Ah, the $64,000 question!!! Sorry, just a little unsure really. I have a lovely (hopefully!) Osakazuki in a nice big pot.... bought about a month ago. It has started to leaf but seems to be taking a while, could this be to do with my watering? How long do leaves take to open fully from closed buds? The compost seems to be damp, though of course I can only speak for the top part; I water well every day or so. Is there a way of measuring the moisture levels accurately and adjusting accordingly? Many thanks in advance, Regards, Adrian
However, since you mentioned compost and if you have not read, Vertrees, in Japanese Maples 2nd Ed., writes that “[t]the ideal soil for Japanese Maples is a sandy loam with a low to medium amount of organic matter.” As far as moisture, he writes: “Japanese Maples do not have any unusual moisture requirement. The ‘average’ amount of water supplied to the normal range of landscape shrubs is usually adequate. … The principal water requirement, in our opinion, is a uniform supply of moisture. By this we mean: (1) if the plant is in a fairly dry situation, it should not be flooded with water at irregular intervals; (2) if grown where moisture is plentiful, it should not experience a sudden drying occasion. The moisture supply whether little or much should be constant. … The main point to guard against is very wet periods followed by very dry periods or vice versa. This will surely cause mid-Summer leaf drop or leaf scorch. … Containers must not be allowed to waterlog. The grower must determine the requirement of water for his particular type of soil mix and container quickly as overwatering is almost worse than underwatering. Proper water management is far more important that fertilizer or soil types!” Since your tree is leafing out, however slowly, it is healthy and happy. I believe that your weather there is somewhat similar to ours in the Pacific Northwest, so my guess is that daily watering of a maple in a container is too much; not that you have hurt your tree at this point. Most of my collection is in plastic pots (terracotta requires more water), and it seems that it is from November to May that they are not watered at all because we get so much rain. This year they were watered once in April because we have had unusually high temperatures. Then on average they are watered once to twice a week depending on the month and temperatures. If the soil is damp to touch, it seems that it should be good for some days. Since I have plunged containers of roses into water and have seen that when the bubbles stop the soil is saturated, I must comment that my maples do not receive that much water. I am not saying that this is too much water, especially in other zones, but be careful. Perhaps others water their maples that deeply. How about water running out of the bottom of the pot for a period? It seems that that is somewhat of a measure.
Rootball can dry out and shrink away from pot sides, allowing water to rush out the bottom. So, water coming out the bottom does not demonstrate that potting medium is moistened all the way through at all. Plunge to be sure all is moist, then water normally thereafter.
I agree with what Laurie is saying: every day is too much, unless your container soil mix would drain so much that it would dry out after a day in high temperatures (like in a bonsai style inorganic mix, for instance). I water 1 or twice a week, in high summer. Keep it moist, but not wet. I'd also try to develop a soil as the years go by that drains well in your weather because, if I understand correctly, it rains a lot in Wales? The speed of leafing out depends on the weather, as well, as far as I can see - the temperatures, for instance. Good luck with that beautiful tree.
Put the pot in a tray. Water until some water runs out the bottom; wait half an hour. If the water in the tray all soaks back into the soil, water again, and repeat until a little bit of water doesn't soak back up. Then don't water again, until the pot feels almost completely dry. When it reaches this, then it is time to water again, same quantity as you found necessary the first time. Bear in mind that while the leaves are still in bud, it won't need a lot, but as the leaves expand and temperatures rise, it'll need much more frequent watering (maybe even twice daily in hot summer weather)
Why bother with the tray?* Plunge it until bubbles stop, lift it out. Done. If already moist it won't be long, do not leave it sitting around under water longer than it takes to re-wet it. If actually quite damp when immersed there will be little bubbling, it can be pulled right out. *Two advantages to the tray would be if there is fertilizer on top of the pot that would come off and float if top of potting medium immersed, of if plant will become too heavy and hard to lift out of tub after soaking. Otherwise...
I'd have thought that would lead to total saturation and a rather high risk of over-watering; also excess water draining out after soaking will soon leach out all of the nutrients in the soil leading to poor growth later
Any method that wets the whole soil column will produce the same effect. But, I was not talking about routine watering in this manner, just saying this was a way to check if the plant was actually moist throughout.
Wow! Thanks everyone for all your helpful replies. To elaborate a little, when I have watered there have been bubbles coming to the surface of the pot. I took this to mean that the compost could be dry deeper down, though I cautiously decided this was due to my 'potting on' leaving air pockets where I couldn't pack in the compost. After putting my tree in the new pot (concrete with a single drain hole) I began to worry a little about drainage... I did place several broken crocks in the bottom, but having read so much about drainage, I now wish I had put a layer of large stones too. Anyway, I will water once or twice a week after soaking the whole thing and looking for run off as some of you describe. Thanks again to you all. I'll post a picture one of these days.... Adrian. P.S We get our fair share of rain here (!) but today there is lovely cloudless sky; I may even pop to the beach (day off work). Cheers.
If you water very slowly, using a rose-head can, you can control water going INTO the soil and not worry about it running off the sides. Once this is done til it comes out the drain holes, as long as you keep it just barely moist on top, you should be able to keep it going without having to plunge it again.
Good you didn't put in large stones at the bottom since these type of layers (meaning material that is different from the soil mix) at the bottom of a container would only raise the watertable, and not change the drainage situation in the mix, and therefore the risk of the roots getting 'wet feet'.
Yes: when potting in small containers do not add "drainage material" as water traveling down the soil column will tend to back up when this layer of different texture is encountered, not cross over it until the soil above is at field capacity (quite wet)--at which point it rushes out the bottom, creating the false impression of enhanced drainage.
Adrian, I just wanted to mention that your porous concrete tub is going to draw water out of the soil, so it will need more frequent watering than a plastic tub of the same size, but I do not know what the typical difference would be in our climate.
OK Laurie, thanks.. and thanks to all of you. I guess if I can ensure the whole 'column' is well watered it is then a case of keeping it moist with regular top ups. All the best, and thanks again for your help. Adrian
There is also the issue of salt build up, from fertilizer, etc - the recommendation is to water through regularly, meaning having the water come out the bottom. So again: only water when necessary (as the roots need air, and stagnating water asphyxiates - kills off the finer feeder roots) but watering through helps with salt and gaz built up. Each time you water new air gets 'pushed' into your soil, and gazes 'pushed out'. Salts are washed out. Hope all of this isn't confusing with all the different voices coming in.
I have read that when using regular tap water that it is best to let it sit for a day (salts/chorine evaporates) before watering... or use white vinagar (unsure of measurments)....
Chlorine will evaporate, but chloramines will not (and salts won't evaporate - in fact, the concentration of salts will increase with water evaporation).
Adrian, Im new at this. Whenever I repot a plant I use small rocks in the bottom and then on top of that I add a piece of fine mesh screen to prevent the soil from going through when I water. I also just use the method of sticking my finger into the soil ( down to middle knuckle) and that usually works well. Good luck! Lilmech
I have to admit that this is still the method that I rely on, especially for smaller containers. I've used moisture meters, but have found them to be somewhat inaccurate in the coarse, mostly-inorganic mixes that I use for my potted JMs. Probing into the growing medium to see what's going on down there is still the best way to know for sure. How much and how often to water is dependant on a number of variables, some of which are temperature, relative humidity, air movement, soil type, and plant transpiration rates. In practical terms, this translates into my current watering regime of once or twice a week. In another month or two, I'll have the watering can out every day. The goal is to provide a consistenly moist root zone. Too dry and the trees start shutting down and the increased stress levels invite disease and insect attacks. Too wet and root rot sets in (though I've never seen this here). Potting soils high in peat and other organic material (e.g., compost) might tend to get rather soggy, especially in temperate climates with frequently overcast and/or rainy conditions (a better place than here for JMs). I would be much more concerned about overwatering in such a situation. As a side note, I partially-submerge containerized vegetable and flowers for extended periods in order to effect a deep soaking. I've never done this with potted JMs.
how much water should be sufficient for a japanese maple outside in my garden . i have 2 , one is bushy and a deep burgundy about 3 ft high . it is showing a little curling on the leaves , the other is a dissectum same colour , weeping variety , the top died off of this one as i planted it in the middle of a heat wave last yr , i'm surprised it survived at all , the dissectum looks a little healthier atm .
Adrian In our climate once a week is more than adequate I only have a few Japanese maples in pots, and I only ever water at all when we have been having a dry period (which is very seldom) :) If you have ensured that the plant is in moist soil throughout the extent of the pot, then only water if it hasn't been getting help from the heavens, or once a week if you feel it hasn't been getting enough from nature. Osakasuki is a truly beautiful plant, especially in autumn
Thanks again everyone..... Sam, thanks for the link to your site... if I find myself in your part of the world I will be sure to drop in. Regards, Adrian
Isn't the bottom of the container a different texture therefore causing the same effect. So would the 'drainage material' just really raise the water table by the amount of the drainage ? Cheers.
