Citrus as houseplants

Citrus as houseplants

When I was a girl I was always starting citrus trees from seeds of an orange, tangerine or grapefruit that I had eaten.  I had some of these trees for many, many years and some of them got quite large.  But they never gave me flowers or fruit.  Had I moved to Florida or California and planted them in the ground they may have given me fruit, but as a houseplant that wasn’t going to happen.

I see many people writing about planting citrus seeds they get from table fruit and wondering how to care for them. Like me as a child, they are probably going to get plants, but unless they live where they can plant them outside (Zone 8 and above) or they have a large heated greenhouse they probably aren’t going to get fruit or even flowers.  Since citrus do make nice looking house plants if cared for and pruned correctly that may be all right with them. 

But there are citrus varieties that gardeners can grow inside in tubs and if you are lucky you will get sweetly scented flowers and possibly fruit.  I have yet to see a plant outside of a greenhouse that looks like the pictures in the catalogs, loaded with full sized fruit, but I have seen plants, including my own, that will produce flowers and a few fruits for you.

There are naturally dwarf citrus trees and citrus that has been grafted onto dwarf rootstock.  These smaller trees are better for home environments, and will flower and fruit more reliably and at a younger age than full size citrus.  You’ll probably have to buy plants or start a cutting from a natural dwarf variety.  Seeds from a natural dwarf, like the Meyer Lemon may produce a nice plant for you, bur seeds from grafted plants will produce full sized trees that will take many years to bloom, if ever.

Some good varieties of citrus for indoor growing are Meyer Lemon, dwarf Key Lime, Red Finger Lime, Kaffir Lime, ‘Bearss Seedless’ lime, ‘Mexican Sweet Lime’ Changshou Kumquat, ‘Christmas’ Loquat, Citrus ‘Limequat’, Myrtle Leaf orange, “Sanguinelli’ blood orange, ‘Vaniglia Sanguigno’ blood orange, Calamondin orange, ‘Autumn Gold’ navel orange, ‘Washington Orange’,  ‘Trovita’ orange, ‘Miho Wase’ Satsuma Mandarin orange, ‘Tango’ Mandarin orange, Clementine orange,  ‘Oroblanco’ grapefruit, dwarf tangerine.

How to grow

When growing citrus indoors use a good light weight potting mix.  Make sure the containers you select have good drainage.  Don’t put a small plant in a pot that’s too large for it.  When you first bring home a small potted plant let it adjust to conditions for a couple weeks before re-potting it.  Then move it to a new container only slightly larger than the one it was in.  You’ll probably have to re-pot your citrus every year, or every other year, until you reach the largest pot size you can handle.  Then you’ll prune the tree to keep it a reasonable size for the pot.

Because clay or ceramic pots are heavy and citrus plants need consistent moisture, I prefer plastic or lightweight fiberglass type pots for larger plants.  As long as you can move it and it drains well though, use any pot that appeals to you.

Citrus must have very bright light inside.  They must be right in front of a south or southwest window if no artificial light is used.  Sunrooms and south facing bay windows are excellent.  If you don’t have good southern light you’ll need a grow light suspended a foot from the top of the tree.  The citrus trees need about 12 hours of good light a day.

Citrus trees must also have plenty of space.  Yes those catalog pictures of 2 feet tall trees with fruit are cute, but not common.  Even though most indoor citrus are considered to be dwarf plants they get to at least 5-6 feet tall in most cases.  They need large pots at this size, which adds to the height.  They will also get wide- especially if pruned to reduce height.  At maturity expect them to be 3-4 feet wide.

Probably the best way to grow citrus is to move them outside in full sun (with acclimation), after there’s no danger of frost and leave them there until just before first frost in fall.  This will generally produce the healthiest, most productive plants outside of a warm greenhouse environment.  The trees with a good summer vacation may drop some leaves when moved back inside but will generally survive the shadier winter conditions fairly well.

When you are ready to move the plant outside, you should first place it in a lightly shaded location for a few days to let it acclimate.  Some protection from wind is desirable, such as in front of a fence or a few feet from a wall.

Citrus plants need even consistent watering.  Outside in containers they need to be watered quite frequently, maybe once a day in hot weather.  Inside you’ll want to let them dry slightly before watering.  The leaves will roll inward and droop a bit if the plant is too dry.  Don’t over water citrus though, too wet soil will cause rotted roots, which can be fatal.  Trees that are overwatered may look limp or lose all their leaves because the roots have rotted.

To get flowers and fruit you’ll need to fertilize your citrus plant.  Since citrus likes slightly acidic soil I use acidic fertilizer for mine.  You can buy citrus fertilizer in some areas, in the north look for fertilizers for blueberries or evergreens.  When you are re-potting a plant you can work some acidic granular, slow release fertilizer into the soil and this will last several months.

After that time is up and between re-potting use a water soluble acidic fertilizer on your citrus from March to November.  Mix according to label directions.  Don’t fertilize in the lowest light periods of November to March.

Sometimes potted citrus will develop light green leaves with darker green veins. This can indicate an iron deficiency.  I find this is less likely to happen when acidic fertilizer is used, but it still happens sometimes.  You can buy chelated iron for plants in a good garden shop or on line.  This is mixed in water according to label directions and used to water the plant.  The plant should become darker green after two or three watering’s, and you can discontinue use of the iron supplement. 

Other problems of citrus indoors can be scale, aphids, and whitefly. Scale usually looks like brown bumps or scabs on the tree branches and leaves.  If the tree is outside you can spray it with 1% horticultural oil.  Don’t spray when the tree is flowering.  Inside use a mild solution of insecticidal soap and a soft toothbrush and gently scrub the scales off.  Aphids and whitefly can be caught with sticky traps.  A spray of insecticidal soap may help. If the tree isn’t flowering and has no fruit other insecticide sprays can be used.

The yellowing and dropping of a few leaves ever so often is normal for citrus trees.  This is more likely after the plant has been moved and conditions have changed.  Cold temperatures can cause leaf drop too.  Keep indoor citrus above 50 degrees.

Pruning

Pruning citrus can be done at any time, although I would avoid it when the tree is flowering.  Prune off any broken, dead or unusually spindly looking branches. Look for the graft bulge on the stem of a grafted plant and remove any sprouts that develop under the graft.  

Usually indoor citrus are pruned to maintain a manageable size.  Cut back the height to the size you prefer each year and trim back some of the width if desired.  Use clean, sharp pruning shears and don’t take off more than 1/3 of the tree at any time.  Make your cuts just above a leaf node on the stem, on a slight slant.  You don’t need to seal cut ends.

Flowering and fruit

It can take several years for a citrus plant to flower even in ideal conditions.  If it doesn’t get enough sunlight and proper watering and fertilization it may never bloom.  Citrus can bloom in the spring or fall or both, depending on the species and variety.  Most citrus blooms are white and small.  Sometimes they go unnoticed unless you notice the sweet smell most citrus flowers give off.

Citrus are generally self-fertile which means you only need one plant to get fruit.  But they have to be pollinized to get that fruit, and in nature, insects pollinate citrus flowers.  If your tree is outside when it flowers bees may pollinate it for you.  Inside you have to stand in for the bees if you want fruit.  In northern areas you may want to pollinate the flowers yourself even if the plants are outside when they bloom.  Bees may not notice unfamiliar flower odor or shape for a while.

To hand pollinate flowers get a small paintbrush.  Brush it across the yellow anthers of one flower and then across the stigma- female part of another flower. The stigma is usually in the center of the yellow anthers, has a flat “top” and will look glossy or sticky when ready to accept pollen.  Be like a busy bee and do this back and forth between all the flowers once a day until they close or fall.

If you are lucky and the flowers got pollinated small fruit will begin to form.  This is where patience comes in.  If there are a lot of fruit forming it’s natural for some of it to fall off, called self-culling.  Low humidity can also cause fruit to abort.  It’s a good idea to mist citrus plants with fruit several times a week if your indoor humidity is below 50%.

Citrus fruit can take from 6 months to 18 months to ripen, depending on species.  Normally it will change color to the normal ripe color of that species fruit.  When it’s deeply colored try lifting a fruit slightly.  If it comes off the stem easily it is ripe.  All fruit may not ripen at the same time.

Don’t expect a large crop from any indoor citrus plant.  Most people are pleased to get a few fruits each year.  It’s my experience that these indoor citrus fruits are smaller than outdoor grown fruit of the same type, but they taste perfectly fine.

A citrus tree can make a fine houseplant and a great conversation piece if it flowers or fruits.  It’s a challenge to some gardeners to grow their own delicious fruit inside.  Start with a healthy, nursery grown plant for best results.  And remember when you start growing your own citrus fruit it’s probably time to consider that sunroom or greenhouse.