Of all the cultivars of citrus that are popular for home gardens, the ‘Meyer’ lemon is likely the most popular. However, it is not overly common in markets. That may be an incentive for growing it at home. Technically, it is not totally lemon. It is an odd hybrid of lemon and orange. Hence, its fruit has a distinctly rich flavor, but a bit less acidity than other lemons.
‘Meyer’ lemon is distinct among citrus trees. It grows more like rigid shrubbery, with a few irregular trunks. Because it naturally develops compact form, it does not require dwarfing understock. Most old trees therefore grew from cuttings on their own roots. Modern trees commonly grow on understock though, so can develop suckers below their graft unions.
‘Meyer’ lemon fruit is abundant during autumn and winter. Minor quantities ripen through spring and summer also. All ‘Meyer’ lemon trees from nurseries nowadays are ‘Improved Meyer’, whether or not their labels say so. Their improvement was selection of stock that lacks a particular tristeza virus that was inherent to the original cultivar prior to the 1940s.
Winter is the primary season for citrus fruits. Some ripen significantly earlier. Some ripen significantly later. Many citrus trees continue to produce a few fruits randomly throughout the year. Nonetheless, citrus fruits are collectively most abundant during winter. It seems odd that trees that are vulnerable to frost are so productive during the coolest of weather.
Citrus trees are fortunately only marginally susceptible to frost in only the cooler climates here. They mostly recover from minor damage where they get a bit too much chill. Those in coastal climates may never experience damaging frost. Some types of citrus are more resilient to frost than others. Vulnerable citrus trees may need frost protection when new.
Home garden citrus trees are different from orchard trees. Most orchard trees, particularly older trees, are ‘standard’ trees. They grow on standard rootstock that allows them to get larger, and therefore produce more fruit than ‘dwarf’ trees. Most home garden citrus trees are ‘dwarf’ trees. They grown on dwarfing rootstock that keeps them dense and compact.
Furthermore, the many cultivars of citrus that are available for home gardening are more diverse than those that commonly grow in orchards. ‘Lisbon’ lemon is very profuse within season, so is preferable for orchards. ‘Eureka’ lemon, although a bit less productive, may be a preferable option for home gardens because it produces a few random fruit all year.
Now that citrus are in season, some last longer than others. Grapefruit can hang on their trees for months. They actually develop richer flavor with mellowing tartness as they age. Conversely, Mandarin orange and tangerine are the most perishable citrus. Because the rind is loose, their pulp within begins to oxidize after ripening. Lime eventually gets pithy.
Although this is the time of year to enjoy fresh citrus fruits, it is not the season to do much else with citrus trees. Pruning and application of fertilizer will be more timely after winter. Premature pruning or use of fertilizer is likely to stimulate premature growth. Such growth either languishes through cool weather, or succumbs to mild frost.
Winter seems like an odd time for fruit to ripen. Winter weather is cool enough to inhibit vascular activity in plants. That is why most plants are dormant to some extent through winter. Most familiar fruit trees are deciduous, so defoliate in winter chill. Stone fruits ripened through early summer. Pome fruits ripened through late summer and autumn. Nonetheless, citrus fruits are now in season.
The various citrus fruits and their cultivars ripen at various times through their season. Like stone fruits and pome fruits, they are on distinct schedules. Furthermore, climate affects ripening. Citrus fruits that ripen earlier than other cultivars in a particular climate may ripen after the same other cultivars in another climate. A few cultivars produce sporadically, or notably later than citrus season.
Such cultivars are justifiably popular. For example, ‘Eureka’ lemon is a mutant of ‘Lisbon’ lemon. ‘Lisbon’ lemon works well for orchards because all the fruit ripens within a limited season. ‘Eureka’ is more practical for home gardens because it instead produces sporadically throughout the year. A few fresh lemons are always available. The winter crop is abundant, but not too overwhelming.
Mandarin oranges are the first citrus fruits to harvest, even if they are not the first to completely ripen. Because their rinds fit so loosely, they are the most perishable of citrus fruits. They will oxidize and dehydrate before they rot. Tangerines are the same, since they are merely American descendants of Mandarin oranges. ‘Rangpur’ lime is not a lime at all, but a sour Mandarin orange hybrid.
Oranges, lemons and grapefruits, although ripening now, can remain on their trees for quite a while. The tartness of grapefruits mellows with age, and might be preferable after a few months. The same applies to the acidity of lemons. However, too many lingering citrus fruits can inhibit bloom. Some limes are supposedly best before totally ripe. All citrus fruits stop ripening when harvested. Juice of the various citrus fruits can be frozen for storage if necessary.
Tony Tomeo 