Drainage Test

[Mike M]

I conducted a drainage test on the slope today. The hole was deeper than a 15 gallon container and i filled it with approx 5 gallons of water and it drained in just over an hour and a half. The issue I see is that the bottom stays muddy as the sandstone seems to hold the moisture at the hardpan. I have lost palms to root rot an I suspect that the drainage is good but the bottom of the hole never dries thus rotting the roots.

Thoughts please

[MattyB]

I suspect you're interpreting this wrong. 1.5 hrs to drain that hole is excellent drainage. The mud in the bottom is probably the fine sediment/clay layer all concentrated at the bottom. I know you said you lost things to root rot, and I could very well be wrong, but my instincts tell me that you're in a good situation and I personally wouldn't bust out the downslope side of that hole to increase drainage because you'll make it too dry.

Maybe someone like Brett Quaman, or Matt in SD,who has a sandstone slope can help more.

[Mike M]

Good info. Thanks matty. The drainage is good for sure. I am thinking the roots won't penetrate the the native thus creating a bowl of sorts. Seems like the palms grow until they hit the native and then everything stops. This is where I think the amendment with compost will help me.

[MattyB]

Yeah, I can envision that. Like a pot in the ground. Eventually the palm will get rootbound. So, you've gotta put in work digging a very large hole, that will help. But I think you have a few inches of topsoil, and that coupled with a thick mulch layer should allow the roots to pancake out as the palm gets large. I've planted in pure rock holes and it does work.

I was thinking you could maybe drill a few deep holes in the bottom of your planting hole, using a long masonry bit.

[Mauna Kea Cloudforest]

I grow palms in the sand stone on my hillside, water drains quite a bit faster, though. In a freshly dug hole, it takes about 15 minutes to drain a 5 gallon hole and about an hour for a 15 gallon hole. And at the end there is mud in the hole that stays there as well. I've never, ever seen root rot. I suspect you're not getting root rot, but drying out instead. That's been my biggest problem, but using drip or micro-bubblers has solved the problem for me.

When digging holes, I usually have to use a steel crow bar to remove giant chunks of sandstone. I do try to make the hole deeper, but I only backfill with native soil, the goal is just to remove the sand stone. Palms go crazy in this soil provided I add plenty of water and fertilizer. I have failed to be able to successfully grow bananas and avocados up there, but palms just seem to love the sand stone.

The beauty of the sand stone is that in a warm Winter like this, the soil is actually warm. The bummer is that I am watering as if it was Summer because the hillside won't retain any moisture.

The biggest nightmare are the pesky moles that constantly tunnel in the hillside. I have to remove the holes so that the irrigation works properly, otherwise the water just drains away. I've tried everything to remove the moles, zero success so far.

[Sabal Steve]

I grow palms in the sand stone on my hillside, water drains quite a bit faster, though. In a freshly dug hole, it takes about 15 minutes to drain a 5 gallon hole and about an hour for a 15 gallon hole. And at the end there is mud in the hole that stays there as well. I've never, ever seen root rot. I suspect you're not getting root rot, but drying out instead. That's been my biggest problem, but using drip or micro-bubblers has solved the problem for me. When digging holes, I usually have to use a steel crow bar to remove giant chunks of sandstone. I do try to make the hole deeper, but I only backfill with native soil, the goal is just to remove the sand stone. Palms go crazy in this soil provided I add plenty of water and fertilizer. I have failed to be able to successfully grow bananas and avocados up there, but palms just seem to love the sand stone. The beauty of the sand stone is that in a warm Winter like this, the soil is actually warm. The bummer is that I am watering as if it was Summer because the hillside won't retain any moisture. The biggest nightmare are the pesky moles that constantly tunnel in the hillside. I have to remove the holes so that the irrigation works properly, otherwise the water just drains away. I've tried everything to remove the moles, zero success so far.

Feral cats?

[Mauna Kea Cloudforest]

We have two feral cats, they've caught one mole so far in two years.

Just as a testament to how well palms grow in sandstone, here's a couple of photos. It just took me years to master how to do it, I killed many things in the process. It's all about the proper irrigation techniques.

[Mike M]

Insight on the irrigatin please.

[Mauna Kea Cloudforest]

Insight on the irrigatin please.

I'll give you my entire recipe for planting and irrigation, it has worked wonders for me.

1) I make a hole that is generally just slightly bigger than the actual potted palm. I remove all the sand stone a little deeper than the pot (unless it's a brahea, which seem to love rock), but I put the native soil back in and I compact it slightly so that the plant doesn't sink after planting. I never put in compost down there because it can go anaerobic during the first 3 months after planting. Any organics under the root ball can cause rot.

2) I usually make sure that the soil line is slightly below the lower edge of the hole so that I can make a bit of a swale, but not too deep so that if needed, I can break down the swale during the wettest part of the rainy season.

3) When I put the rootball into the hole, I make sure the heel is on the upper side of the hill so that the palm tillers downslope over time. This is very important, otherwise the palm will tiller into the hillside and bury itself. For non-tillering palms, I make sure the soil line doesn't go above the base of the palm.

4) Once the root ball is in place in the hole, I backfill native soil only to 1/2 of the depth of the hole. I then take commercial organic soil amendment to fill the remaining depth of the hole. The idea is that water can more easily drain and pool in the upper half of the hole and slowly infiltrate the root ball while watering supplementally. I pop in one Lutz potassium deficiency spike to feed. Note that you should never fill the top with native soil, it can "lock in" the root ball, i.e. the water penetrates the native soil and follows the native soil only via capillary action but the capillary action doesn't jump the barrier between native soil and root ball so the root ball dries out.

5) I make sure to place a micro-bubbler right on top of the actual root ball, not on the side of it with the goal to have the root ball remain moist. The biggest risk with planting in this type of sandy soil is that the root ball can dry out even if the surrounding soil is wet. Re-wetting is then almost impossible. I also do supplemental manual watering 2-3 x week for the first 3 months to get the palm well established. For marginal palms, I extend supplemental for a year but I do it only once a week.

This has worked well so far. It t

[Mike M]

Axel. Thanks so much. Very useful info. Mike

[wanti]

Hi Axel,

Do the recipie appy on sand and flat terrain (maybe except for point 3) ?

I live on a huge island formed by the Danube river and basically the soil here is the sand accumulated by the river over time. I'll plant my first outside palm soon (a simple fortunei) but I want to make it right

What I know by experience with other plants is that water goes through the native soil like knife in the butter.

Thanks a lot,

Janos