natal mahognany- leaves curling under

I have a 10ft natal mahogany that I bought last summer (indoor). I had to wait for it to be treated for scale and have been monitoring it carefully for any recurrance. So far none of that. The problem is the edges of the leaves curling under and eventually turns brown and the brown part falls away. Because of the jagged appearance of the leaves I initially thought it was an insect pest, but careful examination ( with a magnifying glass) and I can't find anything. The affected leaves then slowly dies. Any suggestions ?

What kind of soil is it in? how long since last repot? what are you fertilizing with? how often?

When you water, are you flushing the soil so that at least 10-15% of the total volume of water you applied exits the drain hole?

Al

It's in a mix of good quality potting soil with perlite and a bit of sand mixed in. I repotted it last summer when it first arrived. The ceramic pot is 15in tall with a 16in diametre. It was 1-2 in bigger all the way around with 3-4 in at the bottom under the tree when I repotted it. I lightly fertilize it with Plant-prod house plant fertilizer 15-15-18 q3-4 wks over the winter. It's sitting in a wide ceramic tray. Water runs out when I water it although probably not 10-15%. I use a 2ish litre watering can. I try to water it every 2 days as I read these plants need a lot of water.

lee

It's being over-watered and probably has a very high level of soluble salts in the slow soil, which is why it's probably dying of thirst in a sea of plenty and why you're seeing a drought response. I would immediately flush the soil and allow the plant to dry down until the soil is almost completely dry before watering again. I would also repot in early summer. Repotting is not the same as potting up - it includes bare-rooting the plant and pruning back the largest roots. If you're interested in learning what steps to take to save your tree and learning how to tend to it in a container so you can restore vitality and maintain it indefinitely, let me know.

Al

Wow, that is a great answer. Yes, my tree is important to me. We moved into our house with an open 2 storey foyer. It has 5 stems and I'm looking forward to watching it grow to fill the space. Please continue with your instuctions.
lee

For now: Completely saturate the soil with room temp water & leave the plant rest for about 15 minutes; then, repeatedly flush the soil by pouring at least a volume of water equal to that of the container it's in through the soil several times - at least 5-6. After the planting has stopped draining, remove it from its container and check for root rot. If you find none, set it (still unpotted) on folded newspaper. If the container holds more than 2-3 gallons, leave it on the paper overnight and return it to the container in the AM. Add a wick to the drain hole. If the root/soil volume is less than that, leave it on the newspaper for 4 or 5 hours before you return the plant to its pot - with the wick. The wick will help remove excess water if you use it properly. I'll expand on that thought if you intend to follow the instructions and you remind me.

You'll want to get the plant outdoors as soon as night temps are reliably above 55*, and repot a month or so after that. I'll help you through the repot when it's time.

After you flush the soil, you'll need to fertilize when the plant next needs watering. You can either trust me that a 3:1:2 RATIO (like 24-8-16, 12-4-8, or 9-3-6) is your best choice, or I can point you to a thread that makes the case in detail. Fertilize at half recommended strength.

If you discover there are sour smelling or slimy/rotted roots, when you unpot the planting, let me know & I'll help you through an emergency repot.

Al

Thanks
Not to be argumentative, but why would I put it outside. Won't it be shocked when it comes back in from the reduced light level. I looked up the avr daily min temp for where I live and even in June/July it's only 13.5 C (55 F = 13C). Sad but true.

any advice on the soil mix

Lee

You have a point about the temps, but notice I made a caveat about night temps being reliably above 55* because I noted where you live. I'll leave that decision up to you, but I have 100+ tropical and subtropical woody plants in containers that I over-winter indoors, but move outdoors as soon as temps allow (+ the 150 or so temperate plants I tend as bonsai that don't come indoors). They do ok under lights, but thrive outdoors in the improved light and elements. These plants build up a much larger store of energy reserves which helps them get through the winter with no bug/disease issues.

I use a gritty and extremely durable soil made of equal parts by volume of Turface (calcined clay particles), crushed granite, and uncomposted pine or fir bark. The Turface and granite are around the 1/8" size and the bark is a little larger. Trees and houseplants love it.

See Post #7520710 toward the bottom of this thread for a picture:

http://davesgarden.com/community/forums/t/719569/

The information in the original post of that thread is a very important concept to understand as it relates to container gardening.

Al

Where would I find the the crushed granite and Turface
Lee

That's a problem, because I have no idea what these products might be called in Canada. Turface is calcined (baked at high temperatures) clay, and crushed granite is often sold as chicken grit, but it's important that you don't use a grit made with shellfish as a part of its make up.

In this picture, the tan material is screened Turface and the white material is crushed granite - chicken grit in grower size.

Al

This message was edited Apr 10, 2010 10:03 AM

This is what the soil I use looks like:

Al

Today did the flushing with many 5 gallon buckets of water (one large flood onto the floor at the beginning until I got the siphon running properly. Afterwards pulled the tree out of the pot- the root system has grown out to the edge, but no sign of any rot. It's sitting on newspaper for the night.
Still trying to research where to buy the turface and crushed granite. As this may take a few days it's likely that I will put it back in the pot tomorrow. How do I put a wick in. The pot has 3 1 inch holes in the bottom.
Lee

Fold a piece of cord over the tip of a straight slot screwdriver and hold both ends tight. Push the cord well up into the soil where it will stay when you withdraw the screwdriver. I use strips of 100% rayon (man made chamois) or strands from a rayon mop head). Cotton doesn't last long, so try to avoid it.

Al

I assume I'm doing this up into the root ball from the bottom.

Mmhmm. Correct.

Al

I have the turface MVP 50lb ($19 from local gardening store) and the grit 25kg ($10) from the local feed store. Located the pine bark, but need to buy it tomorrow.
My tree is still out of its pot because the root ball is still quite yet. Can you describe how to repot it with the new mixture as the root ball currently would fill the pot.

Lee

Your repot should include bare-rooting and root pruning. Please read this thread and come back with any questions you have:

http://forums.gardenweb.com/forums/load/maple/msg1223090628537.html

Al

I've read the thread above. You mention
"The list of genera is long & I treat almost everything except conifers this way (some pines, junipers, etc., don't tolerate being bare-rooted as well as deciduous & tropical trees with leaves). After the initial pruning, my root-balls are a mass of roots all thinner than cooked spaghetti. When I'm done pruning, most root-balls end up being disc-shaped and about 2-3 inches thick (deep). I grow Malus (apple), Ulmus (elm), Betula (birch), Tilia (linden), Pyracantha, Prunus (plum), Morus (Mulberry), Euonymous (burning bush), Fagus (beech), Buxus (boxwood), Berberis (barberry), Carpinus (hornbeam), Salix (willow), and many more. I also treat All the tropicals I grow in similar fashion".

What do you mean by 'tropical trees with leaves' ? I also have a Ficus that is healthy looking but has stopped growing in spite of potting up twice in the last 3 years.

Lee

Leaves, as opposed to needles.

All trees slow or stop branch extension when they are badly root bound, which is very likely the problem with your fig tree. Usually interior foliage is shed as well, and your tree gets that 'tufted' or 'pom pon' look. Experienced bonsai practitioners can tell at a cursory glance if your tree is root bound, simply by observing the increasing or decreasing distance between leaf bundle scars. Potting up isn't enough to fix the problem. Growth begins to be affected at about the point where the root/soil mass remains intact when you lift it from the pot. Any time you allow the roots to get tighter than that, it has a permanent and negative influence on growth - even if the plant was hardy in your zone and you had planted it out (in the ground) - unless you properly tend to the roots and correct the issues.

The reason that bonsai trees can live for hundreds of years and be passed down from generation to generation, while most of us can't keep a tree in a pot growing with good vitality for more than a couple of years is root work. Bonsai practitioners know how to properly prune roots, which guarantees a minimum volume of thick, useless roots that clog the soil and make it difficult to impossible for fine roots to grow, and a maximum volume of very fine roots - roots that do 99% of the work.

Al

But aren't the natal mahogany and the ficus tropical trees with leaves. How do you know which will tolerate this procedure

Lee

I don't understand what you're asking. I said that tropical trees with leaves (as opposed to some conifers [with needles] ) tolerate root work well.

Al

I re-potted today. I used your 3 part mix and then a few handfuls of the old soil. When I came back to make my reply I realized I didn't remove all of the soil with a hose- in the house I could have dipped it in a bucket of water. I gave it a really good shake before putting it back in the pot. If it's super important I can take it out and rinse it out. I have watered it slowly until water came out the bottom. when should I start fertilizing it.
Lee

As long as almost all the soil was removed, it's no problem, you can finish the job later when you next repot.

Fertilize after 2-3 weeks when you start seeing evidence of new growth, It has nothing to do with new roots being too tender - roots initially colonize containers faster when the soil is low in fertility.

Secure the tree to the pot so it can't move (relative to the pot) when it's jostled or you decide to shift the container. This makes reestablishment much faster.

FWIW - I mentioned in a couple of places upthread that it would be better to wait until summer to repot. Tropicals and subtropicals respond best to major procedures if you undertake them in the month prior to the most robust part of the growth cycle. For you, that would be very late Jun or early Jul.

Al

Yikes, my miniature Daschund has taken a liking to the pine bark nuggets and every time I go out she raids the pot and chews them up all over the place. keeps things interesting.

lee

It's only been 2 weeks since the repot so I'm resisting the urge to fertilize it, but the tree seriously looks like it's dying. It's tied up so no diturbance. Can't put it outside -too cold. Time will tell. Anything else for me to do.

Lee

I saw the picture you mailed. I would just be sure the soil is only moist and not wet. Keep it in good light. Don't fertilize yet. You want the level of solubles in the soil to be as low as possible for now - to make it as easy as possible for the plant to absorb water. Hopefully, you were careful to be sure the soil is distributed throughout the entire root mass.

My assessment: Late June or July would have been much better timing for repotting a tropical tree. It LOOKS like your tree will shed this flush of foliage, but judging by the number of leaves and how they are distributed on the tree, the tree was retaining reasonable vitality, so it SHOULD have enough energy reserves to push a new flush of foliage behind what it will probably shed.

That's not the end of the world, just a little setback (unless it doesn't happen). Watch leaf axils (the crotch where leaves meet stem) carefully for signs of new growth. If you see it, you're prolly home free. Your main concern now is to get the watering right. You want the soil damp - not soaking wet. Fertilize with a half strength dose of a 3:1:2 ratio fertilizer like 24-8-16, 12-4-8, 9-3-6, only after evidence of new growth.

Al

To me it seems the 2/3 inorganic mix doesn't retain enough moisture so I worry the root ball isn't getting much water. It's encouraging that it may still sprout new foliage. My 10 year is telling everyone I killed my $250 tree because I listened to a stranger on the internet.
Thanks
Lee

Let's be fair. If you go back up and look at the thread, you'll see I gave instructions on how to flush the excess salts from the soil now, and said very plainly it's better to repot in early summer rather than to repot now, when your plant is at it's lowest energy level of the growth cycle. It's not the soil. I have 250-300 trees growing in that soil and I've repotted over 100 temperate trees into it so far this spring ...... and I'll repot another 100 tropical trees into it between Memorial day the 4th of July. Hundreds (literally) of others are using it as well, and all reporting excellent success.

Al

It was more of a comment/question rather than blame/criticism. I checked, and just like you said there are little 'buds' emerging just above the old branches connect to their trunk. Very interesting process.

Thanks
Lee

Good - I'm relieved for you. I'm actually surprised at the extent of the wilting evident in the photo you sent. I'm not sure why it occurred, but it's very unusual for any of my trees to shed foliage when I repot, even though in trees with lower levels of cuticular wax some wilting is common. I beg a pardon for misinterpreting your comment. I'll keep my fingers crossed that the patient recovers quickly and fully.

BTW - I often do woody material repotting demonstrations for various clubs. It's much easier to SHOW someone how to repot in a hands-on setting than it is to describe it over the net. ;o)

Good luck!

Al

Will keep you updated. definitely let me know when you're doing any demos. This time of year it gets a little crazy not just because of gardening -show season starts with the horses.
Thanks
Lee