I have a considerable amount of experience growing and manipulating a wide variety of woody plants in containers, and am very familiar with the nutritional needs of plants and the way elements interact in the soil solution, but first please share a few of your questions and tell me why you think Epsom salts is likely to help your plant; I'll share my thoughts and any answers I can help with.
I grow and sell gardenias and I ask this question early in the month, hoping someone would enlighten me regarding potted plants and epsom salts. Since then I went to All Things Plants, ask the same question and got the answers immediately. I thank you very much Tapla for your kindness and helpfulness but I no longer have any questions. I am very disappointed that Dave's Garden is getting so quiet. There was a time when you ask a question you got an answer before you changed threads. I guess people move on.
Have a nice day and thanks so much for your offer to help me.
The question in my mind is ... did you get accurate information? Generally speaking, applying magnesium A) when it is already in the soil in adequate amounts, B) w/o supplying a proportional amount of Ca to eliminate the possibility of an antagonistic deficiency C) when it is not the most deficient element, are all limiting practices. Applying Mg is only a benifit when Mg is THE most deficient nutrient.
There is only 1 'ideal' ratio of the essential elements to each other and 1 'ideal' o/a nutrient level (EC/TDS). Anything in the soil solution in excess of either of these ideal levels is limiting; so 'a little extra Mg' in the soil solution isn't a good thing.
In view of what you're growing, if you're using gypsum instead of dolomite as a Ca source to help keep the media pH down, you could make a case for applying Epsom salts in very small amounts on a regular basis, but if you're using dolomite to adjust your media pH and as a Ca/Mg source, it's unlikely that you'll need to supplement Mg until near the end of the second year in the same soil (the Mg fraction of dolomite is about 125X more soluble than the Mg fraction); and I'm assuming that if you're trying to maximize growth, you're bumping the plants to a larger container BEFORE the root mass and soil can be lifted from the original container intact. This means more (fresh soil and a fresh infusion of Mg in the dolomite, if you're using dolomite or it's included in the medium), so supplementing with Epsom salts would in all probability be unnecessary and a limiting factor.
Hello Al, You are so kind to want to be sure I got the correct information. According to what you have said and what Horseshoe told me, I think I am on the right track. I do appreciate your help. In fact, I am going to print out your post and keep it so I remember what you said. I am 83 and sometimes it is best I write things down. Thanks again. JB
Al, can you tell me a little about how to keep a Christmas cactus healthy. Mine has bloomed beautifully for about 4 years but did not bloom this year. I believe it is root bound and water disappears very quickly. I found out it grows on trees in the tropics so ruled out using sand in the potting mix. I have some Bacto potting mix that I thought of using. Other keeping it watered, I try to use a little MG on it from time to time
I am a big believer in Black Kow (composted cow manure) and Black Hen which is uncomposted chicken manure but I use it with great discretion.
Can you tell me what you think of the soil mix and what I should use for fertilizer and how often.
I looked at the ingredients in the Baccto soil. It's made from reed/sedge peat, sand, and perlite. Reed/sedge peat is the muck that forms when reeds & sedges die in the shallow water of ponds & lakes. The muck is raked up, allowed to dry somewhat, and then packaged. It's in an advanced state of decomposition already, when it's first mined. The sand doesn't offer much encouragement either. I don't see how it could NOT be an extremely water-retentive soil and probably not a good choice for epiphytes. I would choose something chunky, like the soils I use or one based on large particles - like pine bark. The plant wants excellent drainage & aeration. The gritty mix would probably be ideal.
I'm sorry, but I'm not much of a believer in manures in container media. I prefer to have more precise control over what nutrients the plant is getting, and when - easiest to achieve with soluble fertilizers. Also, manures break down quickly, clogging soil pores while not offering anything but duplication of the nutrients in the fertilizer you're using.
Christmas cactus is one of the few plants I would use a 1:1:1 ratio fertilizer on. HOW you fertilize depends on your soil choice & watering habits. Assuming you adopt a fast-draining, well-aerated soil, I would fertilize every 2 weeks while the plant is in its growth phase with a weak dose (half the rate recommended for houseplants) of Dyna-Gro's 7-7-7 All-Pro Plant Food, right up until the time of bud formation, then stop until blooming is complete. If you don't want to order the 7-7-7, use any of the commonly available 20-20-20 soluble fertilizers (half strength). I like the Dyna-Gro because it gets it's N from ammoniacal and nitrate sources instead of urea, the source most other soluble fertilizers use.
No, not disappointed but I have already done it with the Bacto, some Black Kow and some bone meal. I left out the sand and moved it to a shadier area.
The roots weren't soil-bound and I had room in the pot, so I just added my mix to the bottom, settled the plant back in and then added some of my mix to the top.