Thursday, January 5, 2023

Citrus for cold climates and warm homes


I’ve described our glassed-in front porch aka solar greenhouse in a previous post, but I haven’t talked about the citrus trees that I keep on it during the winter, aside from the time that the weather outside became so cold that some of them died. Here’s what I have learned about the varieties of citrus that I can grow successfully in containers on our front porch, for those of you in cold-winter climates who may wish to add home-grown citrus to your diet.


The 2014 cold spell was much harder on the citrus plants than I had realized when I wrote that post. It turned out that the only citrus tree on the porch that survived was the ‘Meyer Improved’ lemon, and not without damage. Because the satsuma tangerine was small enough to move into the house, it survived as well. I replaced the dead trees with a ‘Lisbon’ lemon, a ‘Bearss’ lime, and a ‘Meiwa’ kumquat. This set of trees grew well.


By early 2019, the tangerine had fruited a couple of times, though not profusely. The ‘Lisbon’ lemon sported its first crop of 8 large lemons and we were looking forward to their ripening! But then an ominous weather forecast prompted me to move the kumquat, lime, and Meyer lemon into the basement to avoid potential sub-freezing temperatures. The Lisbon lemon and the tangerine were bigger, enough so that it made it difficult to move them into the house. I chose to leave them on the porch. Both froze to death. (We did juice the frozen lemons … the juice was delicious.)


With this many years of experience I feel confident that I can now provide recommendations on the best citrus to grow in containers for those of us who are forced by cold winter conditions to move them inside our homes for part or all of our winters. These trees are easy to care for, are attractive especially when in bloom or when covered with ripe fruits, and provide excellent fruits that ripen in winter to add some freshness to winter meals. They are small enough to be placed in a basement or in front of a good-sized window inside the house, if you don’t have a greenhouse or a space like our front porch that can be made into one.



My ‘Meiwa’ kumquat tree, shown above, is covered with small fruits that pack a much larger taste than their size suggests. In my opinion, kumquats are the best choice for anyone with limited space that allows for only one plant (my 9 year old plant is about 3 feet wide and tall). Because you eat the whole kumquat except for the seeds – in fact, the peel is the sweetest part of a kumquat! – there is little waste. Like other citrus, the flowers have a strong floral odor. It blooms later than the lemon and lime trees, in the summer rather than in the spring. I just harvested the first four kumquats and should be harvesting fruit for the next few weeks as each one ripens. A kumquat tree may live through a very light frost but should be moved out of the cold when temperatures drop below 30F.


For those of you who like limes and have room for a somewhat larger plant, I suggest the ‘Bearss’ lime. My lime tree (above, with the yellowish fruits) is about 4 feet wide and about 4 ½ feet tall at 9 years old. The juice from a ‘Bearss’ lime has the classic lime flavor. My current tree has withstood temperatures a degree or two below freezing, but I bring it into the house when the porch gets any colder than that. I’ve picked 8 limes so far this winter, with another 5 to pick later on. They are ripe when the skin turns light yellow. Each lime weighs 2 to 3 ounces.


‘Meyer Improved’ lemons can weigh up to a half-pound each and have a good lemon flavor, though not quite as good as the Lisbon lemons. My ‘Meyer Improved’ lemon, above, is going on 20 years old and is about 4 feet wide and 5 feet tall. It only bore 5 lemons this year but each lemon weighed 6 to 8 ounces! It can stand a much colder temperature than the lime or kumquat trees, down to 20F or even colder, though temperatures that cold can damage it.



The photo above shows the trunk damage that my lemon tree sustained in the 2014 cold snap.


In my experience, navel orange, satsuma tangerine, and Lisbon lemon trees all eventually grew so large that I could no longer move them from the porch to the house when we experienced a cold snap. This doesn’t mean that they might not work for you, but if you choose them I suggest that you have a good pair of pruners on hand and learn how to prune them to keep their size small enough that you can move them into and out of the house when you need to.


Caring for these trees is similar to any houseplant. In between your last spring frost and first fall frost, they enjoy living outdoors in a sunny spot. Keep the soil moist but not wet and fertilize them on occasion so that they will have enough nutrition to fruit. I like to pot mine in a mix of garden soil, compost, and earthworm castings and fertilize them with diluted urine once every week or two when they are outside. When they are on a porch or inside the house, they grow so slowly that they don’t need any extra fertilizer. The soil can be drier when they are inside, but not completely dry. If you start to notice drooping leaves and stems and the soil is dry, they need water. They do not seem to be especially attractive to insect pests except for scale, and the scale that is on the lime tree doesn’t seem to bother it that much. A good time for potting them on and for pruning is when you move them outside in the spring, so that they will have time to regrow their roots and branch framework before they go dormant. Lime and lemon fruits often drop off the plant when they ripen, but picking them first will ensure that they don’t bruise where they hit the floor. The fruits keep for weeks in the refrigerator and can be used in the same ways you use lemons and limes from the grocery store. We also candy the lemon and lime peels and coat them with melted chocolate for a homegrown treat!


I wish all of you a happy 2023! When next we meet, I’ll report on the 2022 garden.