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Growing Citrus Indoors

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Growing Citrus Indoors

Have you ever thought how fun it would be to have your own lemon tree or an orange tree in your own home?  The flowers of citrus plants are delightfully fragrant, usually with thick snow white petals on flowers that pollenate, seemingly, like magic. We have been growing citrus trees, in pots, here at the Kemper Center for quite a few years now.

We had a calamondin orange tree (Citrus x calamondin) for about five or six years. It was just a 6 inch cutting when we began. The fact that it was a cutting from a mature tree meant that it could produce fruit without the six or more year wait for a seedling to be mature enough to produce flowers.  As the calamondin grew in size we gradually took it outside in the summer time. The calamondin orange tree is now over 5 feet tall and is over in the Linnean House, full of flowers. 

In our Kitchen Garden we have grown multiple citrus from seed. At this time we have a small Key lime (Citrus aurantiifolia). This is a plant that we started from the seed of the fruit purchased at the grocery store. Because this plant is a seedling and not mature enough to produce flowers and fruit it may be from 4 to 8 years before it is mature enough to produce limes.

We also have a giant lemon (Citrus ‘Ponderosa’) (pictured). This lemon tree produces flowers and fruit all year round. It takes nearly three months for a pollenated flower to produce a lemon. These lemons mature to a size about that of a grapefruit. However, the tree is only about two and one half feet tall.

Citrus need sufficient water for new growth, flowers and to produce fruit that have an extremely high, moisture content.  When watering citrus at a rate to meet their needs, it is important for the container to be porous. In plastic pots, the top of the soil may appear dry when soil at the bottom of the pot is still wet. The plastic does not allow the roots at the bottom of the pot to retain sufficient oxygen and that often leads to rotting roots. That is why terracotta flower pots work so well, because they are porous and allow the roots to have moisture and oxygen at the same time.    

Our plants here at the Kemper Center are growing in a bark based potting mix with some calcined clay added. This is a clay product that looks like kitty litter but it has no added chemicals. Calcined means that it is baked at a really hot temperature. This makes the clay very stable in the soil. The calcined clay works by absorbing excess moisture while still leaving the moisture available to the plant.  

The food or fertilizer that you supply for citrus can make a big difference in how well they grow. A complete fertilizer with micronutrients is important. Most soils have sufficient calcium, however, most potting soils do not. Also, many fertilizers are lacking calcium. An easy way to supply the extra calcium needed for good flower and fruit production is by adding eggshells to the soil. Eggshells left to dry naturally in a brown paper lunch bag, scrunched up and added to the soil is like “Mother Nature’s slow release calcium.” One other supplement that is very beneficial to citrus is potassium silicate.  Potassium silicate makes the cell walls of the leaves much stronger and can make the plant more tolerant to drought, disease, and insects. This comes in liquid form by several different brand names, that you can mix with water or as greensand.  Greensand is a natural product that is from certain locations often near the sea coast that naturally has potassium silicate in it, along with other trace minerals. These two supplements together can work like a magic potion for citrus plants grown in containers.

Many garden centers are now offering a variety of different citrus and one may be right for you. To see our giant lemon, key lime and our other exhibits, come and visit the Kemper Center for Home Gardening. 

Jane Roth
Horticulture Assistant Kemper Center for Home Gardening

| Categories: Summer | Tags: orange, citrus, indoor plants | View Count: (13014) | Return
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