Categories: Latest News and Information

The Different Types Of Lime Trees & How To Grow Them

Citrus trees are some of the most popular small evergreen trees in Australia, and lime trees are definitely up there in terms of the best Australian fruit trees.There are at least twenty types — including hybrid varieties — but the most popular are the Kaffir Lime, Tahitian Lime, Finger Lime and the Key Lime. Here is our guide to the types of lime trees and how to grow and care for them.

Kaffir lime tree (Citrus hystrix)

Sometimes known as the Makrut lime, the kaffir lime tree has long peanut-shaped leaves and produces rough, pith-filled fruit. Native to the tropics of Southern China and Southeast Asia, these plants are most often used for their leaves, which can be used fresh or dried to add flavour to Southeastern cuisines. Kaffir lime leaves are renowned for being one of the most aromatic herbs and add a unique and distinctive flavour to many dishes, including in Lao, Thai and Cambodian soups, stir fries and curry pastes.

Kaffir lime trees can grow up to four metres tall, but because the leaves are often constantly picked for cooking, they will often remain smaller. Branches are typically strongly spined, but thornless varieties are available. They are a great addition to a garden and can be grown in a pot or in well-drained soil. They need lots of sun and only mildly cold winters, but are pretty resilient once they begin to fruit and are protected from frost and extended cold periods.

Tahitian lime tree (Citrus aurantifolia)]

The Tahitian lime tree is another popular lime tree and has seedless fruits and thornless branches, unlike other lime tree varieties. Foliage is glossy and evergreen, providing a wonderful backdrop for its fragrant white flowers. When do lime trees fruit in Australia? In this variety, the fruit-bearing season is from mid-autumn to mid-winter, although they can produce fruit year-round. Fruit production may also increase every year. Small and green when ripe, they can be left on the tree until they turn yellow. Plants grow to around three metres tall, and grow very well in the garden, as a potted lime tree, for hedging, or as feature trees.

They are also easy to maintain and are one of the best low-maintenance trees for your garden. They are generally pest and disease-free but prefer warmer clients and are reasonably frost tolerant. However, in particularly cold areas, it is recommended to wait until spring before you plant. The Citrus X latifolia is a well-loved variety that fruits from autumn to spring and bears lots of fruit, so your kitchen will be well stocked! It can grow up to four metres tall, but there are also dwarf Tahitian lime trees that grow up to two metres tall.

Australian finger lime tree (Citrus australasica)

Native to Australia, the finger lime tree is unique compared to other lime trees. It has smaller than usual leaves and thorny branches, but also beautiful elongated finger-shaped fruit that is brownish red. The leaves are smaller than traditional lime trees, so they form a dense crown of foliage that offers birds and other native wildlife shelter and protection. When the fruit is opened, magnificent caviar-like pearls are revealed, and they have a wonderful texture, and a distinctive un-lime-like pulp, so they are often used in jams, sauces, drinks, garnishes, and Thai cooking. Closely related to the domestic citrus, the tree grows up to six metres tall and is ideal for pots and garden beds. This lime tree prefers warm zones but may tolerate cooler areas provided it is in a warm, protected spot throughout winter.

Key lime tree (Citrus aurantiifolia)

Native to Southeast Asia, the Key Lime is also known as the West Indian, Mexican, or Omani lime. It has a spherical fruit that is usually picked while still green, and it becomes yellow when ripe. The name comes from its association with the Florida Keys in the US, where it is best known as the flavouring ingredient in Key Lime pie. Its tree is shrubby, grows up to five metres and has many thorns. Dwarf varieties can also be grown indoors during the winter months and in colder climates. Its trunk, which rarely grows straight, has many branches, and they often originate from quite far down the trunk. Its flowers are yellowish-white with a light purple tinge on the margins. The tree flowers in the spring, with fruit following in late spring to early summer. However, if the flowers fall off without bearing fruit, the tree is not yet mature enough to bear fruit.

Lemon lime tree

Also known as a Splitzer lime tree, lemon lime trees are two different trees that have been grafted together — a lemon tree and a lime tree or often two types of lime trees. These can be different combinations of citrus trees — for example, a Meyer lemon tree with a Tahitian lime tree. If the pairing is done right, your tree will grow evenly and equally as the tree develops over time and produce luscious crops of fruit. Size is not a problem either, as these trees thrive in both the garden and in a pot. If grown in a garden, they can reach a height of two metres and prefer a sunny but sheltered position. In a pot, they will be more restrained and, therefore, smaller, particularly if pruned. Monitor the plant’s watering with the weather — less in cooler weather, more as the temperature heats up. It should also be regularly fertilised to maintain its health and ensure you have bountiful crops of fruit.

How to care for lime trees

Different species of lime trees may require slightly different care techniques, so you should follow the instructions provided when you purchase your tree or ask for advice from your local nursery. However, many lime trees typically have similar requirements, so here are some generic tips.

Where do lime trees grow best?

Lime trees prefer warm climates and thrive in sub-tropical, tropical and warm temperate areas. In cooler climates, a Tahitian Lime tree is more tolerant of colder conditions and can withstand light frosts once established. A Finger Lime tree and a Kaffir Lime tree can also grow in cool areas but require a warm, protected spot over winter. For better success in cool climates, grow lime trees in pots. This will allow you to move them to the warmest part of the garden during the day (like in front of a north-facing brick wall) and move them indoors at night if required.

How much sun do lime trees need?

Lime trees prefer at least six to eight hours of sunlight, and windy sites should be avoided, especially when establishing young trees.

What is the best soil for lime trees?

Most trees need rich, well-drained soils. Heavy clay or poorly drained soil must be improved before planting, as these trees don’t tolerate a wet root zone. To check if your soil is poorly drained, dig a hole and pour a bucket of water into the hole. If it takes more than 30 minutes to disappear you should improve your soil. Regarding the best pH for lime trees, they prefer a neutral or slightly acidic soil pH (from 6.0 to 7.0). Soil that is too alkaline can be made more acidic, and soil that is too acidic can be made alkaline with various products on the market.

How much water do lime trees need?

Lime trees should be regularly watered after planting. Once established, they are fairly drought tolerant but will benefit from deep watering at least once or twice a week, particularly during hot, dry spells.

When do lime trees produce fruit?

Most lime trees have their peak fruiting season from autumn to spring.

When should I harvest lime tree fruit?

Trees will start to bear fruit about two years after planting. While small fruit may develop sooner, it’s best to remove them, and this will encourage better-sized and better-tasting fruit to grow in the coming years. Limes are ideally picked while they are green, tangy and under-ripe. However, if left on the tree, they will yellow, and the fruit will become slightly sweeter. Fruit from the finger lime tree (Citrus australasica) is ready to be picked when it is full of pulp, and the fruit comes easily off the tree.

Should I remove the flowers and fruit from a young lime tree?

Yes, it is best practice to remove flowers from young citrus trees for the first few years so they can put their energy into developing a sturdy root system and branch structure.

How long does it take for a lime tree to become established and fruit?

For most citrus trees, it takes three to four years for a well-cared-for tree to become established and fruit well.

When is the best time to plant a lime tree?

The best time to plant a lime tree in cooler climates is in spring and in temperate and warmer areas in spring and autumn.

When is the best time to transplant a lime tree?

Spring is the best time to transplant a lime tree from one position in the garden to another.

How to grow lime trees in a garden

Choose a location. Choose a spot in the garden that receives at least six hours of full sun daily and has good drainage, as lime trees don’t tolerate poorly-drained soil. In areas with poor drainage, elevate the lime tree by creating a twenty-centimetre-high mound of free-draining soil and plant the tree into this mould.
Dig the planting hole and improve the soil. Dig the planting hole twice as wide and to the same depth as the root ball, then rough up the hole’s edges with your shovel. Fertiliser can then be added at this point. Remove the plant from the container and gently tease the roots, cutting away any tangled roots. Position in the hole, backfill with enriched soil, and gently firm down. Form a raised ring of soil around the outer edge of the plant’s root zone, which will help keep water where needed. Then, water well after planting to settle the soil around the roots.
Early lime tree care. Keep the soil moist for several weeks while the new plant is established. Mulch around the root zone with organic mulch like sugar cane or pine bark mulch, keeping it away from the base of the trunk.
Watering and feeding lime trees. Lime trees generally need lots of nutrients to promote a great harvest, so they should be fertilised every eight weeks from spring until the end of harvest. This will promote healthy leaf growth and lots of flowers and fruit. A finger lime tree requires specific care. They need a fertiliser that’s safe for Australian native plants. Apply around the root zone every spring and autumn and water thoroughly two to three times a week, depending on the weather conditions.

How to grow lime trees in a pot

Choose a pot and a location. Choose a pot at least 40 centimetres in diameter with good drainage holes. Ensure the pot is placed in a wind-protected position that receives at least six hours of sunshine daily.
Plant your lime tree. Part-fill the pot with a quality potting mix. Remove your lime tree from its container and gently tease the outer roots. Place the root ball on the potting mix and backfill around the roots with the fresh potting mix.
Early care for a potted lime tree. Water the tree well and keep the potting mix moist for several weeks while the new plant establishes. Apply mulch like sugarcane, pea straw or bark chips around the root zone, keeping it away from the tree’s trunk. Mulch will help keep the potting mix moist and the roots protected.
Watering and feeding a potted lime tree. Potted lime trees should be watered thoroughly — two to three times a week, depending on the weather conditions where you live. They also require lots of nutrients to promote a good harvest, so they should be fertilised every one to two weeks from spring until fruit is harvested to encourage lots of fruit, flowers and healthy leaf growth. A finger lime tree should be fed with an appropriate native plant fertiliser — around the root zone every one to three weeks from spring until the end of harvest.

How to grow a lime tree from seed

Growing a lime tree from seed will differ depending on the source of the seed. As a basic guide, a Tahitian lime tree seed is generally hybridised, so the seeds are highly unlikely to breed true, so you probably won’t get the same fruit. A Finger Lime tree, Kaffir Lime tree and a Key Lime tree typically produce true-to-type plants, meaning they will be the same tree as the original source. Many lime trees from retailers are often also grafted onto rootstock that keeps the tree more compact. Growing a lime tree from seed can take up to 15 years for the tree to mature, but if you have the patience, here is a basic guide:

Prepare the seeds for sowing. Remove the seeds from the fruit and gently wash to remove any pulp. Then, soak the seeds in a glass of water for a few hours before discarding seeds that float to the surface.
How to sow seeds from lime trees. Fill some seed trays or small pots with an appropriate seed-raising mix. Insert seeds approximately 1.5 centimetres deep into the mix and then lightly cover with more mix.
How to care for lime tree seeds. Position the trays or pots in a warm, brightly lit spot out of direct sunlight. Gently water and keep the mix consistently moist.
Germination time of lime tree seeds. Germination time can take anywhere from a few weeks to a few months.
When to re-pot lime tree seedlings. As a general guide, seedlings should be repotted when they are ten to fifteen centimetres tall.

How to prune a lime tree

While pruning a lime tree isn’t mandatory, it can boost fruit production and contain its growth (particularly if it’s planted in a pot). Pruning citrus trees allows sunlight and air to enter the plant’s shaded areas. It also guides the shape and size of your lime tree, particularly if your plant is in a small garden or pot. In terms of when to prune lime trees, the ideal time is before blooming, which is typically from early spring through late summer.

In terms of how to prune a lime tree, gardening experts recommend using a sharp set of pruning shears and cutting away any dead, damaged or diseased twigs or limbs. Neat cuts should be made close to the main branch or track so they create a smooth surface to allow the tree to avoid causing stress to the tree. Any suckers should be cut away as they will drain nutrients from the upper parts of the tree. Fewer branches will encourage fewer fruit, but they are likely to grow bigger. When pruning back healthy branches, cut them at an angle to discourage water from entering the cut. Never trim away more than a third of the upper tree.

Common problems of lime trees

Like most plants, lime trees can be susceptible to diseases and pest infestation. The most common issues include:

Leaf curl. If you find a curly leaf on a lime tree, it could be due to a range of factors, including a lack of water. Give your plant a good drink!
Yellowing leaves. This can signal your lime tree needs warmth and nutrients, so boost its health with a good dose of fertiliser.
Pests. Sooty mould, citrus leaf miners, scale insects and aphids all love lime trees, which can be avoided with a recommended pest oil. A problem with citrus leaf miners is easy to identify, as you’ll notice silvery, squiggly lines on your tree’s leaves. Small bumps on the stems, fruits or leaves typically indicate evidence of a sap-sucking pest called scale. If you notice tiny crawling insects at the tips of wilting citrus leaves, it is probably due to aphids. They are also sap-sucking pests and excrete a sticky substance that attracts ants. If you notice the stems and branches of your tree are lumpy, swollen or bulging, it is probably due to citrus gall wasps. The best treatment for these is to prune off infected stems to remove any galls as soon as possible, particularly before winter. Lime trees can also be prone to borer, which is the larvae of beetles and moths. Trees affected by these are usually those that haven’t been properly cared for. The best cause of action is prevention by ensuring your tree is fertilised and has the right amount of sun and water.
Leaf damage. Various pests consume or damage lime tree leaves, including snails, slugs, caterpillars, rats, birds and possums. Caterpillars, snails and slugs can be removed with a pest spray. Possums can be deterred with netting or wire, but there are also possum-repellent sprays and rat deterrent gels available. Netting is the best option to deter birds, although many gardeners also swear by hanging shiny objects nearby or placing a scarecrow near the tree!
Leaf loss. Lime trees are also prone to root rot and collar rot, particularly if they are in poorly drained soil or during prolonged wet weather. Trees can rapidly start to wilt, shed leaves and die. To avoid this, plant your lime tree in well-drained soil in full sun, avoid overwatering and keep any mulch away from the base of the trunk.
Flower loss. Lime trees often produce many more flowers than they can turn into fruit, so it is normal for trees to drop some flower buds. However, excess flower shedding may indicate a problem with a lack of moisture or nutrients.
Dry fruit. Soils with low phosphorus or excess potassium or nitrogen can cause dry flesh and the fruit’s rind to thicken. Citrus fertiliser is your go-to here!