Lemons

Every garden needs a lemon tree

The lemon tree has a number of attributes that qualifies it for inclusion in the modern garden’s list of core plants. When it is laden with fruit it makes an eye-catching tree, especially in a small garden. As it is evergreen, it will provide a certain amount of shade all year round. It will grow and produce fruit quite willingly in a large pot, making it ideal even for very small gardens and on sunny patios.

Since the earliest times, lemons were known for their many useful properties. They were eaten to prevent scurvy and the juice was used as a beauty product to lighten skin and hair. In royal gardens, lemon trees were grown in elegant, wheeled, wooden caskets. In warmer weather the palace gardeners would move the trees outside for everyone to admire. When the cold weather arrived, the trees would be returned to the conservatory.

Today, lemons are used extensively in cooking, baking, for medicinal and cosmetic purposes. It is hard to imagine a life without lemons.

Selecting the right lemon tree

Most citrus trees, including lemons, are propagated by the process of budding the required cultivar onto a suitable rootstock. This ensures trueness to type, early maturity and thus fruit borne on a young tree, as well as disease resistance, amongst many other benefits as opposed to growing from seeds. Be sure to purchase or acquire your trees from a reputable source, making sure that they are budded (similar to grafted) onto a good solid rootstock. Young trees should be straight with healthy, lush green foliage and no signs of pests and disease. Make sure that they are not root bound in their nursery container. There should be a balance between the size of the tree and the container that it’s growing in.

Planting the lemon tree

Lemon trees need a full-sun position in the garden. They are best planted directly into the ground but can be successful in large pots or containers for a number of years. Potted citrus tends to lose condition once their roots become pot bound, which depends largely on the volume of soil in the pot.

Planting holes must be well prepared – there is absolutely no point in planting a good lemon tree into a meagre hole in poor soil. Dig large square holes at least 500 x 500 x 500mm. Larger is preferable. Add compost and kraal manure along with root-promoting fertiliser like bonemeal or superphosphate at the recommended rates for the size hole that you are preparing. Make sure that all the ingredients are well incorporated with the garden soil before filling this back into the hole. If the soil is dry then fill the hole with water and allow it to drain away before returning the prepared soil mixture to the hole. This ensures that the surrounding soil does not absorb the water that is used to supply the young, newly planted tree.

Dig a hole in the centre of the prepared soil large enough to accommodate the root ball with comfort. Carefully remove the tree from the pot or bag and place the root ball in the hole, making sure that it’s at the correct depth. When complete, the soil level of the root ball must be the same as that of the new surrounding soil. In other words, do not bury any deeper than the level of the nursery bag. Additional soil built up around the stem can cause a problem called collar rot.

Fill in with soil around the roots and firm down thoroughly. Build an irrigation basin around the newly planted tree with any excess soil. This should be about 500mm away from the stem all the way around the plant. This ensures that water is channelled to the root zone and does not simply flow away into the garden. Once complete, water thoroughly. Continue watering well every 4 – 6 days for the first three months after transplanting. The period and amount of water depends on the weather conditions.

Maintaining the lemon tree

Once the tree has been planted it’s advisable to tie it to a strong stake. This prevents wind damage and makes sure that the tree grows straight and upright. Do not tie the plant too tightly as this can damage the bark on the stem. Regular inspection of the young tree is part of the process of having a good lemon tree. Check that it has sufficient water. Inspect for any rootstock growth below the bud scar on the stem and remove it carefully.

Most suitable climate and location

Lemon trees prefer a warm, subtropical climate with a high rainfall, but once well-established they will flourish just as well in other climates, including the winter rainfall regions and other colder areas. Some types withstand cold winds and frost better than others, but you would be wise to protect all young trees against strong winds frost, or to plant them in pots placed in a sheltered area or against a north-facing, sun-baked wall. Lemon trees will flourish in coastal regions provided that they are protected against salt-laden sea breezes.

Soil: Lemons prefer well-draining soil as a general rule of thumb, however, they have been seen flourishing and bearing copious quantities of fruit in clay soils. In the case of the latter, it is important to work organic matter into the clay before planting and mulch the surrounding soil after planting with the same material.

Water: trees in the ground need a regular, deep watering at least twice a week during dry spells in the summer. Potted trees require more frequent watering during hot weather, possibly even daily. In her book, Companion Planting (Briza Publications 2007), Margaret Roberts recommends that you place a long pipe in the corner of the planting hole, forming an irrigation tube. Water poured into the pipe goes directly to the roots, ensuring that the tree always gets a deep watering without any water going to waste. Check on watering regularly, especially during prolonged periods of dry weather. Apply water as soon as any signs of wilting appear on the leaves.

Fertilising: lemon trees are greedy plants and need to be fed three times a year with fertiliser rich in nitrogen and potassium. The nitrogen encourages better foliage while the potassium improves the quality of the flowers and fruit. Feed in September, January and late March/early April, starting with an 8:1:5 or 5:1:5 and, later in the season, using a 3:1:5 as the climate starts to cool. A handful of Epsom salts for added magnesium also does wonders for the tree. The fertiliser should be spread below the dripline (furthermost point of the outer leaves) and not around the trunk. Water the plant well after feeding.

For potted lemons, try a liquid fertiliser containing additional nutrients.

Pruning

Generally, lemon trees do not require regular pruning, but old trees can be cut back hard to rejuvenate them and initiate a new lease of life. Prune out any straggly growth or dead wood that may appear from time to time.

When do the flowers and fruit appear?

The sweet-scented, waxy blossoms are an attribute the lemon tree shares with all the citrus family. In the case of some lemon varieties these delightful flowers appear practically all year round and it’s not uncommon to see both the blossoms and fruit on the tree at the same time. However, springtime (especially October) is generally flowering season, and the fruit usually matures in the winter months.

Problems to watch for on citrus

Be aware of any insect pests or fungal diseases and treat them immediately.

Fruit dropping off: if some of the small fruit starts dropping off, the tree is probably shedding them deliberately because there are too many to ripen. Fruit can also fall off in heavy wind or during a drought.

Yellow leaves and poor growth: the most important requirement for growing lemon trees is well-drained soil, so remember that you can improve heavy clay soil by adding organic material and coarse river sand to the planting hole. Soaked roots and excessive watering can cause yellowing of leaves or they may even drop off. A lack of nitrogen or magnesium can also cause paler leaves; correct this by mixing trace elements or Epsom salts with water (use a watering can) and pouring it around the tree.

Deformed fruit and branches full of thorns: this could be an indication that the root stock is beginning to grow from beneath the point where the variety was grafted onto it. If this appears to be the case, remove these stems and branches immediately. Drought and poor drainage can also lead to irregular growth.

Pests: the best protection against pests that commonly attack lemon trees is companion planting. Plant nasturtiums, lavender and marigolds around your trees. Lavender and marigolds deter pests with their strong scent, while nasturtiums attract aphids away from the trees. Remember, however, that the lemon tree is a host plant for the beautiful yellow and black Citrus Swallowtail butterfly as its leaves provide food for the newly hatched larvae. If you notice tiny caterpillars munching the leaves, just leave them alone as your tree will throw new leaves once the feasting has stopped and the larvae have entered their pupal stage.

Scale and aphids: if scale and aphids become a problem, spray the trees with a canola-oil-based organic spray during the winter months. Aphids can also be sprayed off with a strong jet of water or, in the case of young trees, rubbed off with your fingers. Never spray with a poison as you may wish to use the leaves to flavour a dish you are cooking. Systemic poisons (those that are absorbed through the roots) must never be used on any edible plant!

Control the ants: ants are attracted by the sweet secretion (honeydew) that aphids leave behind on the leaves and stems. If not controlled, the ants will spread the eggs of the aphids to new plants. There are many products on the market to treat ants. Nip-It by Protek works wonders.

Citrus psylla: the adult psyllid, which looks like a winged aphid, lays its eggs on citrus leaves. When the young psyllid, in the form of wingless nymphs, emerge from the eggs they feed on the leaves, causing wart-like galls and leaf malformation. The damage is unsightly but unless the infestation is severe it is unlikely to place the tree in danger. Natural predators, which play a big role in controlling psyllid populations, are susceptible to the formulations used to control citrus psylla so the most environmentally-friendly cure is to remove the affected leaves by hand – or just look the other way as you will when you spot the Citrus Swallowtail larvae.

For more on pests click here

Different lemon cultivars

Different lemon cultivars are propagated and grown around the world, and locally there are 5 or 6 that are readily available. Each has its own value and virtues. Some are smaller in stature while others are more cold resistant. Consider these cultivars – some are more readily available in nurseries and garden centres than others.

‘Eureka’ – Vigorous growing, medium to large tree. Smooth-skinned fruit with yellow skin and greenish flesh with few seeds. High acidity and lots of juice.

‘Genoa’ – Medium to large tree. Smooth-skinned fruit with yellow skin when ripe, and yellow to green flesh. Acidic and juicy.

‘Lisbon’ – Large tree of great vigour. Medium size smooth-skinned fruit with yellow skin and pale flesh. High acidity and juice content.

‘Meyer’ – Small tree of compact habit. Small fruit with yellow to orange skin and yellow flesh. Less acidic than other lemons with plenty of juice.

‘Rough skin’ – Large tree with a gnarled look. Fruit with rough skin and odd shapes. Yellow when ripe with pale flesh. Acidic and moderately juicy. This is an old-fashioned lemon tree that’s been cultivated locally for ages. Usually propagated from seed, so it takes far longer to bear fruit than the other cultivars that are budded.

Lemon advice

When you pick lemons, leave a piece of the stem on each as this allows them to last longer. You can also leave the fruit on the tree and only pick when it’s needed;

Fill tall glass cylinders with water and pop in some lemons for elegant table décor;

Soak lemon (and other citrus) peels in a bucket of water for a few days and use the liquid to water young plants and cuttings. According to seasoned gardeners the pith contains a growth stimulant and rooting hormone;