Adenium Obesum Desert Rose/ Cactus Rose

I have a Cactus Rose plant for years. When we had it at our business in a southern facing window, it bloomed many times a year. When we had to close the business I brought it to our house and put it in a southern facing window but it has not done well since. If it tries to bloom, the blooms fall off before opening. This year I put it outside during the summer and it seemed much happier and gained a lot of leaves. It again tried to bloom but the blooms fell off. I brought it back inside because the weather is getting too cold at night and all the leaves promptly fell off. It is growing new leaves but I was just wanting some opinions as to what would make this plant happy in my house! Thanks!

I am no expert, but I do have one of these. I don't know for sure of course, but I have one in a sunny window. If it gets too dry while the buds are forming they turn brown and shrivel up right away. They also need a fair amount of fertilizer. I found mine had grown a big caudex (root tuber) that was filling up the pot, so as it had grown there was less and less soil in the pot for the water, it really liked being repotted into a bigger home. I took the opportunity to raise it up a bit, so I could admire the caudex.

Difference in lighting and humidity prob.

I just brought mine in a few weeks ago, and it dropped a lot of leaves. They do that when you first bring them in. I think the sudden change in temperature, humidity, and light shocks them. I read a while ago that low boron could lead to flower drop. It's possible that your plant is just ready to be replanted with fresh soil. The fact that yours is trying to flower means that it's still reasonably healthy, but it may have a nutrient deficiency.

That said, mine does not flower indoors (probably not enough light in my apartment). I kept it inside for a year and never got a bloom, then put it outside the next summer and got some flowers.

We are talking about Adeniums (desert rose), right?

They need full sun. And it may be all about the windows, how new they are and how much and which UV rays they are blocking. Also, are there trees outside blocking some of the sun? Its obvious your plant was happier outside; for some reason, the quality of light is different inside your house.

In the summer, Adeniums need regular water. In the winter, stop watering altogether.

Humidity is a non-issue as these plants just don't care. Fertilize while they are actively growing. Use a balanced fertilizer (like 20-20-20 plus micronutrients) at half strength every time you water.

Thanks so much for all the responses!

A word of caution. The ONLY way you can use half strength 20-20-20 at every watering is if you're thoroughly flushing the soil every time you water (or at least very regularly and very frequently). If you're NOT flushing the soil when you water, the soils EC/TDS level (roughly, the level of dissolved solids in the soil solution) will very quickly become so high it will actually reverse the osmotic process (by which the plant absorbs water) and pull water OUT of plant cells. This reverse process is called plasmolysis, but we commonly refer to it as fertilizer burn.

It's still not clear what plant we're actually discussing, unless I missed the ID? There are several factors that might be causing blooms to abort. Nutritional issues (especially skewed nutrient ratios), root congestion, over-watering, under-watering, a high level of dissolved solids in the soil solution, thrips, ..... How serious are you about rehabbing the plant?

Al

A photo would be good so we could be sure we were all talking about the same plant.

Most Adenium growers use time-release fertilizer plus a liquid fertilizer with micronutrients. I err on the side of caution and skip the time-release and cut down on the strength of the liquid fertilizer. I think the biggest concern would be shocking the plant with a sudden dose of full strength fertilizer, not the buildup of salts in the soil.

The biggest concern when fertilizing at half strength every time we water definitely is the level of dissolved solids in the soil (salt build-up), and you can't "shock" the plant with a full strength dose (according to the package directions) of fertilizer unless there is already an existent build-up of dissolved solids in the soil. Plants use only tiny amounts of fertilizer, so we can't depend on the plant to significantly decrease the level of dissolved solids (fertilizer salts) in the soil. If you aren't flushing the soil, where does that half strength dose of 20-20-20 go? Nowhere - it stays in the soil; so, after 2 applications w/o flushing the soil, you now have a full strength dose of salts in the soil. At the third application, you have 1.5X the recommended dose and the plant is having difficulty absorbing water. After 4 applications, there is 2X the recommended dose of fertilizer salts in the soil solution and the plant is likely experiencing severe symptoms. All the above is why using half strength applications at every watering isn't possible (for very long) unless the grower is consistently flushing the soil at ach watering or at a minimum, every other watering.

Also, using 20-20-20 or any other fertilizer that doesn't closely mimic the ratio at which the plant actually USES the nutrients w/o flushing the soil ensures that the ratio of nutrients in the soil will quickly become badly skewed, which is very likely to result in antagonistic deficiencies, in addition to the high EC/TDS (salt levels) caused by frequent fertilizing w/o flushing the soil - a double whammy, so to speak. On average, plants use about 6X as much N as P. Based on that fact, 20-20-20 supplies more than 2.5X as much P as the plant can use. That excess P messes with alotta stuff. It raises soil pH, unnecessarily raises the EC/TDS of the soil solution with no upside, and it competes for attachment sites, it causes antagonistic deficiencies of several nutrients (but mostly Fe [iron]).

Al

Oops! Just missed your post, Al. Evidently we were thinking along similar lines.... :)

Some quick math here. The result surprised me. Say I am running 1/4 strength fertilizer at every watering, and flushing with about 1/4 the total volume (ie. this is the amount of water that runs out the bottom every time). These numbers are somewhat arbitrary but based on my own plants, as a real-life example.

The second time I water (which is when the soil is mostly dry), the media will absorb a nearly equal volume of water (plus fert), effectively doubling the total salt strength it contains. This assuming the plant does not consume any nutrients, for simplicity. After the flush what remains is 1.75x the original. Keep this cycle going indefinitely and you arrive at a stable salt concentration 4x the original, which is to say full strength fertilizer, not the intended dose. That's where equilibrium lies in the long term even with continual, carefully controlled flushing.

This message was edited Nov 19, 2015 2:31 PM

So how often do you guys flush a potted adenium?
I am assuming that if I put my potted adenium in the sink, and overwater it three or four times so the water is just running out the bottom, this should do it. And do you just just tap water, or a mild solution of fertilizer so as not to "shock" the plant with a big sudden change in osmotic pressure?
Thank you so much, I learn so much from y'all.

I flush and fertilize every time I water with a very low dose of FP 9-3-6 (in the winter). I do this because it is the best way to achieve my nutritional supplementation goal, which can be described as ensuring that all the nutrients plants normally secure from the soil are in the soil solution at all times, in the ratio at which the plant actually uses the nutrients, and at a concentration high enough to ensure no deficiencies yet low enough to ensure the plant isn't impeded in its ability to take up water and the nutrients dissolved in water. It would follow that someone disagreeing with that description should be able to redefine the goal and then provide a method of achieving same. You can see it's a worthy goal that really can't be met by using 20-20-20 fertilizer or by fertigating with a half (mfg's suggested rate) solution of fertilizer at each watering (unless you DO flush the soil).

When I water (in winter - because that's when the plant's are indoors), I apply enough water so 15-20% of the total volume of water applied exits the drain. Each time I water/fertigate, I'm using a solution of 1/4 tsp of Foliage-Pro 9-3-6 in a gallon of R/O water.

Everywhere you look, you'll repetitiously hear the advice to withhold fertilizer for houseplants in the winter, But that advice is based on an assumption and is designed for only one thing - to protect you from yourself. The assumption is that you'll be using a water-retentive medium which doesn't ALLOW you to water copiously enough that you're flushing the soil when you water, for the fear of root rot and impediment to root function. The 'protect you from yourself' thing also centers on the assumption you'll be using a water-retentive medium and will not be flushing the soil. The assumption is, it's better to avoid fertilizing altogether and risk the consequences of that, than to flush the soil and open yourself to the impact of impaired root function/health due to extended periods of sogginess; so you're presented with 2 choices, neither of which is good. Using an appropriate medium can eliminate (practically speaking) BOTH issues - over-watering and a build-up of salts in 1 fell swoop.

Anytime you hear the advice to withhold fertilizer in the winter (for houseplants) w/o several qualifications, whoever gives the advice probably can't explain why it's given. Does Mother Nature pull all the nutrients out of the soil in the winter for the plants she tends? NO.

You certainly don't want houseplants to have a soil solution with a high EC/TDS (salt level) in the winter, but there is nothing but good to come from maintaining a low level of nutrients in the soil at all times. In fact, it's a requirement if plants aren't to be limited by high EC/TDS and skewed nutrient ratios.

Al

This message was edited Nov 19, 2015 7:42 PM

My own practice is more or less as described above. The key (under my regimen) is to make sure water exits the bottom every time, and to avoid "topping off" where that does not happen.

A few thoughts.

Most commercial soil is peat-based and behaves a bit problematically when it dries out, especially when it goes bone dry. The issue is that the fiber needs to be moist in order to efficiently absorb water. So if you water too much up front, the excess streams right through without fully wetting the soil. Better to water in two or more separate rounds (again my regimen) such that no water comes out the first time, and water always comes out the second time, or last time. This is not a big thing with Adeniums, as they do not really like to go fully dry when they are in active growth.

If your container is unglazed clay then you need to take the whole salt buildup thing more seriously. The container itself (especially in larger sizes) has the capacity to hold water, making any flush less effective in comparison. And because the water will evaporate through the clay all around the pot, it will leave salt buildup at its exit points, and this can get ugly.

Rain is the best flush of all, and congratulations if you're raising your Adenium in a climate with summer rainfall. Any proper rainstorm taking place over a few hours will flush a lot of salt. When it rains here (mostly in winter) the plants always look better, and some of the effect may have to do with more than just the above-ground scrubbing.

I agree with Al. Winter dormancy is one thing, but most plants kept indoors at human temperatures during the winter will continue to grow as normal. The key is to remember that the light is lower and more southerly (in the Northern Hemisphere) during winter, and put plants in a position where they will not suffer from those changes. We have a very mild climate and I do not vary the nutrients except when plants actually go to sleep (as Adeniums are prone to do).

Finally you also have to consider the effects of dissolved salts in the tap water itself, especially hard water from groundwater, especially (like ours is currently) being pumped under drought conditions. The salt in the water, before you do any tinkering, can be substantial. It will build up in exactly the same way as the fertilizer salts, and lead to the same white stains on clay pots.

Thanks, you two have been extremely helpful, this is just the kind of advice I was hoping for. I think I will find a source for Foliage-Pro too.
Baja, thanks for reminding me about the clay-I do have some houseplants in unglazed clay. Unlike some folks in hotter climates, here it is often very cool. I have found some indoor succulents do better in clay, if I put them in plastic pots it is easier for them to drown in winter. My adenium seems to like the unglazed clay. Now on the other hand thick clay glazed on the outside seems to drown my houseplants (as you say the clay absorbs water, maybe that is the problem), or keep them too cold or something-I ran into a sale of outdoor glazed clay pots a few years ago, they don't seem to work well indoors.
I have plants I can't put in the sink, like hanging plants or big ones. I have a turkey baster and a baby's bulb syringe (1$ Store) that I use to suck the extra water from the saucer under the plants, so they don't sit with "wet feet".

My mistake was assuming that TNBEE was running a lot of water through the pots when watering/fertilizing. I don't think I own a saucer so the thought never entered my mind that someone might be letting the water sit in a saucer to be re-absorbed by the plant.

If your Adeniums are in saucers, pay attention to tapla and Baja. But this will be true for any plant.

Daisy

That's funny, I don't use saucers for any of my outdoor plants. The saucer is a separate issue from the salt buildup, in my mind. There are various tricks you can use, like grouping smaller pots on a baking tray or similar type of easily portable wire grid, in order to avoid forcing plants to sit in water. i like to drop a thick towel and water my indoor plants on top of that before returning them to their spots.

One trick that works great to get water out of saucers (especially when they are outside on a floor that can get wet) is to take an old rag or wash cloth and tuck one end into the bottom of the water-filled saucer, the other flat onto the ground underneath. By capillary action and the force of gravity (no human effort required beyond this point) the water will pass through the towel to the floor, exiting the saucer completely in an hour or two (or whenever you have forgotten about it).

Clay pots work great for my indoor succulents. I like the fact that they allow the whole mix to dry out every time guaranteed, after a couple of weeks of sitting in indoor sun anyway.

My assumption above relating to the flush was that including fertilizer with every watering means there is a cost incurred for the run-through, which is the cost of extra fertilizer above and beyond the minimum required, thus a disincentive to flush. My compromise in that regard is the 25% mentioned above, set your own as you see fit and can afford. :)