Compost staying wet causing rot...What's the best medium for houseplants?

Hello,
So I recently acquired my first houseplants and I'm not having much luck so far.
The compost in all the pots just stays wet for weeks (all pots have drainage holes and a layer of gravel in the bottom, so they are not sitting in water). I'm not over-watering, I have only watered each plant ONCE since purchase after repotting into new pots and haven't needed to since. Needless to say I've been having problems with root rot.

I googled it and apparently this is a common problem when using stuff like Miracle Grow compost indoors. I've gone through a couple of bags of mult-purpose compost "suitable for pot plants" of various brands (Miracle Grow and Westlands) and they're not the "moisture control" kind, but they're obviously no good. I've lost two peace lillies in as many weeks and my Areca palm is showing signs of rot :(.

I've just bought a new peace lily, a couple of Boston Ferns, a maidenhair fern, and adopted a large but neglected weeping fig. I've had a ZZ, a dracena and a Mother In Law's tongue for about 3 weeks and so far they are still alive, but as the soil is remaining wet I fear it is only a matter of time! I repotted all the plants upon purchase with the aforementioned compost. (The only ones I haven't yet are an Ivy, the Areca palm and a Gerber Daisy!).

...So far this is proving to be very frustrating and expensive :(. I had no idea houseplants would be so difficult to take care of.

So, what on earth do I pot houseplants in?! I gather it needs to be aerated and well draining...I can't afford to keep replacing plants! I just want to get it right so I can relax and enjoy them.

Thanks for your advice!

 

If the pot is large, compared to the plant, or the amount of root that the plant has, then it will take the plant "longer" to drink the available water in the compost - and the compost will sit there, wet, during that time. So this is why it is best to pot on gradually into bigger pots as the plant grows (not saying this is your problem, but it might be worth you knowing )

Once a pot has too much water its quite difficult to get rid of it :( If you can get the rootball out of the pot without it all falling to bits (much easier if there roots are well developed in the pot, difficult soon after a plant is put into a bigger pot / new compost) then you can wrap the rootball in layers of newspaper to "wick" some water out.

An alternative is to put the plant outside (in partial shade if it is not used to full sun). The breeze etc. will cause the plant to drink more / transpire which will use up more water. Obviously that's no help in the depths of winter if its cold outside. You can bring them in for the night if the temperature will be lower than, say, 10C (some houseplants might want even warmer than that).

In terms of compost I mix 10% (by volume) Perlite with the multipurpose compost that I buy and I find that that keeps the compost "open" much better than anything else I have used. The "diatomic earth" (or whatever it is called) cat litter would probably do just as well (as you might not have any Perlite lying around!)

You said you have gravel? There are two places that I am imagining that could be:

1. In the bottom of the pot
2. In the saucer below the pot, and thus holding the pot clear of any water.

1 is bad :(, 2 is good

It seems somewhat illogical, but a layer of gravel in the bottom of a pot doesn't help the drainage. The transition from compost-to-gravel (and change of media) makes the water reluctant to move from the one to the other. Also the gravel will take up space in the pot which would be better occupied by compost which the roots can grow into and make use of.

Standing a pot on a saucer which has gravel/stones in it means that you can have 1/2" of water in the saucer without the pot sitting in it, and that water will evaporate and rise around the plant creating a more humid atmosphere which the plant will like. Also when you water the plant and excess can flow out into the saucer reservoir below.

Well .. they shouldn't be - unless you have something particularly fancy. I am somewhat surprised that you are having wet-compost problems at this time of the year, unless the plants are in a much larger pot than is suitable for them (or they are sitting in water, but doesn't sound like that could be possible)

 

Thanks Kristen.
Hmm I had suspected some of the pots may be too large in comparison to the root balls-I've read and been given very conflicting advice on that which has left me confused. It seems the plants I have require pots that look smaller than the main body/mass of the plant (which intuitively looks too small).

Yes there is gravel in the bottom of the pots :(. I was told to do this by several people but I have also read the opposite as you are advising! So should I remove the gravel from the bottom of the pots then?

I was wondering if there was something I could add to the compost I have in order to adjust it....However I have just read the following:

Quote taken from here.

Which suggests one shouldn't use store bought compost mixes at all, which makes thing all rather confusing and complicated!

*Maybe* I just need to take all of the plants out of the new ceramic pots I bought especially for them and put them back into the tiny plastic pots they came in (without a layer of gravel!).

Having said that-When I bought my third replacement peace lily (this time from a garden centre instead of Wilkos or a supermarket!), the soil it came in was absolutely soaking wet. Having bought one elsewhere that came with root rot, I made sure to check the roots of the plant before purchase. There was a table of very healthy looking peace lilys, yet nearly every single one had brown, mushy, stinking roots and white mold! There was only one that didn't (but was still saturated!). *So* even that particular garden centre was using an inappropriate medium or majorly over-watering.

The Areca palm I purchased from a different garden centre is still in the plastic pot it came in (so no gravel and the pot is not too big), but even that one seems to be suffering from rot. So while at this stage it seems logical to perhaps put all the other plants back into small plastic pots, I still wonder if there's a problem with the actual medium.

I am loathe to keep disturbing the plants and messing about with moving them from one pot to another without knowing for sure if that's the right thing to do, but at the same time if I do nothing I think I will lose more plants!

 

Or, can I perhaps add perlite and horticultural grit to the ceramic pots I have (as well as removing the gravel and re-situating it to the drip trays) and then not have to worry about the pots being too large? (So better drainage allowing more frequent proper watering). If so...How and how much? (I'm a total novice).

 

If that makes them top-heavy (large plant, small pot) then I stand the small-pot in a larger (preferably heavier!) pot and fill the gap between inner-and-outer with gravel. This adds enough weight to stop the thing falling over, and the plant looks right-sized for the pot.

I'd leave them be. Rectify that next time you pot them on / re-pot them.

yeah, "ask two gardeners and get three opinions"!!

I think Perlite improves drainage (but I use it more so that the compost retains less water, rather than drains better).

If you fill a pot full of Perlite it holds plenty of water. However, if I compare a plant in a pot filled with just multi purpose compost with an identical one with, say,10% perlite added then when I water them more water will flow through the perlite one (and out of the bottom) than the non-perlite one, so I think drainage is improved. Better not to give it too much water in the first place though.

yes, that sort of stance is of no help to a lay person is it? :(

I don't think you should have to add anything ... the compost you buy "should just work" (unless it is some really cheap rubbish, but the ones you have tried are good brands). But then I suppose every seasoned gardener will tell you of this-secret or that-trick ...

Multi purpose composts have changed over the last N years. Much less Peat being used, and a lot more other-stuff - council composted material, straw, and "rubbish" of one sort or another. Over that time I've found that adding Perlite has got me to where I want to be. But ... I would have expected houseplants to "just grow" in the sorts of composts that you say you bought. So we shouldn't entirely blame them, I think a combination of too big a pot / too much compost in the pot (for the plant's root size) andmaybe too much water (at least initially, maybe afterwards too even if you don't remember or think that was the case).

Seems a bit drastic! The ceramic pots do have decent drainage holes do they?

It is easier to gauge how wet the compost of a plant is in a plastic pot - pick it up and feel the weight (or stick it on the scales until you have developed the "feel" for the weight). With ceramic pots probably every one is a different weight, so its much harder to judge the weight by "feel". Standing a plastic pot'd plant IN a ceramic pot is another option.

I would suggest: fill an average-sized [plastic] pot with compost - straight out of the bag. Weight it (kitchen scales) and judge the feel of it. Water it, and then stand it in a bowl of water for 10 minutes, then let it drain (for another 10 say). Weight is again (and judge the feel). That's the difference between"dry" and "wet". You don't really want to get it THAT wet, and probably not quite that dry either. Unless the plant is of a type that wants to be "boggy" do not water it UNTIL it is close to being dry. Giving it a thorough watering, but only when the pot is getting dry, is much MUCH better than little-and-often. As the plant grows the watering interval will become shorter (the plant needs more) until you will get to the point where you are struggling to get enough water into the pot to last the plant through the day ... when that happens the plant is due (overdue in fact!) to be moved to a bigger pot.

Yes, good point, they may not have been well looked after before you got them :(

Try not to disturb the roots (impossible if you go from big-pot to little-pot, but in the other direction it should be possible)

Put some compost in the bottom of the new (bigger) pot. Stand the plant (with its existing small pot still on) in the new pot and make sure that it will be the right height - add / remove compost from the new pot until the test-height it right

Turn the plant upside down and knock the edge of the pot firmly on the table so that the plant falls out of the pot (have the plant between the fingers of your hand so that it only falls an inch or so, and into your hand). Turn it up the right way, place it into the new pot, and put some compost in the gap around the outside of the root ball. "drop" the new pot onto the table a couple of times, briskly, to settle the compost. That's it. I never compress the compost around the rootball - it will compact by itself just through watering over the coming weeks / months and I want it open / airy so it is easy for the roots to grow into it.

 

Thanks Kristen . I think from now on I will add perlite in with ready-mixed compost instead of using it as it is. I decided to add some to the Peace Lily, ZZ, Snake Plant and Weeping Fig pots (they don't seem to be upset by the disturbance as the roots haven't had enough time to grow out of their original ball yet into the rest of the soil). Left the ferns for now since they like to stay more moist and two of them are in terracotta pots, which I have learned dry out faster anyway! So I'll see what happens!

I decided to get some houseplant books from the library, funnily enough they all say to put gravel (or some other drainage material) in the bottom of the pots first! So yes it seems every gardener has a different opinion on that one! .

 

Widely repeated advice. I haven't tried it side-by-side but the academics say that it was proved over 100 years ago that this was a bad idea (contrary to what would seem logical)

I'd like to get hold of an academic to ask them some ancillary questions before I am convinced.

Dr Linda Chalker-Scott (academic in a horticultural department in an American university) is probably the most widely quoted source for debunking of these sorts of myths:
http://www.sustainable-gardening.com/how-to/tips/drainage-in-containers

However, she bangs her drum quite loudly and I'd really like to find a way to ask her my ancillary questions. Worth a read of her myth-debunking to at least open your mind to the fact that some traditionally assumed / followed maxims may not be all they are cracked up to be! Here's some links:
http://puyallup.wsu.edu/~Linda Chalker-Scott/Horticultural Myths_files/index.html

I own her book "The Informed Gardener" and its a good read. But it raises unanswered questions in my mind ...

 

Oh wow, that could well be part of the problem then! Thanks for those links, that's amazing! I'll be sure not to include gravel the next time I pot up/repot plants! I'll check out that book too .

 

Kristens advice is good Jen but I've just picked up on your quote above which rung a few alarm bells! Were the plants pot bound? In other words are the roots all in a tight ball? That could be part of your problem. If they are then you need to tease all the roots apart so they are free to grow into the soil. Don't worry if some break away, as long as the plants have roots attached they will grow, they will also produce more roots over time.