-20 NPK, and prune aggressively to promote ramification development, once this is achieved, back off on the aggressive or superfeeding to promote flower bud development; blooms on the prior year's wood, that is, the buds develop during the growing season of the year before. When pruning, do not remove all the flower buds; best time to modestly prune is just after the winter flowering; a little more info is here. [Rosaceae; Rosales] |
| Pyracantha / Firethorn | (Pyracantha sp.) | M,R,U ^* |
| surprisingly rated as a "4", does much better as a landscape plant here than containerized; repot with some of its original soil, best time possibly January here [Rosaceae; Rosales] |
| Azalea | (Rhododendron sp.) | A,C,D,S,W ^* |
| keep the roots cool, but not wet; with a fine, shallow, slow-growing root system, it's hard to water it correctly and the roots are subject to many diseases; when repotting, remove most of the very fine feeder roots -- these will always die after being disturbed by repotting, so they should be cut back short, they'll regrow quickly; for basic repotting, the wedge-cut method is recommended where each time you repot, a wedge of root is removed from toward the center in a different area so that after 4-5 repottings you have changed the entire root system; prefers a high organic soil content with peat moss and sand mix; amend soil mix with used coffee grounds to aid acidity; pinch the blossoms after flowering, and that is then the best time to repot this plant also; let a short stump remain when pruning branches; prune the top much less than the sides and bottom; older specimens said to respond well to heavy cutting by sprouting leaves on old wood if growth has been allowed to remain on the tips of the subject branch; let dry out a few days before wiring; do not use hard/tap water; may be so sensitive that if interior of pot is unglazed, toxic levels of lime may leach out to the roots; needs a little winter chill; these seem to do better if located in the cool shade “under the work table;” NO full sun; slight drop in soil pH to 6.0 may stimulate flowering; use commercial azalea/camellia mix plus some chicken grit; fertiliz with SuperbBoom® or MirAcid® at less than full label strength, but NOT during flowering or else the blossoms will quickly drop [Ericaceae; Ericales] |
| Wisteria | (Wisteria sp.) | C %* |
| the Japanese species has 15-19 leaflets, and likes full sun; the Chinese species has 7-13 leaflets, and needs some shade; both kinds prefer a high Phosphorus fertilizer in the autumn and also some fish emulsion or rape seed fertilizer; do not use Nitrogen fertilizer after September; have fast growing roots; stop all fertilizing when the flowering begins; cut off dead blooms right after flowering and repot at that time; prefer a deeper pot; trunk wood has to be at least ten years old before the plant will flower; blooms develop out of the previous year's growth; keep on the dry side in the winter; needs repeated wirings; a New Orleans grower (2001) is said to be successful with pure manure as a potting soil -- that's probably too "hot" for Phoenix -- but perhaps you can cut with at least three or four parts of chicken grit to make a workable mix for here; said that sitting in a dish of water in the summer will stimulate flowering; flower buds will drop if the roots are too dry. See also this. [Leguminosae; Fabales] |
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None of these plants is impossible
to grow as long-term bonsai here -- you may just need a little more learning
about the particular requirements. Try any of these for yourself
and increase our knowledge. Try unlisted species and varieties and increase
our knowledge.
The use of a greenhouse, especially during the summer months, can vastly improve your success with the less hardy specimens. However, be aware that "hothouse plants" are less able to withstand sudden, unforseen changes in growing conditions. These include outdoor weekend displays or shows, even Matsuri in late February. Just be advised that the risk is always there. |
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