When-to-water Question using Moisture meter

chkaplan

Hi again,

I recently purchased a moisture meter to ensure I wouldn't overwater my Ficus and Juniper (especially the Juniper!).

The problem I have however is that up to 1 inch deep the level shows moist-dry, whereas in the bottom of the pot it still says very wet. I haven't watered either plant (except some misting on the foliage) in the past week, and the bottom of the pot is still too wet. I have read on several posts, and in books that you should water once the top soil is dry, but in my case the top soil will be dry, and the deeper soil overwatered. Do I need to repot with new soil, or simply wait for the bottom to dry out a bit more, since the roots on the bottom will rot otherwise?

Thanks!
C.

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Aaron_K

Hi chkaplan,

The soil in the bottom of the pot being wet isn't going to cause a problem unless it is very soggy, compact and contains a lot of small particles. When soil becomes like this, it provides an ideal breeding ground for fungus and bacteria which leads to root rot and ultimately the death of the tree.

Is it you that is on the 25th floor of a tower block? If these trees are being kept indoors (which the juniper shouldn't be) and you have held off watering for a week and the soil is still very wet, then you might consider changing it upon the next repot, for a mix that contains less organics and drains better. Without knowing what your soil is like, I am just making reasoned assumptions.

If you could post a picture it would be much more helpful.

All the best,

Aaron

__________________
Do not follow where the path may lead. Go instead where there is no path and leave a trail. - Muriel Strode

Vulpes pilum mutat, non mores!

"A fox may change its skin but never its character"

chkaplan

Yes I am Mr. 25th floor Bonsai-man!

As for the soil mix, I am not sure what the composition is because I haven't repotted since purchase. My Juniper (and yes I know now that they need to be outdoors, but what am I to do for the time being, hang it on a thread out the window..?:-) was bought in October, before I really begun getting serious about bonsai, and did not know really anything about them. My Ficus was purchased 2 weeks ago.

I think the soil mix might be cheapo-mix, but at least there is nothing glued on the top of the soil! My intuition tells me to change the soil in spring so I know the composition, and can water accordingly. I will also contact the nursery for details.

sauce

Hi 25th floor bonsai guy I would definitely consider a soil change. A lot of trees sold as bonsai come from nurseries that aren't truly bonsai nurseries, if you know what I mean. They might be planted in top soil or potting soil which isn't conducive to good growth. Your soil should drain freely through the bottom of the pot and at the same time retain moisture without suffocating the roots. This will allow much needed oxygen to reach the roots. I've never used a moisture meter I use toothpicks if I'm in doubt.

stephenr

Hi, aKachkaplan (aka - 25th Floor Bonsai-man),
I too have started using a moisture meter to check my pots, but a word of caution - they are not always accurate and you should check using other methods as well to be on the safe side. I also would recommend changing the growing medium to a more free draining mix and check the container drain holes to ensure they will provide adequate drainage. A really good free draining mix means that you will need to check & water more often (especially in hot weather) but it’s worth the trouble to ensure the health of the tree.

__________________
"We grow by attempting that which is difficult, not what is easy"

Aaron_K

Hi chkaplan,


If your ficus is one of the mass produced trees, which I think Sauce was referring to, that are imported from the far east (usually in a speckled blue pot) I would recommend changing the soil at the earliest possible convenience. The reason being is that before these trees are shipped, they have thick clay placed right at the base of the trunk of the tree and then some kind of composted soil. This keeps the roots moist during the long journey.

Unfortunately, the nurseries and vendors that take receipt of these bonsai, don't repot the trees, and by the time you buy one, the tree could have been sat in that soil for a year or two. It is left to the likes of you and I to wash this crappy soil off, for a better mixture to be used in its place. More often than not, one discovers rot already working its way through the root mass.

As your tree is going to be kept indoors, you can essentially repot it at any time throughout the year. Have a read up on some soil mixes that people use for ficus. Come to think of it, as you don't have a yard or somewhere to screen soil without trashing your apartment, it might be best to purchase a premixed soil. Orchid or Cactus soils are usually a good route, as they drain very well.

All the best,

Aaron

__________________
Do not follow where the path may lead. Go instead where there is no path and leave a trail. - Muriel Strode

Vulpes pilum mutat, non mores!

"A fox may change its skin but never its character"

chkaplan

Thanks for the info. I will get my hands on some soil mix pronto and repot my little trees. When I buy a good free-draining mix do I still need to put clay particles in the bottom of the pot, or would it be sufficient to just repot with the soil if it contain sand/clay or some other drainage-improver?
Rgds
C.

Aaron_K

Hi C,

You should be fine with just using one of the premade mixes that is free from fine particles. Its these particles that take up airspace and turn into a swamp when water is added.

All the best,

Aaron

__________________
Do not follow where the path may lead. Go instead where there is no path and leave a trail. - Muriel Strode

Vulpes pilum mutat, non mores!

"A fox may change its skin but never its character"

gregb

C--there is a way you can check if your pot is retaining too much moisture between waterings. Assuming your trees are relatively small in size, take one over to the sink and carefully tilt the pot on its side (not so far all the soil falls out) if it is over-saturated, you may see water come all the way to the rim of the pot. If the pot is colonized by roots, it should be O.K. to drain off some of this excess water without having all the soil fall out as well. This could be a way to drain off excess water until you have a chance to re-pot at a better time (closer to spring)

Another thing you can try is to hold your hand over the soil surface while you try tilting the pot to avoid soil from falling out. This isn't a problem for me because I keep my trees outside and am able to grow moss on the soil surface and I tie my trees in well at time of re-pot. I can take most any pot and tilt it over on its side without any soil loss or the tree falling out of the pot. It is normal to have some sort of "perched layer" of water in a bonsai pot anyway; this is what I think your water meter is picking up on. Even with the free-est draining mixes there is always a small amount of water that remains at the bottom of the pot--this is referred to as the "perched layer" and when you keep a tree indoors as you are doing, this layer never goes completely away. It's helpful to have it during the active growing season and acts as a sort of water bank so we don't have to stand there and water the tree all day. That's why you may have to artificially drain this layer off between waterings if you continue to keep the trees indoors. I find myself doing this at times during transitional weather (spring and fall) with certain trees that seem to retain more water than the rest. Just an alternative for you to consider for your current growing conditions.