faq – citrus


For wonderful details and in-depth information about citrus, we recommend Citrus: How to Select, Grow and Enjoy by Richard Ray and Lance Walheim, published by HP Books and available at Harlow Gardens.

Can citrus be grown successfully in Tucson?

Can citrus be grown in containers?

Is there a best time to plant citrus?

Where should I plant my citrus?

How big do citrus grow?

When should I feed my citrus?

Do I need to protect my citrus from frost?

What is causing the flowers to drop from my citrus?

My citrus flowered but did not set fruit. Why?

My citrus did not flower. Why?

Young fruit are dropping from my tree. Why?

Why are the leaves on my citrus turning yellow?

What is creating the holes in my citrus fruit?

How do I know if my citrus are ripe?

What’s chewing on the leaves of my citrus?

The new growth is distorted? Why?

Can citrus be grown successfully in Tucson?

A resounding YES! Some varieties, such as lemons and limes (especially Mexican Limes), are more frost-sensitive, but with a bit of attention on cold nights, especially for younger trees, you can have delicious Grapefruit, Oranges, Tangerines, Tangelos, Lemons, Limes, Kumquats and other, more exotic varieties. Back to Top

Can citrus be grown in containers?

Yes. Dwarf varieties of citrus are the most suitable for containers (with drainage holes). Your container should measure at least 18” wide by 15” deep. Back to Top

Is there a best time to plant citrus?

Spring is the best time to plant citrus, so that they can get a head start on root development before the winter months. However, it is OK to plant citrus year-round as long as they receive appropriate protection and watering. Back to Top

Where should I plant my citrus?

In an area that receives at least a half day of sun. Citrus will thrive in full sun locations. A southern exposure is ideal. Back to Top

How big do citrus grow?

Citrus are often available is three types of trees: Standard, Semi-Dwarf and Dwarf. Final tree size is not always predictable, and will vary depending on growing conditions, variety vigor, climate, and the care you give it. Citrus is rather slow growing and can take 10-15 years to reach full maturity. All types have full sized fruit.

  • Standard – Approximate size at maturity is 20’-30’
  • Semi-Dwarf – Grows to about two-thirds the size of a standard tree. A mature semi-dwarf may reach 15’-20.
  • Dwarf – Most dwarf citrus will reach 6’-8’ at maturity.

Citrus grown in containers will not grow as large because they do not have as much room to grow. The bigger the container the bigger the citrus. Back to Top

When should I feed my citrus?

Feeding of citrus is very important.

Established citrus grown in the ground should be fertilized three times a year-February, May and August. We recommend El Toro Citrus Food 15-10-4 with Iron Chelate and 5% Sulphur.

On a newly planted citrus we suggest incorporating some slow release Osmocote at the time of planting.

Container citrus can be easily fed with a water soluble fertilizer. We recommend Growmore All-Season Plant Food 20-20-20.  Citrus Grower’s Blend, also by Growmore, is a mix of micronutrients recommended for citrus in containers.

If you are an organic gardener, we suggest Growmore Citrus and Avocado 7-3-3 granular or Foxfarm’s water soluble Big Bloom 0.01-0.3-0.7.

Always water your citrus thoroughly the day before and immediately after any feeding.
If in bloom, apply one-half the recommended rate. Back to Top

Do I need to protect my citrus from frost?

On nights when temperatures dip into the low 30’s, young and more frost tender varieties should be covered/protected. Techniques include:

  1. Covering N-Sulate frost cloth [2-3 degrees protection],
  2. Building a frame and covering with plastic,
  3. Covering and then placing Christmas tree lights or a light bulb toward the base of the tree under the covering.
  4. Flooding the basin Back to Top

What is causing the flowers to drop from my citrus?

  1. Mother nature. Citrus produce more blossoms than the tree can set, so it is normal for up to 98% of blossoms to fall without forming fruit; this is nature’s way of allowing the tree to produce only what it can support.
  2. Wind, rain or hail. Blossoms are very delicate and may be knocked off by a forceful wind, heavy rain or hail.
  3. Shock! from a drastic change in watering or feeding practices. Maintain a consistent watering schedule through the flowering and young fruit stages, and apply food only according to label instructions. If feeding when the tree is in bloom, use only half the recommended rate, and water in thoroughly. Back to Top

My citrus flowered but did not set fruit. Why?

Any one or a combination of the following may have caused the flowers to drop before the fruit setting process could take place.

  1. Late spring frost
  2. Low soil fertility
  3. Improper (inconsistent) irrigation Back to Top

My citrus did not flower. Why?

  1. Alternate bearing variety – Mandarins and Navel Oranges often fall in this category.
  2. Too much care and attention! Next winter consider cutting back on your watering (but be consistent) beginning around November 15. It has been suggested that trees that are too well tended may not feel the need to reproduce. Putting just a bit of stress (less water) on the tree may produce the flowers. Back to Top

Young fruit are dropping from my tree. Why?

  1. It is normal to see a lot of small fruit drop right after flowering. This is the result of the tree retaining only the amount of fruit it can support. The usual rule is that when fruit reach the size of a quarter they are there to stay.
  2. When this happens in May and June, this is called “June drop” and is not considered normal. It is believed to be caused by high temperature and low humidity. Check frequently for soil moisture. Fruit drop is aggravated by moisture deficiency. “June drop” usually starts in May and extends through June. Back to Top

Why are the leaves on my citrus turning yellow?

  1. If the leaves are “old” leaves (those most often found toward the bottom or interior of the plant) this is a normal seasonal event that will occur every year. It may also signal a nitrogen deficiency that can be corrected with an application of citrus food.
  2. If the yellowing in on the new growth it is most likely an iron deficiency (leaf veins remain green) resulting from the alkali and excess salinity in our soils. Over-irrigation can aggravate this situation. An application of Chelated Iron will usually solve this problem. In the long run adjusting your watering schedule will be helpful. Back to Top

What is creating the holes in my citrus fruit?

Most likely, it is a bird looking for insects. It usually is not a serious enough issue to worry about, as normally only a few fruit will be affected. Pick the affected fruit and discard. When you see the hole there may be bugs crawling about. These bugs are secondary to the birds, and are not the cause. Back to Top

How do I know if my citrus are ripe?

After your citrus turns its appropriate color, your best information comes from a taste test. Take one off the tree and taste it. Back to Top

What’s chewing on the leaves of my citrus?

That would probably be the Orange dog caterpillar. About 1.5”-2” long, and resembling a bird dropping, these pests can be found on the underside of the leaves. They do no permanent damage and there are usually very few of them. Finding them and picking them off is the best solution. If necessary you can spray with the bacterial insecticide Bacillus thuringiensis. Back to Top

The new growth is distorted? Why?

This is probably the result of thrips, tiny insects that you generally can’t see and they do their damage before you see the damage. Damage is apparent as the leaves and fruit mature. Their damage is generally cosmetic only. Back to Top