How can you tell if a plant is over- or underwatered?

[Want Them All]

I'm constantly struggling with this issue with many of my fruit trees. The avocado has barely any leaves left, most of 'em are real small, and just fall off if I rub lightly on the branches.

The guava tree has curled up leaves, feel dry to the touch. Just 3 weeks ago the guava was healthy looking, I unintentionally dumped a 5-gallon bucket of water around it. Maybe it choked on the water? Since that episode, I've watered it once a week, letting the soil dry out before watering. I've heard that if a plant is overwatered its leaves will look sick and fall off. If it's underwatered, the leaves will also look sick, but do not fall off (until much later when the plant is dead). Is that correct?

Thanks,

[sunfish]

www.tropicamango.com/avocado.html

[planetrj]

One last thing..aside from watering over/under... there's another issue, depending on the var.: Even though you're in Ca, and we're not in the land of torrential rain, it's good to know this for the winter/spring in your area...Some Guavas don't like rainwater, and it can damage the foliage. Beaumont Red, Mexican Cream and Feijoa Sellowiana are just a few that aren't crazy about rain. Cattleia (sp?) Red and Lemon are both very comfortable with any amounts of rain. One thing that they all need lots of though is sunlight. They will brown and drop leaves quickly if they have too much shade. I hope you figured it out one way or another.

Originally Posted by Want Them All

I've heard that if a plant is overwatered its leaves will look sick and fall off. If it's underwatered, the leaves will also look sick, but do not fall off (until much later when the plant is dead). Is that correct?

[sbl]

Originally Posted by Want Them All

I've heard that if a plant is overwatered its leaves will look sick and fall off. If it's underwatered, the leaves will also look sick, but do not fall off (until much later when the plant is dead). Is that correct?

Thanks,

I don't know about the leaves, but in most cases the symptoms are very similar, because in either case the plant can't get enough water (when overwatering kills the roots--the plant can't get water). The difference is in the soil and watering history. Soils that are too fine or have turned to muck can hold water for a long time. A fast draining media will require more frequent watering, but will not likely rot the roots.

[Richard]

Originally Posted by sbl

I don't know about the leaves, but in most cases the symptoms are very similar, because in either case the plant can't get enough water (when overwatering kills the roots--the plant can't get water). The difference is in the soil and watering history. Soils that are too fine or have turned to muck can hold water for a long time. A fast draining media will require more frequent watering, but will not likely rot the roots.

I agree.

Here's some more tips ...
Leaves cupping upwards is a sign the plant needs a deep watering.
Avocado leaves browning around the edges is a sign of alkaline salts in the water supply or soil.
Leaves of plants browning around the edges and then falling off or turning uniformly yellow and then falling off is a plant dieing of thirst.
Leaves browning around the edges but otherwise healthy is a sign of chemical "burn".
Leaves with green viens but yellowing in-between is typically over-watering but in general means the plant is not getting enough nitrogen. In the case of over-watering, this is from the roots being choked by water-saturated soil.

[Want Them All]

Great info! I'll have a close look at both trees today.