The Q&A Archives: Tropical Plants for Zone 5

Question: Are there any hardy tropicals plants, like bananas, palms, etc, for here in zone 5?

Answer: Bananas may well be the ultimate symbol of the tropics. Growing Musa basjoo, the Japanese fiber banana and the new exciting Musa sikkimensis with its occasional red painting on the leaves is quite easy. Bananas require heavy watering and feeding. Full sun is optimum but they will grow in partial shade. Feeding with high nitrogen fertilizer?s with ratios like 21-7-14 and frequent heavy watering will produce a 6-10 foot leaf a week in the warm months. While it seems impossible to over water bananas they will not grow in bogs, good drainage is essential. Planting in windy locations will result in the island look as the thin leaves tear easily. Winter protection for a established banana in winters such as yours, you must wrap the trunks with a insulating material to keep from losing the height. If frozen to the ground, new growth will pop up in spring and grow about half the height as the original. If protected a grove of trunks to 15 feet with foliage reaching 18-20 feet will result from the extra effort. These impressive bananas bloom in about 4 years. A orange-purple flower about 5 inches in diameter will produce tiny bananas, most often they do not ripen.

Trachycarpus fortunei the Chinese windmill palm can grow to over 40 feet in zone 5. Many palms are hardy to the temperatures of zone 6 and 7 climates but few can handle the cold winter rain. Originating in the Himalayas from Nepal into the Sichuan region of China Trachycarpus fortunei will grow about a foot of trunk a year after it gets established. They are slow to establish though taking upwards of 2 years to really start taking off. Trachycarpus fortunei respond well to moderate summer watering. A fertilizer with high nitrogen and micro nutrients are helpful in the spring. Yellowing of the fronds are normal at the end of winter. Combining the use of Ironite and epsom salts (magnesium sulfate) at a ratio of 1 tablespoon per gallon of water helps to green up those yellow-green fronds.

The delicate Sino-Himalayan bamboos are very well adapted to the part sun areas in zones 5, 6,7, and 8; where they are easily combined with shade tolerant perennials such as: Cimicifuga, Darmara, Hostas, and Rodgersia. In their native environment they are the understory to the giant Rhododendrons. Possibly the most important criteria besides not drying out in the summer is: a significant difference between daytime and night time temperatures. A few examples include Fargesia nitida (blue fountain bamboo ) Fargesia darcocephala (Dragon Head bamboo) a relatively new clumping bamboo from the Sichuan region, Fargesia murielaea (umbrella bamboo) and Yushania anceps. Like the temperate clumping bamboo most of the large bold leafed Japanese bamboos prefer partial shade. With leaves up to 2 feet long and nearly 3 inches wide their effect is stunning. The smaller leafed Chinese bamboos are happiest in full sun. The effect of 40 plus feet and 3 plus inches in diameter is stunning. A lot of them have beautiful gold culms with random green stripes. Some popular ones would be Phyllostachys aurea (golden bamboo) P. aureosulcata (yellow groove) and some of its cultivars like the all gold form of aureocaulis, the gold with green stripes form of Spectabalis. The fastest to obtain impressive size is Phyllostachys vivax. Reaching easily 40 feet and 4 inches in diameter in 5-7 years. Care for bamboo can be nothing to nurturing. Regular lawn fertilizer several time in the spring and attempting to provide a minimum of 1 inch of water a week will provide good results. The running bamboos are fairly easily controlled with annual rhizome pruning done in the fall usually the first week of Oct. By going around the clump at the desired perimeter and working a spade with overlapping cuts all the rhizomes outside the area are cut and simply rot underground. Remember this technique must be done in the fall if the rhizomes are allowed to winter over they would be viable and severing them and leaving them underground would have negative results. The most beneficial part of using rhizome pruning as a method of control is the free exchange of water and nutrients underground which is stopped with vertical barriers.

If you have wet areas, gingers might be the answer. Hedychium coccineum and H. gardnerianum flower in summer and provide fragrant flowers. Probably the most tropical plant for wet places is Gunnera manicata and the smaller G. chilensis. With up to 10 feet wide primitive looking leaves and flowers these South American beauties need room. Petasites japonicus (fuki) with almost as large leaves is a good companion plant. Coming up as early as February in the form of a creamy-white flower spike, followed by the impressive leaves. Though not able to handle the summer heat Fuki fills in until the Gunnera comes into it?s own. A wet area bamboo is Phyllostachys heteroclada.

Warm drier planting could be filled in with some of the bold Phormium tenax cultivars such as Pink stripe, Gaurdsman, Maori chief. Add the arching Miscanthus sacchariflorus which can reach 15 feet in a growing season along with Miscanthus sinensis 'Cabaret' and 'Cosmopolitan' two highly variegated broad leafed grasses reaching 7 feet. The cannas from India such as Pretoria, Tropicana, Stutgart, Dark Knight not only provide bold leaves but outrages colored blooms. Eucalyptus gunnii and E. negelecta do very well in zone 6 and 7. Gunnii reaching 35 feet and the neglecta 12 feet with large blue leaves. In the last few year's we have been growing some new Eucalyptus that are doing quite well for us. They are E. pauciflora ssp. debeuzevillei and ssp. nyphophylla.

Best wishes with your tropical garden!

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