Cultural Requirements of Citrus Trees

Citrus trees have lovely bright green foliage & fragrant flowers, are valuable as ornamentals or orchard trees and their fruit is an excellent source of Vitamin C.

Citrus trees are not difficult to grow but do have certain requirements that need to be met. Citrus are affected by cold and accumulated heat. Taking advantage of microclimates around your house may aid you in growing these cold-sensitive fruits.

The following lists citrus in order of most tender to most hardy:

• Lime
• Lemon
• Grapefruit
• 'Bearss' Lime
• Sweet Orange
• Most Mandarins
• Meyer Lemon
• Satsuma Mandarin
• Kumquat

Citrus Are Sweet on The Heat, Not the Cold

The most tender foliage can be damaged at temperatures of 32°F, while the most hardy citrus like the satsuma mandarin and kumquat, can stand temperatures down to 20°F. Keep in mind these trees are well established trees, not newly planted trees, and the duration of low temperatures is not sustained. Most fruit will be damaged at 26-28°F. If damaged by a frost, most citrus will still produce fruit the following year.

Citrus also need a certain level of accumulated heat in order to ripen. Since lemons are eaten for their acidic taste, they don't need the accumulated heat in order to sweeten up and are therefore suited for cool, coastal climates. Grapefruit and oranges need a high-accumulated heat and only reach peak quality in hot inland and desert areas.

Site Selection

Before actually planting your citrus, make sure the site you select is appropriate for your tree. Citrus needs 8-12 hours of light per day to produce a good crop of fruit. If the tree is not receiving sufficient light, the crop will be thin or none at all. If putting into a container for indoor growth, select a southern facing window to get the most sunlight.

Before planting or potting up, try placing the tree in the desired location for a couple of weeks to see how it responds. If the tree looks unhappy, try another location.

Planting Instructions

Fruit trees are a lifetime investment and caring for them properly, right from the start, will insure years of enjoyment and productivity. The greater the investment in early care, the less maintenance that will be required as the tree matures.

• Dig a hole twice the width of the root ball.
• Place the tree in the hole so that the root crown, where the roots meet the trunk, is higher than ground level, to account for soil settling.
• Add the fill soil, mixed with high quality soil conditioner or organic matter, back in and water thoroughly.
• For potted citrus, use a mixture of potting soil, perlite or pumice and peat. The mixture should be nice and "fluffy". Do not use potting soils with wetting-agents, they don't like soggy soils.

Citrus must have well-drained soil as they are sensitive to water-logged soils. So if planting into the ground and you have heavy soils, make sure to amend it with compost and even some pumice to help with the drainage. However, they prefer deep infrequent watering. If the soil is dry 2" down, it is time to water. Unsure about when to water, try a moisture meter for help.

A soil analysis is also recommended to determine any soil deficiencies, but this can be delayed until the tree has begun to establish itself. A gradual application of proper soil amendments will suffice if proper sunlight and drainage are available from the start.

Fertility of Citrus Trees

For well-balanced mineral soils, a yearly application of an organic fertilizer, such as Cottonseed Meal or Compost, is ideal. It should be applied in late Winter or early Spring, on the surface in a broad ring around the plant, regardless of plant size. However, in the long-term, calcium, magnesium, phosphorus and potassium along with sufficient nitrogen will significantly enhance tree health and fruit quality. The yearly addition of phosphorus or potassium or both are also important for fruit production.

Citrus also benefit from application of micro-nutrients such as zinc, iron, manganese and magnesium, if these are at low-levels in your soils. Container grown citrus might need more frequent applications of nitrogen since nitrogen may be leached by waterings. There are several high quality citrus fertilizers available such as Down to Earth, E.B. Stone and California Organics.

Frost Protection

To avoid damage by frost, protect trees with Agribon Rowcovers. For details, see our blog on Season Extending Techniques online. If trees are planted in containers, move them inside or to a greenhouse during cold weather.

Pruning Citrus

Citrus need little pruning and then only of its dead or broken branches. You may need to remove suckers from younger trees. Lemon trees need the most pruning of their vigorous branches.

Harvest

In general, the hotter your climate, the earlier you can harvest. Fruit grown on the coast ripen last. Color is not a good indicator of ripeness. The best way to tell when to harvest your fruit is by taste.

Enjoy your citrus, protect it during harsh times, and it will bear you a beautiful crop of juicy fruit!