help! My gardenia's tips are starting to turn brown

I'm new to houseplants & have taken on quite an endeavor! My gardenia's leaf tips are starting to turn brown. I check the soil religiously for moisture content, feed every other week with Miracid, it sits under a blue & red led grow light all day, the temp in my house is around 72 & the humidity averages @ about 65% so I keep it on some rocks on a tray with water. I have a vaporizor below it that uns 24/7. When I switched methods of heating the temp dropped down to about 65 & I usually have the grow light on for for all day. What do you suppose is going on? It is otherwise healthy & is getting ready to give me it's first flower! Oh & for the record, I'm not crazy. I have several other houseplants & an indoor greenhouse. Thus the climate control.

If you're not over-watering, you probably have developed a high concentration of soluble salts in the soil. If you're fertilizing at suggested strengths and not flushing the soil every time you water, there is little question you're over-fertilizing.

Al

Thank you! I just checked the soil this morning & it was pretty soggy. I think somehow they are sucking up the water from the tray. The night blooming jasmine's soil is just as soggy & they sit next to each other. Maybe if I add more rocks & make the mound they sit on a little higher up? So how do I test for salt content, or is there such a test? The jasmine's leaves are fine, as is their tray mate an african violet.

You need to do something to ensure the effluent in the collection saucer can never find it's way back into the soil once it's exited the soil. There ARE ways to measure the EC/TDS of the soil solution, but if you abandon practices that guarantee a build-up of solubles (like watering in small sips instead of flushing the soil) it won't be an issue. The problems we're discussing - excess water retention, lack of aeration, poor drainage, compaction, a high level of salts in the soil ..... can all be avoided by simply adopting an appropriate soil - one that allows you to water correctly w/o having to worry about the soil remaining soggy for an excessively long time. Let me know if you have more questions, or if you think there might be anything else I can help with.

Al

Oh yes please! Right now I have a bag of organic potting soil, a bag of perlite, & one of peat moss. Would any combination of these work? If so @ what ratios? If not what would you recommend? Also would it be something I could use for my other plants? I've mentioned the jasmine & african violet but I also have a dwarf meyer lemon that could use a transplant also. I also am germinating several different seeds & so far have a baby passionflower. Is there something that could benefit all of these guys?

When I caught the bonsai bug some 20+ years ago, I discovered I couldn't keep my trees alive in shallow containers because the soils I was using were working against me. Once I switched to soils made of larger particles, it was like throwing a switch - everything got easier. Mixing fine ingredients with more fine ingredients + a soil made of fine ingredients = excessive water retention. Adding perlite to peat/compost-based soils reduces o/a water retention, but doesn't appreciably help with aeration, drainage, or to reduce the ht of the perched water table unless the particles are large enough and you've added enough perlite - somewhere in the 70-80% range.

Imagine a quart of sand with a pint of BBs mixed in. Do the BBs improve aeration/drainage/ht of the PWT? No, they don't. Now, start subtracting sand. At what point do we reach the threshold where the BBs start to do some good? The answer is, when there is not enough sand to fill the spaces between the BBs. The same id true with peat or compost based soils and perlite. It doesn't help notably with aeration or drainage until there is so much perlite the finer ingredients cannot fill the spaces between the perlite particles.

The KEY is to avoid starting with a large volume of fine particles, and trying to AMEND them with large particles. It does very little good to add a small fraction of perlite or pine bark to peat or compost ..... but if you START with a large volume of pine bark or other coarse ingredients - you already have, built into the soil, excellent drainage/aeration, and a PWT reduced in height or absent altogether.

The answer to your question is, you CAN build a decent soil out of the 3 ingredients mentioned, but it would have to include a very large fraction of coarse perlite ..... and it would be less expensive and almost certainly better for the plants if you relied on pine bark as the base for your soil instead of perlite or one of the other commonly used fine ingredients already mentioned.

If you can make the time, you might find some value in the sticky thread at the top of this forum.

If you would like to learn more about how water behaves in soils: http://davesgarden.com/community/forums/t/1073399/

Al

Cool! Thank you! This is valuable information. I've been having a lot of problems with soil actually & didn't know exactly what was even wrong. But now I understand. I live walking distance from Home Depot (convenient since I don't drive) hopefully they'll have a small enough bag to lug home on my own. :-)

P.s. from what I understand I'll need it anyways for my orchids when they germinate!

Hi Al, I have a problem with my variegated split leaf Philodendron. The tips are turning brown. Ok, it sounds like, from your sticky, that I watered it too much. I cannot tell, if the soil in the bottom of the pot is wet, sounds like it. So, should I repot it now? Give it some new soil? It is really difficult for me to get the things you use, but I can get grit that chickens use, and I have some coir blocks with fairly large bark (solid pieces) and then maybe perlite, and peat. So, what should I use? If you think I should now. We still have a couple feet of snow on the ground. Difficult to get around and far from shopping.

One other is a variegated Clivia. It finally got a new leaf in 2 years. Are they just naturally slow growing, or is there a problem with something I am doing?

Thanks so much for your help. It has been a long time since I have needed your help. Jeanette

You should be able to find fir bark in abundance where you are, and if you live close to Spokane, Turface MVP is also available - or you could substitute screened NAPA Floor Dry for the Turface. There are a number of issues associated with using coir of CHCs as a primary fraction of a soil, so I would try to stay clear of that product.

Study: http://www.usu.edu/cpl/PDF/CoconutCoirPaper.pdf

If you'd like, I'll post something I wrote about coir and CHCs that pretty much agrees with the study results.

What city/town do you live in/near. Maybe I can help more.

I've learned from the thousands of growers I've communicated with in all types of venues, that for most, the largest step forward they can make as container gardeners is by gaining an understanding of how to make their soils work FOR them, instead of against them.

Al

Thanks so much Al. Glad to have any info you can give us. On the coir. Several of us do use it so really need to know.

Spokane is the nearest city, a hundred miles away. But, I do have to go down there in the next couple weeks for an eye appt. So whatever you can give me will be very much appreciated.

I hear what you are saying about fir bark being available here, but in what form,and under what name? Thanks,