Basically, you're doing a lot of over-thinking.

The basics of plant disease are the 3 factors contained in the Disease Triangle -- you might research that phrase.

The factors are:
1. susceptible host (the [plant)
2. the disease organism
3. Environmental conditions (those well suited to the disease organism)

In order for disease to occur, all 3 items must be present at the same time.

If it rains every day, and the pot has drain holes and has been filled with potting mix. roots will be fine.

If it rains several days, and you don't have standing water in the garden, roots will be fine.

The risk is when you have poorly drained soil and have installed plants susceptible to root rot organisms. Then you're taking risks which will eventually cause problems when the correct temps occur -- as in the Disease Triangle..

If a soil-borne organism lacks airborne spores, that is not necessarily a good thing. No way to get rid of it. But you can avoid the root rot by NEVER planting a susceptible plant -- that's the Disease Triangle.

Pythium is a disease that relies on conditions of saturated soil and elevated temps.

Phytophthora is a disease that relies on conditions of saturated soil and moderate temps.

This post was edited by jean001a on Thu, May 29, 14 at 23:06

Overthinking is being very kind. Whatever happened to just simple gardening!

As a rule commercial potting mixes are put together to promote drainage and not create conditions that would promote root rot. The potting soil would need to be quite wet for weeks before root rot would set in. Plants do need an evenly moist soil because they cannot uptake necessary nutrients without moisture.

Thanks.

I wonder though if we have different potting mixes in our countries. 10% of Sweden is covered by peat, that's probably one reason why all ordinary potting mixes for houseplants have 90-95% peat. Not very well draining unless you yourself add grit/small pebbles/bark mulch etc. I can imagine a Ponytail Palm (or other plant that doesn't drink much) can remain wet for at least a week if not two if there's not much sun.

But as long as being wet two weeks is fine, it would be ok.

BTW I hear here all the time that it is much more common that plants die from over- than underwatering. Is it not the same in the US?

You wrote:
"I simply asked for your experience in how many days of wet soil you may have without risk for root rot for a healthy indoor plant."

No answer to that question.
As you've already pointed out, the answer lies in the environmental conditions best for the plant's health.
You wrote:
"I hear here all the time that it is much more common that plants die from over- than underwatering. Is it not the same in the US?"

Most people define overwatering as watering too often, perhaps daily. In those conditions, the plant could be underwatered -- i.e. too dry. I've seen it many times.

Instead, the definition of overwatering is excessively moist soil/media.

2/3 peat and 1/3 grit is not a particularly well-draining medium. If you want to explore the topic further, I suggest you hop over to the Container Gardening forum. They seem to like over-thinking over there.

Dennis

If one is questioning how long it takes for plant disease to take hold, one must also realize poor draining mixes apparently widely used in Sweden will only encourage such disease. In other words, this issue is being looked at from the wrong end. Give yourself a proper draining soil and you will be able to give your friends an idea of when your plants need water and that need will be consisent. To use a poor mix and wonder how long it will hold out? Why make it a guessing game if you don't have to?

I'm basically asking for experiences how long a plant can have wet soil without getting root rot. Should be easy enough to answer, don't know why you can't seem to do that.

Changing soil of a palm tree is a bad idea. And just because the mix isn't the same as what you prefer, it doesn't mean it is bad. E g the 2/3 peat based potting mix plus 1/3 grit size 1/10" I was told was a good choice by a guy who runs a nursery in Thailand filled with just rare palms (but this can vary a bit depending on palm).

This post was edited by David_Sweden on Wed, Jun 4, 14 at 11:25

When I ask about "potting soil in Sweden" in the search engines I get a lot of nonsense answers but not one about the question. As best I can answer would be that potting soils sold in Sweden should have either perlite or vermiculite mixed in with the peat to promote drainage, people I write to in Ireland, Germany, and France tell me potting soils sold there do.
When working on our local plant problem call desk at our local MSU Cooperative Extension Service office, as part of being a Master Gardener and an Advanced Master Gardener, a very common problem was overwatered plants. While somewhat difficult with commercial potting "soils" it can be done although sometimes we had plants brought in with garden soil in the pot. In some 50 years of gardening and growing things in containers outside using either commercial potting soil or my compost I have not had a problem with those containers holding too much water and the plants getting root rot, except if the pot was put into something that might hold water such as a 5 gallon bucket.

I didn't answer because I can't answer. A) this is my first year having a garden and B) I would rather have a healthy plant than over water and guess when one might dry out. That is the point that David_Sweden seems to forget, regardless of reasons for asking. No reason to get snippy about it.

I may be new but I very carefully selected 1/3 compost, 1/3 peat, and 1/3 vermiculite as an example. Why? Because I have native clay soils that may not drain for weeks after a hard rain. It has nothing to do with what I prefer. I simply want healthy plants.

It is nice to see kimmsr confirming overwatering is a very common problem. Obviously several people here have a lot to learn.

If you search for overwatering on Swedish sites using the Swedish word (övervattning) you will get lots of hits, one being this official page on the probably biggest gardening site, with a top 7 list of reasons why newly bought plants soon wilt at home. Overwatering is number 1 on the list.

But I'm not sure when root rot kicks in, you get a few other symptoms before that, and you can also get stem rot, which is probably even worse for the plant, so I should add that to the topic (any kind of rot or permanen damage).

Since more than one person here seems so convinced overwatering (meaning: keeping the soil very wet for many days) is not a common problem, I took a look at soil contents in Sweden and the US.

Houseplant soils in Sweden

Here you have a major Swedish soil company, who state plainly the contents for all their houseplant soils:

• Sowing soil, for seeds (sÃÂ¥jord): 90% peat, 10% fine sand
• Elite Potting Soil (Elit Blomjord): 87% peat, 7% sand, 6% leca 2-6mm
• Potting Soil (blomjord): 90% peat, 5% sand, 5% barch mulch
• Potting soil with leca (blomjord med leca): 87% peat, 8% leca 2-6mm 5% sand 0-6mm
• Orchid soil (Orkidéjord): 70% pine bark, 30% peat

These are relatively expensive soils. Cheaper brands are very similar but often up to 95% peat.

Note: Leca balls are like rugged stones, same use as perlite. "Sand" normally means fine sand in Sweden, we have a separate word (grus) for gravel/grit/coarse sand.

Most people who know what they are doing probably buy leca or gravel separately and add as much as they see fit. As you can see, if you visit a store which have all 5 types (most don't) the one with leca has only 8% leca. Not everybody sells the small leca balls though, most stores have only the bigger 8-12mm.

Plants bought here come in these mixes so you have to live with it no matter if you like it or not. But 2/3 potting mix and 1/3 gravel has been confirmed now by 3 experienced persons here to be well drained and suitable for palms in general, one of them sells palm trees for a living.

Houseplant soils in the US

Home Depot is a major chain right? They seem to have only one soil for ordinary plants, the all-purpose mix. Sphagnum peat moss I think is the same I call peat above (usually half "light" and half "dark" here). But then I don't understand the difference between "peat" and "sphagnum peat moss" in the contents or the all-purpose mix. It could be 80% peat afaikt, not 87-95% as in Swedish mixes but not very far from it. "Sand" hopefully means coarse sand in the US. If so, it has 20% "grit" (including sand, perlite etc) compared to the 6-8% leca (and 5-7% sand which may well be to a great extent fine sand) so there's a difference, not big but probably significant (in my world 10% grit is not much, 25-30% is plenty, 20% is almost there). The seed starting...

David, there isn't one good answer to your question. Root rot sets in when the tiny pore spaces within a potting mix or in the native soil become saturated with water....displacing the oxygen. If the roots sit in a saturated medium for even a day, root tips begin to die.

Most of the commercial potting mixes on the market are terrible! Composed of dusty, overly processed peat and not enough of anything else to create the porosity so essential for healthy roots.

My packaged medium is mostly pine bark fines....practically impossible to drive the oxygen from it without actually submerging it! Plants growing in such a porous potting medium laugh at daily rainfalls.

The highly porous mixes require frequent, thorough waterings during the hot summer months. Depending upon the plant (species, size, vigor, amount of sun, etc., I expect to water daily in the hottest time of the year.

The problem with a finely textured medium that holds on to water longer is that after a few days, the available moisture becomes harder and harder for roots to access. Terrible stuff.

When I go away for a few days, I cluster my plants around an inexpensive sprinkler attatched to a garden hose, which is then attached to a timer set for whatever frequency and duration I need.