Nutrient leaching (and its prevention)

lathechuck's picture

I've been tending three exotic potted plants for about two years: an olive tree, a lime tree, and a kumquat tree. These plants sort of fell into my lap when I visited a yard sale in my neighborhood, and happened to have use of a pickup truck to take them home for very little money. (I think they were $15 ea., for trees over 3' tall.)

They live on my concrete-slab patio during the warm seasons, and behind a west-facing bay window during the winter. During the first winter, the citrus bore a delightful amount of fragrant blossoms and fruit, but lost many leaves as spring approached. "I guess I should have been more careful about watering them", I thought. During the summer, they got lots of rain, and hand-watering as needed, and they all put out fresh leaves, but just a few fruit. "I guess they're waiting for winter again", I thought. But I didn't get fruit last winter, and not only did they shed some leaves (though not as many), whole branches withered and died. "Maybe I'm giving them too much water this winter", I thought. Back on the deck this recent spring, they did not revive as before.

Then, I realized that the heavy summer rains of 2019 had probably leached a lot of nutrients out of them. Supporting evidence: algae was growing on the patio, using the lost nutrients. I hastily applied a few tablespoons of "citrus fertilizer" to each pot, and saw amazing responses from each within two weeks. Leaves, shoots, and then blossoms appeared.

Now, how could I prevent losing these nutrients again? I don't want to waste fertilizer, whether it's something that I buy or something that comes from the compost pile. What I've done is to salvage some corrugated plastic panels (formerly political campaign signs), cut them into disks that (mostly) cover the tops of the pots, and split sections of PVC pipe to protect the trunks. A locking cable-tie holds the two halves of the split pipe together, and also prevents the disk from lifting in the wind.

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ClareBroommaker's picture

Clever enough! You could also pick up that aluminum bin once in a while and rinse any soil that has collected right back into the pot with your rinse water.

The matte surface of your leaves surprises me. My citrus has shinier leaves, um, at least when it is healthy, which mine is not at the moment.

Also, the way your lower leaves on a branch are more yellowish than the upper leaves on the same branch, suggests that the older leaves are giving up nitrogen to the new growth. Is it a tad bit lacking in nitrogen? Nothing severe, I think. I think you'd still get fruit just fine, but if you can give it a bit more nitrogen it might help.

My tree is a mess right now. It has lost most of its soil from the pot and I've repeatedly found something better to do than to re-pot it. I tend to push my tree out to where it will get water falling from the porch awning-- rather the opposite of what you have done. And yes, that leads to algae growing on the limestone porch.

lathechuck's picture

Since the pot is covered, most of the water in the pan is straight rain-water. I'll scoop it out of the pan to water the tree as needed, but if I see mosquito larvae, it gets completely drained and dried. (Of course, there's always a little pass-through water from the regular watering, but not much. There may be other plants in the pan from time to time, to draw up excess water.

Those leaves are actually pretty glossy, but maybe the light was too flat (under clouds) to show the shine. The lower, yellower leaves are hold-overs from the time before fertilization, and I don't think they're going to get any greener with more fertilizer. It'll get fertilized again before winter.

The tiny white buds are opening today, and are being visited by a pair of butterflies (who I hope are pollinators)!

mountainmoma's picture

They should be transplanted into much larger pots with some new soil