‘Lisbon’ lemon actually came first. It is still grown in orchards for lemon juice and other lemon products. The glossy evergreen foliage is a nice bright green. The late winter bloom is nicely fragrant. Mature trees can be kept about twelve feet tall, or allowed to get much taller. Besides the nasty thorns, the only other problem is that all the fruit ripens within a limited season.
‘Eureka’ lemon, Citrus limon ‘Eureka’, is a mutation of ‘Lisbon’ that is more casual about its schedule. It produces a good quantity of fruit in season through the end of winter, and also produces lesser quantities throughout the year. Because it is so productive, the lesser quantities should be more than sufficient whenever lemons are needed.
The ‘Variegated Pink’ lemon is a mutation of ‘Eureka’, so is a mutation of a mutation. The foliage is nicely variegated with white. The green fruit is striped with yellow until it ripens to yellow. The pulp and juice are pink of course. Like many variegated plants, the ‘Variegated Pink’ lemon stays much smaller than ‘Eureka’ lemon, and is more sensitive to frost.
It may not be the mother of all lemons, but Lisbon lemon, Citrus limon ‘Lisbon’, is the original cultivar from which ‘Eureka’ lemon was derived; and ‘Variegated Pink’ lemon was later derived from ‘Eureka’ lemon. ‘Variegated Pink’ is still uncommon, and the pink juice is unusual, but because its variegated foliage is less efficient than greener foliage, it is more manageable in small spaces.
The only distinguishable difference between ‘Lisbon’ and ‘Eureka’ is the scheduling of the fruit. Both are the biggest of the dwarf citrus, and can get as tall as second story eaves. Both have nicely aromatic glossy green foliage. Both are somewhat thorny, and get big thorns on vigorous growth. Yet ‘Lisbon’ is now rare, while ‘Eureka’ is second in popularity only to the unrelated ‘Meyer’ lemon.
That is because, after primary winter production, ‘Eureka’ continues to produce sporadically throughout the year, which is what most of us want in our home garden. ‘Lisbon’ may seem to be more productive, but only because it produces all of its fruit within a limited season that is finishing up about now. The fruit that ripens now may linger for months, but no new fruit ripens until next season.
When life gives you lemons, it is likely this time of year. Although, the most popular garden varieties of lemon, like ‘Meyer’ and ‘Eureka’, continue to produce at least a few more fruits sporadically through the year. ‘Lisbon’ lemon that is still used in orchard production, and is the ancestor of the household ‘Eureka’ lemon, produces almost all of its fruit in winter, and blooms shortly afterward.
Ripe citrus in the middle of winter impresses those in climates where winter is too cold for much to happen in the garden. They could not grow a citrus tree if they wanted to. Even here, frost can damage some of the more sensitive citrus varieties, like ‘Mexican’ lime. Unlike the fruits of summer, citrus fruits ripen slowly and are not so perishable, so do not need to be harvested right away.
This means that if it is raining, cold or just to wintery to go outside, citrus fruits can be left on the tree until the weather improves. Most of us prefer to pick them in small batches anyway. Ideally, fruit should get picked as it is consumed. Lemons and limes typically get picked individually as needed, until there are so many that some need to be bagged and shared with friends and neighbors.
Mandarin oranges are the most perishable of the citrus. Because their skins are so loosely attached to the pulp, the pulp can oxidize, lose flavor and eventually get dry and pithy. Incidentally, a ‘tangerine’ is merely a Mandarin orange that was developed in North or South America. A surprisingly sour (unknown) Mandarin orange might really be a ‘Rangpur lime’, which is not a lime at all.
Unlike most fruit that continues to ripen after harvest, or pears that actually delay ripening until after harvest, citrus fruits stop developing flavor once picked. It is best to taste them for confirmation of ripe flavor prior to harvest. Some Mandarin oranges may have slightly greenish blotches on them even when completely ripe. The best ‘Valencia’ oranges can look rather yellowish. Grapefruits might mellow if left in their trees past ripeness, but can also inhibit bloom.