Gardenia troubles

I am not having good luck with gardenias. I see them growing in my area, thriving without much attention at all. I bought one this spring and all the leaves turned yellow, fell off, and it died.

I bought another this fall, planted it in a different location about 2 weeks ago. The leaves are turning yellow and starting to fall off.

For both plantings, I dug very large (2 feet across) holes, and amended with peat, humus, rotted manure. My soil is a sandy loam. The first location was morning to midday sun (east side of house) and the second location is on the north side, with filtered partial sun all day long. None of my other plantings have reacted this way. Just the gardenias. Are they just finicky?

How much are you watering them?

It could be either too much water or not enough. I have 3 large bushes and 2 are doing what you described. You may have heard that the Atlanta area is in a critical 100 year drought, so my bet is not enough water.
Mine are about 20 years old and I don't give them much attention except to prune them back every year after they have bloomed.

I'm watering 2-3 times a week.

The one I planted earlier in the year did not survive.

The more recently planted one is hanging on for now. Only about the lower 1/3 of the leaves have yellowed.

I cut back the top 1/3 of the stems when I planted it, hoping to help it grow roots.

I think that you are overwatering it-thats a lot to be watering it once it is in the ground. Roots grow better in dry soil, then wet because they need oxygen to grow and water displaces oxygen-so they cant breath if the soil is always wet, and the roots start to rot, and then the plant turns yellow.

Azalea-thankfully, my gards (about 20yrs old too) are doing fine without water-we are in the same awful drought you guys are in. They say Raleigh will be out of water in early Jan if it doesnt start to rain soon. I have about 20 together and I haven't watered them all summer. We need rain so badly-I hope we all get it soon.

I would guess your gardenias need some iron and not so much water.

All of the above too. Yellow leaves in Gardenias is a symptom of some sort of plant stress but unfortunately, many things can cause yellowing so you need to see which one applies in your case.

1. Overwatering & underwatering gardenias are probably the most common causes for yellow leaves. I suggest you do not water three times a week but instead water only when soil moisture is needed. Try this approach daily: insert a finger into the soil to a depth of 3-4" and determine how the soil feels down there. If it feels moist, do not water. If it feels dry or almost dry, water. If it feels wet, determine if you have a drainage issue. Do this daily for about two weeks until you notice a watering frequency developing, i.e., you notice yourself watering every three/four/five/etc days. At that time you can set an automated system to water on that same frequency. For a brand new plant in a 3g pot, make the sprinkler provide 1 gallon of water every time it waters. Then check daily in this manner again if the temperatures change 10-15 degrees and stay there. Keep the plant well mulched; about 3-4 inches of acidic mulch is adequate.

2. Poor drainage is another reason for yellow leaves. With poor drainage, the gardenia's roots could sit on wet soil for too long and develop fungal problems like root rot. As a result of that, the roots cannot provide enough water to the plant above and the plant responds by dropping leaves. Gardenias should be planted on well draining soil. Your sandy soil may require more water than usual. To test drainage, dig a hole 6 inches deep in the bed and fill it with water. If the water has not drained from the hole in four hours, you have poor drainage. If it drains from the hole is much less than four hours, your drainage is "too good". Solutions for clay and sandy soils: (a) plant using raised beds, (b) install drainage tile to carry away the excess water, (c) ammend your soil with compost and well draining acidic soil or (d) any combination of the above.

3. Mineral defficiencies -specially iron- can also cause yellowing of leaves. They are easy to detect though. The leaves turn light green or yellow but the leaf veins remain dark green. The cause of this condition varies but the bottom line is that the soil alkalinity increases and the gardenia cannot absorb iron from the soil. Adding liquid acidifier products with chelated iron compounds is one solution here in Texas. Another solution is to reduce the alkalinity by ammending the soil once or twice a year with products such as Elemental Sulphur, Soil Sulphur, Espoma's Garden Sulphur or Green Light Iron Soil Acidifier. These last three do not contain any nitrogen (their NPK Ratio is 0-0-0) in case you need to apply them during winter.

A local nursery should be able to tell you if you need to ammend the soil where you live. Cheap kits that measure soil acidity/alkalinity are also readily available in most nurseries; these kits can be used often (each kit is good for one or two tests but you can buy/use another kit anytime). The test results are approximations only. A test soil is the most accurate way to measure your soil alkalinity; a soil is recommended once every 3-5 years though.

4. Miscellaneous issues... Nematodes and diseases can also cause yellow leaves but here in Texas we do not have much of a nematode problem; I doubt this is an issue for you. Tip burn, which occurs particularly at vein terminals, also causes the leaves to lose their color and die. Low soil temperatures (below 70 degrees) can also induce yellowing. Plants in too much shade can also exhibit syptoms of yellowing leaves. Over-fertilizing can also cause yellow leaves; newly planted gardenias already contain fertilizer in their pots so do not start fertilizing until next year; note: since your plant is stressed, do not add any fertlizers or ammendments until the cause is identified. Finally, yellowing is normal during winter or before new growth appears in evergreens like gardenias.

Does this help you, LauraHarber?
Luis

Hi Luis and everyone who responded,
Thank you for your terrific help.
I have slowed down on the watering, the gardenia is in a slightly raised bed on a gentle slope.
The yellowing seems to have stopped, or at least it is not getting any worse right now.
I don't think the problem is iron at this time, but I would like to ask a question about iron.
Our region has iron ore rocks and areas of red clay. I do not have any exposed red clay but we have excavated several of the rocks from our property. Do these contribute iron to the soil naturally or indicate the presence of iron in the soil?

Iron is one of most common naturally occuring elements and originates from iron ore. Pure iron looks grayish white and suffers a lot from rust if not protected by processes like galvanizing, etc. You can have a soil test done by your Agriculture Extension Service if you are concerned by levels of iron in your area. Red clay usually has lots of iron oxides. Iron, unhydrated iron oxides, manganese dioxide and partially hydrated iron usually contribute to the red color you see in the soil.

thanks, luis,

This leads me to believe that there may not be an issue with iron, as it does occur freely in our region and is dispersed into the soil.

There are threads of it in my soil beneath the surface, but fortunately, my yard is mostly a sandy loam with only bits of the red clay.

As of today, the progression of yellowing leaves has stopped, and although I do not see any new growth coming on yet, it does appear to have stabilized for now. It rained bunches 2 days ago but it seems to be doing well!

If your soil pH is too high, even if there's oodles of iron in the soil the plants can't take it up. If that's the case, what you have to do is bring the pH down to make the soil slightly acidic, then the plant will be able to take up the iron that's already there.