Planning a Tropical Garden
in Colder Climates

I was privileged to attend a very informative lecture on this topic at Hicks Nursery, Westbury, NY in March 2012 .  The presenter was very helpful since we all had questions about over-wintering tropical plants rather than replacing them every year.

First, we walked through some of the common northern zone perennials that will compliment a tropical-look garden.  Of these, Hosta has many exotic and colorful varieties to add spice to shady spots.  Heuchera (coral bells), Echinacea Purpurea (purple cone flower), Rudabeckia (black-eyed Susan), grasses, ferns and clump-forming bamboo will set the stage for a Tropical garden in the Northeast, Midwest or Northwest regions.

Next, consider using tender bulbs that can generally be planted around Mother's Day.  These include Caladium, Elephant Ears, Cannas, Dahlia, Lily and Tuberose Begonias.  Their only requirements are that the soil be over 55ºF and that you place them in the appropriate place, either sun, shade, part shade.  They will do best if acclimated to the sunny areas slowly and can even be started indoors.

Of course, we all want to see the blooms of true tropicals, such as Mandeville, Bougainvillea, Bromeliads, and Orchids, Citrus or banana trees.  These do very well in heat of northern summers and can be over wintered if given enough air circulation when brought indoors.  I keep two banana trees in my basement each winter.  They are brought in, not watered for the entire winter, and simply left alone in the dark of my cellar.  When the temperatures are right, I carry them upstairs and replant in the garden.  So far, they are flourishing. 

The broad-leaf plants look very tropical, so I would use more of these and scatter blooming plants throughout the garden.  Now, whereas most of the vines and trees prefer full sun, orchids will do best in morning or late afternoon sun, as they will get in the branches of trees.  They are epiphytes, meaning they are "air plants" rather than being rooted in soil.  In their native environment, they live in trees.  Bromeliads are also air plants, often found growing in the limbs and crotches of trees.

But did you know you can put your houseplants outside for the summer?  Sure, your houseplants can go to summer camp in the yard.  Plants like Croton, Palms, Dieffenbachia, Dracaena and Coleus add amazing color from their leaf color and pattern.  By fall, they will be thick and lush.  Fertilize with 5-10-5 fertilizer during the growing season.

Over-wintering Tropical Garden Plants:

• Bring houseplants back indoors when the first frost is expected.

• Hardy tropical-looking perennials do not need any special care.

• Tender bulbs must be lifted and stored, although different species have different needs as to storage:  Dahlia can be dug and stored when frost knocks the plant back.  It does best if stored in humid conditions, in peat moss. There are Dahlias that can over winter in the garden (Dinner plate Dahlias) with mulch protection.  Lilies will bloom according to depth planted, so to extend the blooming season, plant these lilies at different depths.  They can be cleaned off, dried and stored in frost-free dark place.  Elephant Ears must have soil gently washed off, and allow bulbs to dry a few days before storing in basement (in dark).  They will develop rot if touching each other or are still damp when stored.

• It is okay to cut off foliage when bringing in bulbs while they are still green and growing.  This is what nature does when a frost hits.

• To remove banana trees in fall, use a spading fork and make a circle one foot from the stem to loosen it.  Bananas have a shallow root system and will pop out of the soil easily when loosened in fall.  Cut off the leaves after the frost, wash off any soil to prevent bringing pests from the garden into the house, put in into a plastic bag and let it dry out in the basement.

• A tip for growing Elephant Ears: use black pots because they heat up faster.  At end of season, store in a dry place, removing the fibrous roots, place in a cardboard box, not touching each other or put dry newspaper between the bulbs.

How to get the most out of a Tropical Garden:

• Accessorize with benches, statues, fountains, hammocks, birdbaths and other ornaments.

• Use night lights, spotlights or underwater lighting in the garden.

• In the pond, plant night-blooming lilies for added fragrance and interest.

• Use container plantings and flower boxes in seating areas.

• Build "trails" through the garden.

-- by Carolyn Weise

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