Citrus are magnificent fruit trees native to Asia and introduced to Europe by the Arabic civilization. From there, they spread to America.
Like the orange tree, lemon tree and kumquat, most of the time citrus have evergreen leafage and only grow directly in the ground in regions where the winter climate is mild.
Grown for example in the Mediterranean area, they are more and more commonly found on our terraces, decks and patios, which makes them very trendy nowadays.
In cooler regions, they’re grown in pots, so that they can be brought out of the freezing cold over winter.
There is of course the lemon tree, the orange tree, the clementine and the pomelo tree which produces grapefruit.
Additionally, you can find kumquat, also called Fortunella margarita, which produces cute tiny fruits to savor.
Lastly, the only citrus suitable for indoor growing inside a heated house or apartment in winter is the calamondin.
Calamondin fruit is far too sour to eat raw, but it makes excellent marmalade and flavours drinks beautifully.
The main citrus grown at home differ mostly in the fruit they give and in how well they cope with life indoors. This overview sets them side by side before you commit to a tree.
| Citrus | Fruit |
|---|---|
| Lemon tree | Lemons |
| Orange tree | Oranges |
| Clementine | Clementines |
| Pomelo tree | Grapefruit |
| Kumquat (Fortunella margarita) | Tiny fruits to savour |
| Calamondin | Indoor orange tree fruits |
Whichever you pick, full sun and a frost-free winter shelter matter more than the choice itself.
Kumquat is among the hardiest of these citrus, though yuzu is generally reckoned tougher still, and it overwinters well in a cool, frost-free shelter that is barely heated.
The pomelo (Citrus maxima) bears pomelos, not grapefruits; it grows into a large, vigorous tree and needs plenty of heat to ripen its fruit, so it suits a small terrace poorly.
Prefer a grafted tree over a seed-grown one; it will flower and fruit years sooner.
Areas that border the sea in Mediterranean type climates like the American South-East and South-West coasts are very well suited for cultivating citrus plants.
There, they can be planted outdoors without much risk.
Full sun exposure is important for best fruit-bearing.
Further North, if you inhabit a region where it doesn’t freeze, you can plant them in the ground on the condition that they be well protected from wind and in a space well endowed with sunlight.
If it does freezes in your area, favor potted growing or growing in garden boxes and bring your citrus inside an unheated lean-in for instance, which will be quite cool in winter but won’t freeze and endanger them.
The variety best suited to growing indoors is calamondin, which is an indoor orange tree that can stay in the same room year-round.
Potted growing as an indoor plant for the other citrus plants isn’t problematic either, except that they must spend winter in a cooler room.
Refer to our guidance on how to best care for your potted citrus lemon tree and orange tree. In fact, for other citrus plants, the guidelines are almost exactly the same.
Keep the graft union clear of the compost when potting.
Choose a pot only slightly wider than the root ball, because a large volume of damp compost around few roots encourages rotting.
Citrus resent soggy peat-based compost, so use a loam-based mix lightened with coarse sand or composted bark.
Move the tree up one pot size when roots appear at the drainage holes, and simply replace the top few centimetres of compost in between.
Use rainwater or filtered water whenever you can, since hard tap water leaves lime in the pot and turns citrus leaves yellow between the veins.
Water until it runs from the drainage holes, then tip the saucer out.
Cut watering right back for citrus overwintering in a cool lean-in, where growth slows and wet compost quickly rots the roots.
Leaves that yellow and drop while the compost stays damp point to too much water, not too little.
Citrus bear fruits from November to May, except for lemon trees which can bear fruit all year round.
Indoors, fruit formation is much more difficult. As your experience grows in caring for your citrus, you’ll end up getting better at obtaining fruits from your plants.
Citrus are non-climacteric and will not sweeten after picking, so leave fruit on the tree and judge readiness by tasting a sample, since rind colour alone is an unreliable guide to ripeness.
Indoors there are no pollinating insects, so dab a soft brush from flower to flower to move the pollen yourself.
A citrus often carries flowers and swelling fruit at the same time, so check branches for developing fruit before shortening them.
You can prepare cuttings and layering (August is best for this).
Citrus pips germinate readily, and because most common citrus are polyembryonic, their nucellar seedlings are usually clones of the parent, though such seedlings stay thorny and juvenile for years before fruiting.
A seed-raised citrus also takes many years to flower, whereas a cutting or layer carries the parent’s fruiting maturity with it.
More or less every 2 years, in the month of March.
Prune lightly to renew the vigor of your citrus plants.
As an example, look at what it takes to prune finger lime, a particularly thorny variety.
Keep cuts light: citrus blooms on new spring shoots that emerge from buds on wood grown the previous year, so a hard cutback removes much of the growth carrying the coming crop.
Wipe your secateurs with alcohol before moving to the next tree.
Do not strip the canopy bare: citrus bark scorches badly once exposed, and newly uncovered branches are best shaded or painted with white latex.
Read also:
Silvery winding tunnels and puckered, curled young leaves are the mark of citrus leaf miner, which attacks soft new flushes rather than mature leafage.
Indoors, dry heated air favours red spider mites: inspect leaf undersides for fine webbing and dull stippling, and mist the foliage to raise humidity around the tree.
Leaves that turn yellow while the veins stay green indicate iron chlorosis, common on citrus watered with hard tap water; switch to rainwater and apply chelated iron.
Most species have thorns, but you can cut them off at any time. This helps protect fruits, but it also makes caring for the tree much more comfortable!
