As we head into the short, cold days of the winter solstice is there any food that so evokes thoughts of warm and sunny climes as well as citrus does? As a species, citrus has been cultivated since 3000 BCE and may originated in the area of the Himalayas more than 5 million years ago. Grapefruit, lemons, limes, oranges, and tangerines are among the domesticated sweet-tart fruits of the genus Citrus that we know and love. Most of them are descended from Citrus medica, also known as citron, a large, fragrant citrus fruit. The lemon is a hybrid of citron and bitter orange (Citrus x aurantium), and the many varieties of limes are hybrids of citron, pomelo, mandarin orange and micrantha (a slow-growing, unpalatable species from tropical Asia).


From the top, a pomelo, navel orange, lime, clementine, grapefruit, and in the middle, a lemon.

The Ponderosa lemon, Citrus x pyriformis, is another hybrid of the citron, this time with a pomelo, Citrus maxima. An ever-bearing slow-growing tree with glossy leaves and large ovate fruit, it is often grown as an ornamental plant in Connecticut. Less cold-hardy than a regular lemon, can be grown outside from May to October but will need to be overwintered indoors. I acquired one of these this summer and enjoyed the lovely scent of the large, purple-tinged, blooms each time I passed by it. As of October, none of the many fruit had ripened although they were much larger than the average commercial lemon. I later learned that they can reach the size of grapefruit and that this can take up to nine months!


Ponderosa lemon tree outdoors.

Taking care of a Ponderosa lemon is easy. Keep it in a clay or other porous material container that has good drainage. Allow the top inch of soil to dry out between waterings and then give it just enough to moisten the soil without allowing it to become soggy. When the plant is outside during the warmer months it may require daily watering like other container plants. Back inside, it may benefit from being placed on, but not in, a shallow tray of pebbles and water to keep the humidity level up. A monthly dose of a liquid fertilizer while indoors will benefit it, twice monthly when it is actively growing outside. Ponderosa lemon plants may be grafted onto dwarf rootstocks to keep their size manageable. They may still need some pruning to shape them at any time of the year but keep an eye out for the abundant spines along their branches.


Spines on a Ponderosa lemon tree.

The Ponderosa lemon produces blossoms and fruit year-round. You may wonder how pollination may occur in a home environment where there aren’t any bees or other insects flying about. It is due to the fact that the flowers of the Ponderosa lemon are perfect flowers, containing both male and female reproductive parts within the same blossom. Out of doors the movement provided by a breeze is enough to transfer the pollen grains from the stamens to the stigma. In your home, simply brushing a hand lightly against the flowers can achieve the same result.

So, while the Ponderosa lemon fruit will not be ready for use for a few more months there are still many other varieties of citrus that are ready and willing to grace our holiday tables and treats. For most varieties of citrus, the harvest runs between November and April and possibly into May if the conditions are good. The satsuma, or mandarin, orange (Citrus reticulata) produces fruit from August until December and so it has always been a favorite treat for a Christmas stocking, since the 19th century. We made a Victorian-style ornament from dehydrated slices of oranges, lemons, and limes many years ago and it still graces our tree each year.

The Florida navel oranges, Citrus x sinensis, are at their best from November to January, the California navel from December to May. Using the rind of navel oranges to make candied orange peel is one of the hallmarks of the holiday season for me. Candied, or crystallized, orange peel may seem to be an old-fashioned confection but it is always a popular addition to any cookie tray at the end of a meal. Crystallizing fruit is an easy process of preservation whereby small pieces of fruit or rind are cooked in a simple sugar syrup. When I make candied orange peel for the holidays, I start with 4-5 large navel oranges that have been rinsed and dried. The first cuts remove the navel and stem ends of the fruit. Standing the fruit on one of these flat cuts, cut longitudinal slices of peel away from the inner white pith. These slices often need to be cut lengthwise again into 2 or 3 strips.


When all of the orange peel has been prepared in this way they are put into a saucepan and covered with cold water. Bring them to a boil and then simmer them for 15 minutes. Drain the peel. Repeat this process two more times. This helps to remove bitterness from the peel.

While the peel is draining for the final time, bring one cup of water and two cups of sugar to a boil in the saucepan. Add the drained peel and reduce the heat to a simmer. Allow the peel to simmer until it has become translucent, up to an hour. Transfer the peel to a piece of parchment paper and allow it to cool. Toss the pieces of candied peel in superfine or confectioner’s sugar and allow it to dry overnight.

Keep it in an airtight container and use it to garnish your holiday trays or simply enjoy a few pieces with a cup of tea as you relax in front of the fireplace.

Susan Pelton

UConn Home & Garden Education Center

Last Sunday was rather cold and raw so a friend and I decided to take a ride to Tower Hill Botanic Garden in West Boylston, MA to bask in the glorious scents and sights of the Garden’s two citrus conservatories, the ‘Orangerie’ and the ‘Limonaia’. A few hundred of years ago, wealthy aristocratic Europeans developed a hankering for sweet oranges, tart lemons and other semi-tropical citrus fruits that shipped poorly from newly discovered foreign lands.

Orange tree at Tower Hill Botanic GArden

Their estate gardeners were charged with raising these much desired fruits and tried overwintering the large potted plants in sheds and other sheltered places. Eventually three-sided enclosures with a glass wall were developed so plants could receive some light all winter long. As the industrial revolution progress, steel framed greenhouses became available for such exotic fare.   

Limonaia at Tower Hill

 The conservatories at Tower Hill follow along a more classical, eighteenth century style of greenhouse with lots of bricks, stone, iron, glass and wood. They flank a lovely Winter Garden with turtle fountains created by the noted animal sculptor, Priscilla Deichmann. The Winter Garden is laid out in Italianate style. It was a little too cold to linger but the design lines and plants like the red-stemmed dogwood, boxwoods and ornamental grasses had strong visual interest even on this bleak day.

Winter Garden with Turtle Fountains

Other semi-tropicals were grown with the wide assortment of citrus trees. My favorites were the camellias which were in full bloom. My friend was particularly enthralled with the coleus and iresine. Both of us admired the clivia, acalypha, agaves and the many other plants that enjoy cool nighttime winter temperatures, say about 45 degrees F or so.


Beautiful semi-tropicals fill the orangerie and limonaia at Tower Hill

As far as I know, this is the only Orangerie in New England. It opened in 1999 and the Limonaia just opened to the public this past fall. While I don’t get to visit Tower Hill or any other horticultural destinations as much as I might like, it is always a treat to be introduced to new plants, both indoors and out especially now as we count down the days to spring and a new gardening season in our own yards.


View of Long Beach

Most of last week I spent in Long Beach, CA at the 2010 ASA (American Society of Agronomy), CSSA (Crop Science Society of America), & SSSA (Soil Science Society of America) International Annual Meeting. This is a phenomenal gathering of 3000 or more scientists, extension educators, industry personnel, federal, municipal and university employees, and graduate students whose careers and studies revolve around soils, water and crops. This year’s theme was ‘Green Revolution 2.0: Food+Energy and Environmental Security.’

New York Times’ columnist, Thomas Friedman, gave the opening keynote on Halloween Sunday. He addressed the main ideas contained in his new book, Hot, Flat and Crowded. In a world with declining natural resources, growing populations,  tumultuous climate change, transfers of wealth and power to ‘petrodictators’, accelerated losses of biodiversity and increasing numbers of  poor, disenfranchised people, he presents a viable solution especially for America. Instead of focusing on ‘Ten things you can do to lower your carbon footprint’, Friedman believes change is needed at the highest policy level and the United States should become a leader in green energy, greater energy efficiency and energy conservation. Listening to him, I felt many of his ideas are just the kind of action that is necessary. Implementing them, of course, would be a challenge but probably less of one than facing the consequences of inaction.

On to two whole days with so many talks on so many subjects that it was challenging to pick which ones to attend. There were way too many to even count! At this conference, topics are arranged into sessions which might spawn a half dozen to more than a dozen 15 minute or so presentations. I chose sessions on Organic Management Systems, Nitrogen Cycling, Soil Carbon, Emerging Contaminants in Wastewater, Integrating the Soil Medium into Current Cultural Media, and Trace Elements in the Environment. I picked up way too many tidbits to share but among them I found out that 27.8 million pounds of antibiotics are given to animals in the U.S. each year as of a 2007 Animal Health Institute report, people may be affected by plant viruses, and pinto beans can take up antibiotics when fertilized with biosolids because not all the human medicines that enter the sewerage treatment plant are degraded when the wastewater is treated.

Wednesday I treated myself to an Agronomy tour as I feel it is important to get out and see some of the science in action and to get a feel for the surrounding area. Plus, I needed to see the sunlight after spending two whole days indoors at the convention center. Our first stop was to the Los Angeles Memorial Coliseum, host to two Olympic Games in 1932 and 1984. While both turf and football are not high priorities in my daily life, it was really fascinating to learn about some of the history behind this stadium – like the movie ‘Two Minute Warning’ with Charlton Hesston was filmed there, both World Series and Superbowl games were played there (the Grateful Dead also played there) and there are rocks there from the Coliseum in Rome and from Altos Olympia in Greece. Mostly I was amazed by the amount of maintenance that went into the playing field. They maintain a primarily bentgrass field with some overseeding of a ryegrass during the cooler months. We got to walk down on the field and it was plusher and more springy than many carpets I have walked on.

Los Angeles Memorial Coliseum

Next stop was the USDA-ARS Salinity Lab on the campus of UC Riverside. What a view I thought. But they did say we were there on a relatively smog-less day and that the mountains were not always that visible. Salinity is a problem in arid areas where crops are irrigated. In hot climates, water is continuously being drawn up to the surface by the heat of the sun. With this water, come salts of all kinds – sodium, potassium, chloride, sulfate, potassium, magnesium- as well as pesticides, heavy metals and boron, among other constituents below the soil surface. As their concentration increases as they move into the soil surface layer it is known that some of these substances are toxic to the crop plants that we depend upon for our food. It is important that adequate leaching and drainage is provided to these crops and also that varieties are developed that can produce a good crop and tolerate increasing salinity levels. It is estimated that at least 15 % of the world’s cultivated land is presently irrigated and that percentage will increase with population growth and face problems of salinity. Several salinity trials were being held when we visited and here is a picture of a strawberry cultivar trial.

Strawberries grown at varying salt levels

 Our visit to the UCR Citrus Variety Collection was impressive. Over 1300 species of citrus (minimum of 2 per species) was grown in these vast citrus groves. Many of you might not be aware that more citrus fruit is grown in the U.S. than all the apples, pears and peaches combined! We got to see, hear and taste some of the citrus collection and also got bags of freshly harvested dates to take with us. What a treat! Fresh dates are a far cry from what we normally have available to us at the local grocery store. If you ever get the chance, try some!

Citrus Collection at University of California, Riverside

After that we visited Milfeld’s Nursery, which specialized in azaleas but also grew camellias, gardenias and hydrangeas, and then Growest Nurseries who raised large specimens of mostly tree but some shrub species. Both were pretty impressive and both noted that since housing starts were down, their business was likewise. Oh, to grow camellias like Milfeld’s did and to have the view off of Growest’s office porch! I can see why folks move to this region of the country!

View from deck of Growest Nurseries

The grand finale of the conference was Jared Diamond’s closing keynote. For those of you not familiar with Jared Diamond he is a professor at UCLA’s geography department. He is also the author of several books including Guns, Germs and Steel and Collapse: How Societies Choose to Fail or Succeed. Being a soil scientist, his message was near and dear to my heart; many of the great civilizations of the past that collapsed were due in large part to their mismanagement of natural resources, especially soil. As their precious soil eroded because of poor stewardship, less food was able to be produced and this was an important factor that contributed to the destabilization of societies and led to their demise. It’s time we all, to quote a popular bumper sticker, ‘Stop Treating Our Soil Like Dirt!’

Incongruous pairing?

A lot has been written about California’s water shortage problems. I have to admit that visiting southern California was a bit of a dichotomy. Many of the residential and commercial landscapes I saw seemed to be too dependent on reportedly scarce water resources. While this past growing season was not as lacking in precipitation as some years (it had been raining in the area for a few weeks preceding my visit) I did expect to find more plantings of drought tolerant plants and fewer irrigated lawns and ornamental beds. Perhaps my uncertainty with their dealings with limited resources is best summed up in this picture with a beautiful drought-tolerant succulent bed on the right and an irrigated turfgrass strip on the other side of the walkway. Which is the best choice for this climate? I’ll leave it for you to decide.

A Weary Traveler,