Written by Anna-Marie Barnes
This article was first published in Lifestyle Block

I’d like to survey every backyard in New Zealand, from Cape Reinga to Bluff, and count up all the lemon trees. I reckon you’ll find one more often than not, and chances are those trees will usually be the ubiquitous stalwart of the hardy citrus tribe, the Meyer lemon, and not without good reason. The section I grew up on sported a very large, very old Meyer. Upwards of forty years old and a good five metres in diameter, the tree formed a centrepiece in our garden, and my mother recounts regular instances of finding me quite happily stuffing the fruit, peel and all, into my mouth in alarming quantities. For cold-hardiness and reliable production of relatively sweet, juicy fruit, you can’t go past a Meyer, and they are a great starting point. But what of the other, lesser-known, but no less interesting members of the lemon clan?

Lemons: a short family history

The genus Citrus sits within the Rutaceae or Rue family, which is home to all the familiar fruits from grapefruit to mandarin via orange and lime. Other plants of culinary note within the Rutaceae include the white sapote fruit (Casimiroa edulis), curry leaf (Murraya koenigii) and Sichuan pepper (Xanthoxylum spp.).

The cold-hardy Citrus x meyeri is actually a hybrid fruit, not a true lemon, deemed to be a cross between a citron (Citrus medica) and a mandarin/pomelo (Citrus reticulata/Citrus maxima or Citrus grandis) hybrid. Originating from China, where it is known as xiangningmeng, the fruit was introduced to North America in 1908 by US Department of Agriculture employee Frank Nicholas Meyer, who collected a sample from near Beijing. A popular ornamental and container species in China, the Meyer lemon gained popularity in the United States and further afield due to its ability to grow and produce fruit in a wider range of climatic conditions than true lemons or limes, and as a prolific producer of less-acidic fruit with an attractive deep yellow to almost orange hue. Due to the fruit’s soft skin and high juice content, it is less suitable for export than true lemons as it does not store or handle particularly well, although it fares well in domestic markets and as a processing variety.

True lemons, Citrus limon, are thought to originate from northeast India, north Burma or China. This group is genetically diverse, consisting of many different cultivars and hybrid species, and there appears to be no one single wild ancestor. Genomic analysis of this lineage indicates they are likely to be bitter orange/citron (Citrus x aurantium/C. medica) hybrids. True lemon fruit are physically distinguished from the Meyer by being paler in both skin and flesh colour, with a thinner skin, more acidic juice and a distinct, ‘pure lemon’ aroma.

The true or ‘acid’ lemons:

Eureka
A common supermarket cultivar in Australasia, Eureka was developed in California in 1858 from selections made from seed imported from Sicily. The small trees are largely thornless, of moderate vigour, and have sparse foliage. The trees come into production quite quickly. Flowering several times per year, it has its main crop in winter and smaller crops in spring and summer. Fruit is borne in terminal clusters at the ends of branches, outside the canopy. A variegated (both foliage and fruit skin) pink-fleshed Eureka lemon is also available commercially, if you are into flashy specimen trees!

Genoa
Similar to Eureka, the Genoa lemon was introduced to California from Italy in 1875. It is of smaller stature than Eureka, and tends to grow wider as opposed to taller, ensuring ease of harvest. It has denser foliage than Eureka, and is more cold-tolerant. However, like Eureka, it also fruits on the outside of the canopy, leaving the fruit susceptible to damage from wind-rub. It is known to produce fruit almost year-round in Southern Hemisphere growing regions such as Chile – you can expect fruit from July to December in the New Zealand climate.

Villa Franca
Villa Franca is a Sicilian lemon variety and was introduced to the USA from Italy around 1875. It has an open canopy structure and when compared to Lisbon is less thorny, not as upright-growing, and has sparser foliage. Predominantly a winter cropper, it is considered a superior culinary variety due to its highly-flavoured rind.

Lisbon
First grown in Australia in 1824 and of Portuguese extraction, Lisbon is a fairly hardy cultivar, thornier and more vigorous than the Eureka group in growth habit. It is more cold tolerant than Eureka and has dense foliage. It bears its main crop in late winter to spring and another crop in late summer, cropping inside the canopy, meaning the fruit is protected from wind damage. Lisbon is the true lemon most tolerant of climatic extremes, including both high and low temperatures.

Yen Ben
Yen Ben is a sport of Lisbon, selected in Queensland, Australia in the 1930s. It is a popular commercial cultivar (domestic and export) here in New Zealand, where it has been grown since 1978. Thorny when young, it bears its main crop in winter, with smaller fruit than Eureka but a higher yield. The fruit has a thin rind, high juice volume and low seed count.

A note on rootstocks
For reliable, timely fruit production in the home garden, it is best to purchase grafted named lemon cultivars from a reputable nursery or garden centre. Although Meyer lemons can be grown from cuttings and form healthy root systems on their own roots, most other lemon cultivars are grafted onto Phytophthora-resistant rootstocks. Interestingly, citrus are one of the few fruits for which clonal rootstocks can be grown from seed, largely eliminating the need for cutting-grown stocks. The two most common citrus rootstocks for home garden use in New Zealand are Trifoliata (cold-tolerant, high yielding, vigorous growth, compatible with a range of soil types) and Flying Dragon (dwarfing, early cropping, but not as cold-tolerant as Trifoliata). You may notice rootstock growth appearing on grafted trees, low on the trunk, below the graft or bud union – this growth’s foliage will look very different from that of the main tree, with thorny spines and small, three-lobed leaves. Keep this growth trimmed right back to the trunk.

The Kiwi oddities:

Lemonade fruit
The lemonade lemon, or lemonade fruit is another Kiwi backyard beauty, first discovered here as a chance seedling in 1980s. Thought to be a lemon-mandarin hybrid (Citrus limon x reticulata), this easy-peel fruit is sweet enough to eat as-is, makes great juice that doesn’t require sweetening and is a very reliable cropper. The low-acid fruit is a hit with kids and has a mild lemon flavour with a hint of grapefruit. The trees have a compact growth habit and the maincrop fruit matures in the winter months.

The Kaipara lemon and other early arrivals
New Zealand’s oldest lemon tree (and perhaps oldest fruit tree) resides at Rangihoua Bay in the Bay of Islands. Rev. Samuel Marsden arrived here in December 1814 aboard the brig Active, along with three missionaries and their accompanying families. A Thomas Hansen, New Zealand’s first permanent non-missionary settler also resided in this area. Ruatara, chief of nearby Rangihoua Pā, apportioned the missionaries a small piece of land, which they began to farm, as did Mr. Hansen. When Marsden returned in 1819, he noted, alongside grain crops and livestock “…fruit trees sent from Sydney were flourishing…”

The mission site was abandoned in 1832 as the land proved difficult to farm, but reference to a lemon tree growing there was made in an article in the Evening Post of 25 November 1899. Thomas Hansen’s great-great-great-grandson visited the mission site in February 2009 and found a very old lemon tree growing in the vicinity, which based on records and observations has been deemed likely to have been planted shortly after the establishment of the mission – this would mean it predates the famous ‘Kerikeri pear’ by four of five years. Cuttings have since been propagated and planted at other historic sites around the country, and it is now known as the ‘Hansen lemon’. It has been assessed as potentially being an Australian bush lemon or Lisbon type. The photographs I have seen of the fruit online have a crinkly, puckered appearance similar to the bush or rough lemon, Citrus jambhiri, which is a cold-tolerant hardy lemon, often used as a rootstock, originally from subtropical Asia but now naturalised in some areas of Australia.

You may also hear mention of the ‘Kaipara lemon’, described as a New Zealand heritage variety. The fruit is small and knobbly, not unlike the rough lemon in appearance, with soft aromatic leaves suitable for culinary uses and juicy low-acid fruit that can be eaten (thick) skin and all. As such, it is believed to be yet another hybrid, known elsewhere as the sweet or limetta lemon – a citron/bitter orange cross (C. limon/Citrus x aurantium).

Suitable climates and growing conditions
Citrus trees are self-fertile, evergreen, tropical or subtropical plants, and as such lemons will grow well throughout the North Island and upper South Island. The hardier varieties can survive and produce, even in colder areas, if particular attention is paid to careful site selection and the provision of some shelter. Meyers will produce consistent crops with little intervention in Canterbury, and I have heard of Yen Ben producing as far south as Dunedin. If it is particularly windy or just generally cold where you live, but you are determined to grow a citrus crop, you could invest in some sort of protective structure, be it a low-budget citrus house or fully-fledged replica ‘orangery’ from centuries past! If frosts, occasional or otherwise are the problem, consider products such as fabric frost cloth to swaddle your trees with, or wax-like, spray-on ‘liquid frost cloth’ as an intermediate solution. Container-grown fruit may be the answer in far southern climes, as you can shift the plants in and out of a conservatory or greenhouse as the seasons change.

Site selection and planting
Plant your lemon tree any time from late autumn to early spring, but avoid midwinter planting in frosty areas. Select a warm, frost-free, sheltered position where the plant will be protected from strong winds and allow at least four metres of space between plants. Windbreak cloth and stakes for protection in the first couple of years can also be beneficial in marginal conditions. A fertile, well-drained, slightly acidic loam soil is ideal for lemons, although they can crop well in lighter, sandy or clay soils if compost and mulch is applied. A light dressing of fertiliser can be given after planting and mulch around the base of the tree (but kept well away from the trunk) is advantageous. Water well to settle the soil in around the roots.

Culture and care
Lemons are heavy feeders, requiring several applications of fertiliser throughout the year for reliable crops and to maintain optimum tree health. Several proprietary brands of citrus-specific fertiliser blends are readily available, containing the usual nitrogen, phosphorus and potassium, along with additional sulphur, magnesium and calcium plus trace elements. Start with 1.5 kg annually for young trees, increasing by about half a kilo a year to a maximum of 5 kg per year for a large, mature tree. This should be split into at least two applications, two-thirds applied in late winter and the other third in late summer. An alternative regime could see you break the total quantity down into 6-weekly applications from early spring to late summer. Try and apply the fertiliser just before a rain event or water in well after applying. Spread the fertiliser around the base of the tree to the dripline (the zone underneath the outer circumference of a tree’s canopy, where water drips from onto the ground when it rains). Aim for a coverage of about a cupful of fertiliser per square metre of ground.

Irrigation is also of key importance for optimum fruit production, as citrus are not drought-tolerant, although a balance must be struck to avoid overwatering (which results in increased disease pressure) and waterlogging, which is likely to lead to root rots. To ensure plenty of juicy fruit, keep the water up right throughout summer and autumn, as on-and-off watering can lead to dry, pithy, thick-skinned fruit.

You can expect your first crop of fruit two to three years after planting – to help the tree establish, it is best to remove most, if not all, of the fruitlets in the first year or two. I also find that Meyers can crop extremely heavily around the third to fourth year in favourable climates, often burning themselves out in the process. Some judicious thinning helps, remove small or misshapen fruit, fruit that lacks leaves nearby to help feed it, and low-hanging fruit that touches the ground (slugs love to feed on easy-access plant material and lemons seem quite high on their priority list).

Pruning
Lemons, and other citrus trees, generally form their own neat structure and so little in the way of major annual pruning is required. As you harvest the fruit, it is good practise to remove each fruit using secateurs, with a long section of stalk attached (about 5 cm), then cut this off close to the fruit, leaving a nub of stem attached. Removal of this extra wood when picking encourages new fruiting wood to grow. Follow the standard rules for of removing the “three Ds” (dead, damaged and diseased wood) for general maintenance pruning after the main harvest is complete.

Pests, diseases and what to do about them
Lemons are on the hardier end of the citrus spectrum when it comes to pest and disease resistance, but there are a few organisms that may cause issues. Verrucosis (lemon scab) is a fungal disease, and while in terms of fruit production the damage is largely cosmetic, over time the infection can cause a decline in tree vigour, so if your tree is badly affected, you are best to treat it. Brown rot, another fungal disease, can cause significant fruit loss, and its spores will overwinter in mummified fruit and in cankers on branches, so establish a good crop hygiene regime and remove these sources of inoculum from the tree as you find them during the growing season and again at pruning time when the main crop has been harvested. Diseased plant material should be collected up and burned or disposed of with your household waste, not composted. A copper spray timed to coincide with when the petals have fallen and fruitlet formation has taken place in late spring or early summer, and again in late autumn or early winter should take care of both of these diseases.

In terms of insect pests, the main culprits are sucking insects (scales, aphids, mealybugs and whitefly), whose feeding activity and exudates cause black sooty mould to develop on fruit and foliage. Sooty mould on fruit is purely cosmetic, and easily scrubbed off with the aid of a nail brush and some warm water. Thrips, leafroller caterpillars and citrus rust mites can also cause detrimental effects – a vegetable or mineral oil-based spray in February and again in May will help to keep these in check, and there are also softer-option combination products such as pyrethrum-and-oil mixtures or neem oil that combine insecticidal compounds with the smothering effect of oils. It is also worthwhile protecting and encouraging beneficial insect populations in your garden – one of our lemon trees harbours a few sap-sucking guests but also a thriving population of Halmus chalybeus, the steelblue ladybird, the larvae and adults of which are voracious predators of the sucking pests previously mentioned. Other generalist beneficial insects and predatory mites can also help keep citrus red mite populations at bay, so bear these in mind when selecting any chemical controls.

New Zealand has its very own endemic lemon tree foe in the form of Oemona hirta, a longhorn beetle. Otherwise known as the whistling or singing beetle, its penchant for citrus trees as habitat have earned it the moniker of ‘lemon tree borer’. Somewhat of a generalist, the host range of this adaptable beetle now includes a long list of exotic species, as well as the native plants it would have originally existed on. Female beetles lay eggs between September and January, with the larvae burrowing into the wood of branches immediately after hatching, reaching a depth of 10-20 mm. Most of the insect’s approximately two-year life cycle is spent in the larval form, deep within the branches, hence it is very difficult to control. As they consume the wood, their activity creates a network of tunnels within the tree. The formation of these gallery-like constructions can ultimately weaken the structure of the tree and even girdle branches, as well as leaving points of ingress for pathogenic fungi. The larvae pupate after reaching their maximum size in the summer of their second year, and this stage takes upwards of two weeks before they emerge as adults. The adult beetles are active at night, feeding on the pollen on nectar of flowering plants, and are seldom seen during the daytime.

Visible damage to trees may initially be in the form of wilting foliage and/or dieback. Due the larval stage living exclusively inside the tree, the first outward signs of their presence may be exit holes bored to the outside of the trunk, through which powdery frass is excreted. For borer control, there are chemical treatment options available which can be applied through frass exit holes. You can opt to prune judiciously to remove infected branches, avoiding doing this during the egg-laying time period as female beetles will happily lay eggs on freshly-cut wood, and painting all cuts with a wound sealant immediately after pruning. Practise good orchard hygiene, removing all dead and diseased plant material from under your trees on a regular basis, as eggs and larvae can survive for some time on excised plant material left on the ground. There are three parasitoid wasps which are natural enemies of the lemon tree borer, so providing a hospitable environment for these beneficials in the form of shelter, nectar, pollen and using ‘softer’ chemical control options will also assist your management strategy.

What to do with your crop
Now you have a sizeable crop of lemons, where to next? As with all citrus, the most abundant production occurs in winter and early spring, with reduced availability over the summer months. I like to focus on putting away a stash of citrus preserves in a few different formats to bring out when a bit of zip and zing is required out of season. It saves forking out for expensive imported fruit, too.

The first thing I like to do is squeeze and freeze lemon juice in ice cube trays and then free flow the cubes into bags for long storage – handy, as you can take out a few at a time when you only need a small quantity of juice for a recipe. I also freeze larger amounts in recycled 300 and 500 ml plastic bottles (cream containers are ideal) for using to make cordials, syrups and for dipping fruit pieces in prior to dehydrating, to prevent browning.

If you have both chooks and lemon trees, in spring, the citrus glut often coincides with the first egg glut. I take advantage of this and make lemon curd. It only keeps for a few weeks in the fridge, but did you know it freezes and thaws perfectly? I like to use Nigel Slater’s recipe (https://www.theguardian.com/lifeandstyle/2010/mar/07/nigel-slater-lemon-curd-recipes) using four whole eggs. I pack the finished curd into clean plastic containers holding about 200-250 g (recycled hummus or sour cream tubs work well here) and stow them in the deep freeze for up to a year (if it lasts that long!). Thaw the curd in the fridge overnight, give it a quick stir, and it’s just as the day you made it. Make sure you use the thawed curd within five days and keep it refrigerated.

You can easily make marmalade, limoncello (an immensely popular Italian lemon liqueur) and various types of salt-preserved and pickled lemons (recipes abound on the internet). A friend of mine recently passed on a brilliant tip for making use of excess citrus rind: make your own low-maintenance candied peel by layering un-sprayed, un-waxed citrus peels in a sterilised jar with granulated sugar (about an inch-thick layer of each, repeating until the jar is full) and then storing the jar in the fridge indefinitely. A thick, citrus-infused syrup will form as the peel takes up the sugar and releases moisture. You can fish out the amount of peel required for a recipe as you need it, and the syrup will also add a hefty citrus kick to drinks and baking.

I’m going to leave you with my family’s recipe for lemon squash, first made with fruit from the majestic lemon tree of my childhood. It is super-concentrated, and will keep in the fridge for a fortnight, but can be frozen for long storage. Due to the high sugar content, it won’t freeze solid. Dilute to taste with water – it also makes a good addition to a fruit salad, or can be poured neat over Greek yoghurt, muffins or slices of plain cake for added interest.

Lemon squash concentrate
12 medium-large lemons
2 cups granulated sugar
1 cup water

Using a floating blade peeler, remove the rind from six of the lemons and place in a large saucepan with the sugar and water. Bring to the boil, then turn down and simmer for about 15-20 minutes – in my mother’s terminology “until the skin thingies get crinkly”.

While the rind mixture is cooking, halve the lemons and squeeze the juice into a jug or bowl.

Remove the rind mixture from the heat and cool to room temperature. Add the lemon juice, stir well, and then strain the whole lot through a sieve, composting the solids.

Store in the fridge in a sealed container for up to two weeks, or freeze for up to 12 months.

Anna-Marie Barnes is an active member of the New Zealand Tree Crops Association who endeavours to grow and preserve as much of her own fresh produce as possible. When the weather’s no good for gardening, she can usually be found inside working on a batch of homemade cheese or soap.

The New Zealand Tree Crops Association is a voluntary organisation promoting interest in useful trees, such as those producing fruit, nuts, timber, fuel, wood, stock fodder, bee forage and other productive crops. Find out more about the NZTCA here: https://treecrops.org.nz/

Image credits:
True lemon
Elena Chochkova, CC BY-SA
https://commons.wikimedia.org/w/index.php?curid=3145063

Meyer lemon
D. Barnes