Weekly Column, Week of November 27, 2000 Prime Time Newspapers Calvin R. Finch, Ph.D., Director of Conservation, SAWS, and Horticulturist

PLANTING TENDER PLANTS

Our winters have been mild the last few years and we have begun to think that San Antonio is tropical. My plumeria stayed outside all winter in ‘99-2000 and did fine.

Every week on my radio show on KLUP 930 AM gardeners call with tales of avocado, citrus and even bougainvillea that they overwintered. Global warming may melt the ice caps over the next 100,000 years and we have been blessed with mild winters in San Antonio, but do not be lulled into thinking that we will never get cold weather again. Be ready, I think this year it will be cold!

For very cold-sensitive plants like plumeria and bougainvillea you could move them into shelter now. They do not like weather below 40 degrees F. and are not going to grow any more this year. The good thing about bougainvillea and plumeria is that they do not need light during the winter to survive. Just find a warm spot in a building or greenhouse and they will be fine until April. I cut back my bougainvillea and pile them up in the greenhouse. Some gardeners pull the plumeria trunks and stack them up like firewood until spring. I like to leave mine in the containers because it blooms more consistently and quicker once temperatures warm up; but, if you do leave the plumeria in a container, do not water it more than once per month. Plumeria are prone to rot if they are moist during the dormant period.

Oriental hibiscus will grow right up to the freeze that kills them, so make plans for protecting them now even though bloom is occurring. Unlike bougainvillea and plumeria, the tropical hibiscus require some light and water to survive the winter. Have a location in the greenhouse or near a sunny window to move them before the next freeze is forecast. Containerized citrus such as Mexican limes, satsuma oranges, and ponderosa or Meyer lemons are hardier than the hibiscus. If the container is small move them into the greenhouse. If the plants are large you will have to cover them if temperatures fall below 28 degrees F. A blanket(s) covered with a solid sheet of plastic or tarp works well. The blanket limits radiation cooling and the plastic resists cold wind and sleet. This method of covering also lends itself to heat sources if the temperatures fall below 24 or 25 degrees F. Put a mechanic’s light or some Christmas lights under the covering and the plants will be snug in all but the coldest weather. The blanket and plastic protection method requires that the covering be removed within a few days after the cold weather so the plant has access to light. It is also essential that the structure be removed or vented when the sun shines. Clear plastic structures heat up fast and fried plants will be the result.

Other plants in containers that benefit from protection from extremely cold weather are geraniums, blue daze, indigo, hydrangea, pentas and ixora. If you have the room for them in the greenhouse, they will look good and be ready for a fast start in the spring. If space is limited, find a location on the patio protected from cold winds and from drastic changes in sun intensity (cold shade followed by a hot blast as the day proceeds). Most days such tender plants will survive in such a location but, if real cold weather threatens, protect them with blankets and tarp.

To be ready for the likely cold weather and avoid the disappointment of dead, cold-sensitive plants, make your arrangements now before the “blue norther” descends on us.