Overwatering & Underwatering Citrus Trees

Knowing how to water citrus trees is key. Most indoor watering issues are the result of overwatering. Folks have the tendency of adding water when their tree is looking sickly, but sometimes this just makes things worse.

Watering your citrus trees may seem like a simple chore but it is one of the major problem areas most growers encounter regularly. Underwatering and overwatering are common issues for those growing outdoors and especially indoors. Overwatering tends to be less of an issue during the summer months since the soil dries out much more quickly. Sometimes citrus trees can be water multiple times a day when extremely hot. That same tree’s soil indoors could take 3+ weeks to reach the same level of dryness.

When should I water my tree?

Factors include:

  • Time of Year
  • Indoors or Outdoors
  • Age of Tree
  • Health of Tree
  • Water Tolerance/Resistance of Cultivar
  • Period of time since the last watering
  • The volume of water used during the previous watering

Try taking frequent soil moisture readings after watering and tracking the number of days it takes to get down to 40% or less on a soil moisture tester. If you have more than one tree, make a mental note listing out your trees ordered by the frequency of watering. Species, the age of the tree, health, and time of year all factor into the watering demands of citrus trees.

If unsure of which, put a finger into the soil down about an inch and half to figure it out.  If the soil is dry, underwatering may the issue but there could also be any number of nutritional deficiencies among other factors.

If the soil very moist or you have been watering frequently recently, you could very well have an overwatering problem. Citrus cultivars can range widely in terms of tolerance towards more frequent watering. For this reason, the deep watering method is the recommended method for watering citrus. This is in comparison to more frequent waterings with a consistent and smaller volume of water per time.  Deep watering is done so that you know exactly when to

Also, beware that symptoms of watering are similar to some nutrient deficiencies too. Be familiar with the appearance of leaves and possible causes before jumping to any conclusions. As with anything, use your best judgment. You probably know the last time you watered your tree or applied fertilizer. That’s important information that you’ll find difficult to derive simply by visual observation yet it’s information that can be crucial for an accurate prognosis.

Methods and Tools For Determining Soil Moisture

In order of cheapest to most expensive:

Your Finger

Most of us have at least one finger! You don’t need to spend a penny to dip your finger into the soil to see if it’s wet, moist, or dry. The downside of this approach is accuracy. Misreading the soil moisture level in a way where the soil is actually still quite moist but watering the plant because you think it’s dry can lead to a number of overwatering issues. Potentially, a series of incorrect measurements the soil moisture can cause your tree’s leaves to fall off and eventually kill off the plant. If you have a few dollars to spare I recommend upgrading to a soil moisture tester.

Soil Moisture Tester

Purchase Now

This little physical meter is fairly inexpensive. They can be purchased on Amazon for 10ish dollars and even cheaper if shipped directly from China. One meter can be reused for many containers. One or two soil moisture testers will suffice for most home growers.

This typical moisture meter has three color-coded ranges: dry, moist, and wet. When you hit the red range, you should definitely water. In the summer, with warm temps and your trees outdoors, plan on watering in the lower end of the moist range. If you don’t the soil could be bone dry the next time you check the following day.

Soil Moisture Sensor

Now this option is pretty techie and maybe even a little overboard for most indoor citrus growers.

This electronic moisture sensor can be used on a Rasberry Pi, Arduino, or similar device platform. Investigate your option first. I’ve found the cheaper ones are far less reliable and you are probably better suited to spend a little bit more for something more accurate. Being off by soil moisture by 20%, for instance, can lead to devastating ramifications! Even eventual death! That’s why I recommend spending a little extra for something more precise that can be relied on. Buy one and test it out first before bulk ordering to save money.

Water Tolerance and Resistance

You can research specific cultivars to figure out how they can weather long rains and how long they can go without water. For instance, an Australian Finger Lime can go without water for a duration longer than most other citrus trees making it a much more suitable patio plant in places like Arizona and New Mexico over other alternatives.

Symptoms of Underwatering

The fix is pretty obvious! Water your tree. What may not be so obvious are the symptoms.

  • Drooping leaves. You’ll notice pretty uniformly across the tree the leaves will begin to sag like it isn’t strong enough to support the leaf.
  • Blossoms or new leaves seem like they are forming but die off prematurely. There simply isn’t enough water to support this new growth, so the tree is intelligent enough to cut its losses before expended more resources into an already lost cause. When this occurs, don’t expect the tree to immediately flush out new growth(it may happen), but sometimes you’ll just have to wait a weeks before anything happens.
  • Fruit drop. This is an extreme edge case. You’ll have droopy leaves and blossoms and new leaves fall off before the fruit drops, so it must have been quite a long time ago before the tree hasn’t received any water(assuming it’s indoors) or it could have been a relatively short period if it’s the middle of summer and incredibly hot(maybe just a few days).

Symptoms of Overwatering

Overwatering can be quite a bit more complicated than underwatering. People oftentimes mistake overwatering for underwatering, further escalating the issue.  If you have made this mistake, additional measures may be necessary to course correct your tree’s health. If you haven’t overwatered too much, simply skip watering until the soil is dry an inch and a half down.

If the condition of your tree does not improve, you may have root rot. This occurs when water stays next to its roots for a prolonged period known informally as “getting wet feet”. Resting your pot on a concrete or some rocks that heat up can expedite the process of drying out the soil. In the winter time, using a hair dryer on a moderate heat setting around the outside of the container can also help dry out the soil more quickly. This dry out the perimeter of the container first with limited ability to dry out the soil near the center of the pot. Our goal isn’t to evenly dry out the soil; rather decrease the overall soil moisture. Drying out the soil near the outside of the container will aid in drying out the center indirectly since the less moist soil will be adjacent to it.

Make sure your pot drains well. If outdoors and the weather has been particularly rainy, move your tree under a canopy or an area where it won’t receive any more rainfall.

In more extreme cases, you may consider repotting your plant and cutting away the rotting roots. If possible, do this in the Spring or Fall.

Delay watering your tree until its condition has improved.

When Should I Water my Citrus Tree?

Citrus trees like a deep watering roughly once per week in the spring and summer. Adjust your schedule once they go dormant in the fall to once every two weeks or slightly longer.  Any automated watering system should be programmed to water an equivalent outdoor amount at a similar interval.

Use a soil tester meter. This is a step up from the good ‘ole put a finger in the soil trick, you won’t get dirty with a water meter. On a scale of one through ten, whenever the number gets down to four water again.

When you move your citrus trees inside, try to have a reading four to six. Let the soil dry out a little more before watering again. Since it’s the off-season, your trees will need less water than before. Cut the frequency of watering to once every three weeks or thereabouts.

Other Potential Problems