Have you bought foliage house plants that soon dropped their leaves? Many people have; in fact, that was par a few years ago.

Now the time is near when most foliage plants sold to go into the home will be in tiptop condition, able to survive and stay attractive indefinitely if given reasonable care.

It is a tremendous improvement over a few years ago, and a lot of the credit belongs to Dr. Charles A. Conover, director of the University of Florida Agricultural Research Center, at Apopka, and his staff.

A high percentage of foliage platns are grown in Florida, often in full sun. When taken into the home with its low-light intensity, they could not live very long.

With high-light intensity they produced small, thick, light-green foliage. When taken into the home with its rather dim light, the leaves could not function to produce food for the plant.

Now most of them are grown in the shade. Besides being darker, glossier and more attractive, the shade leaves contain more chlorophyll and efficient in the production of food under low-light conditions.

The aim, Conover said, was to be certain that every plant shipped from Florida would be acclimatized (adjusted) to grow satisfactorily in the home.

But that was only part of the problem. When the plants are shipped in trucks, enclosed in paper boxes, they may go five days without light.

"Cramming any living organism into a dark, crowded, airless, high humidity box and bounding it around for several days to a week on a truck might be expected to cause injury," said Conover. "This is how most plants are shipped.

"Despite this harsh treatment, all but about 5 percent are acceptable.

"Research has demonstrated that properly acclimatized plants not only provide greater consumer satisfaction, but also are easier to ship because they have lower respiration rates, require less moisture and tolerate darkness better. In addition, lowered nutritional levels provide desired quality under shade, lower the soluble salts level and reduce the osmotic potential -- thus decreasing leaf drop both in transit and under interior situations.

"Only disease-and-pest-free plants should be packaged and shipped because infection and pest problems only worsen in the box. Mite populations may explode.

"Foliage plants should be watered the day before packaging. Excessively wet soils may drain and damage boxes, and dry soils will greatly increase leaf drop.

"Leaves of foliage plants should also be dry at the time of packaging to reduce the spread of foliar diseases.

"If plants of poor quality are packaged and shipped, it may be the last time you have the opportunity to ship to that customer," Conover warned the growers.

"Shipping temperatures of 32 degrees f. or below will damage almost all foliage plants," said Conover. "It is usually characterized by blackened or collapsed foliage.

"Chilling injury can occur on many foliage plants if the air temperatures drop below 45 degrees f. for long periods or if air temperatures are between 35 and 40 degrees f. for relatively short periods.

"When boxes containing chilled plants are opened, they often exhibit no symptoms whatsoever, but will develop browned, watersoaked or blackened areas in tissue within two to five days.

"Thus, chilled plants may be accepted from the shipper without knowledge that they have been damaged in transit. Chilling injury increases in severity with time and although one day at 40 degrees f. may not damage most foliage plants, fairly severe damage can occur when plants are subjected to cool temperatures over a three-to-five-day transit time.

"High temperature injury is usually noticeable upon unpacking, as symptoms include dehydration and often yellowing.

"Recommendations for shipping based on research and experience indicate that 55 degrees f. is the lowest temperature that should be considered for shipping and even at this temperature it is possible that chilling injury may occur with some plants.

"Best shipping temperatures seem to be in the range of 60 to 65 degrees f. Temepratures as high as 75 degrees f. may be acceptable during the transit period, but research data is not complete at this time.

"Higher temperatures, though, increase ethylene levels.

"Air pollution can damage plants. Outside pollutants from industry or truck exhaust may enter through an improperly maintained temperature control unit or open doors.

"Pollutants produced within boxes are rare except for ethylene which can be generated as a natural plant emission or from damaged leaf, stem or root tissue.

"Ethylene is also produced by fruits and vegetables so these products should never be shipped in mixed loads with foliage plants.

"Shipping time also influences plant quality. The longer plants are held in darkness, the lower the level of stored carbohydrates and chlorophyll levels. These plants will be at a disadvantae after placement indoors.

"Plants should not be boxed until loading and shipping is imminent, and they should be removed from boxes as soon as received to maintain highest quality."