Norfolk Island pine likes cool, sunny room best

A Calais gardener asks for information on growing the Norfolk Island Pine (Araucaria excelsa) in the home.

This exotic from the southern hemisphere makes an excellent house plant that can live for many years indoors and attain a height of 5 feet or more. My mother kept one especially for use at Christmas time, when its graceful tiers of flattened branches displayed tiny white lights and delicate ornaments better than any fir or pine.

Norfolk pines prefer a cool greenhouse or sunroom to a warm, dimly lit interior room. If you don’t have such a space, a south-facing window in the coolest room in the house or apartment will have to do. Rotate the tree daily so that each side receives favorable light.

Annual repotting in a pot 1 inch bigger than the previous year’s is recommended up to the 8-inch pot stage. My garden encyclopedia recommends a mixture of two parts loam and one part leaf mold with a little sand sprinkled in. It also advises that one remove the loose soil on top of the pot once a year and replace it with fresh leaf mold or compost.

Norfolk pines produce new growth from March to September and during this period, they need a monthly feeding using a soluble plant food (Miracle Grow or equivalent) at normal strength (follow label directions).

In summer, one might find a protected spot out of doors to place a Norfolk pine. A little morning sun and plenty of afternoon shade would be best. Most house plants respond to this simple kindness with luxuriant and noticeably healthier growth.

An Orono reader would like to know a source of geranium seeds and any tips on starting them.

Most of the major seed houses carry geranium seeds. I’ll single out Stokes Seed Co. (P.O. Box 548, Buffalo, NY 14240) because of the excellent cultural instructions printed on the back of each seed packet. The bad news is that it is a little late to get started with seed geraniums for this year. In the greenhouse we sow this important crop any time from late December through the month of January for blooming plants in late May. A March 1 sowing would produce flowering plants possibly by the Fourth of July.

The same reader has an 8-by-12-foot greenhouse attached to the house and would like my recommendation for heating the same when using the space to start seedlings in late winter and spring. A small electric space heater has proven inadequate, as has leaving the door to the house open at night.

I do not recommend allowing much communication between the moist air of a working greenhouse (i.e. one that is full of actively growing plants) and the dry air of the home. The result will almost certainly be moisture migration into the insulation and other cool parts of the house. An attached greenhouse should have its own heat source as well as a convenient way to vent excess heat on sunny days.

A greenhouse of 100 square feet or so would require a heater that produces 10,000 to 20,000 Btu, depending on the type of glazing and how cold the outside temperature is. LP gas heaters are the most economical to install and operate in this size range. Ideally one should have a wall-mounted unit, vented to the outdoors and thermostatically operated. Consult your local gas company for costs and other technical information.

Heating a greenhouse is a little bit like trying to warm up the great outdoors. In our family’s business, we see the oil man every seven to 10 days all winter long, and he generally wears a satisfied smile as he comes rumbling down the driveway.

Michael Zuck of Bangor is a horticulturist and the NEWS garden columnist. Send inquiries to him at 2106 Essex St., Bangor, Maine 04401.