Roots growing down or out?

[DALION]

I had a friend ask me if I knew what palms have root that grow straight down because he wants to plant a couple palms. I said the roots follow the water so water slowly for a long time and most of the roots will go down but the roots will also grow out. He then said his neighbor said he is a lifelong gardener and queen palm roots grow out and kings go down. Is this guy off his rocker or am I wrong?

[QUINNPALMS]

From my experience it seems to depend solely on soil conditions.

[Turtile]

Most roots occur in the first 10 inches. The depth depends on the aeration of the soil. Palms are monocots so they don't have tap roots like hard wood trees (dicots). The root system is like grass.

[MattyB]

I've found that the roots usually go down first. That is, when a palm is small, most of its roots will go down. After time, the root mass becomes solid directly underneath the trunk, and the newer roots, that form adventitiously on the outside of the trunk as it expands, cannot go straight down, because there's already roots there, so they start to go out more and more. Then when the tree is really old the new roots end up going almost horizontally, I'm assuming because it's the path of least resistance.

I'm sure someone like Ken Johnson, who gets down there and works with the roots, can confirm or deny this.

[sonoranfans]

sabals, brahea armata, bismarckias grow down a lot if the soil isn't constantly flooded. Also beccariophoenix alfredii grows a deep root system. Borassus aethiopum, hyphaene sp, and phoenix reclinata all have a rep for growing deep roots in Africa... But I also agree soil conditions are dominant. In sandy soil Ive seen phx roebelinis with roots more than 3' deep(I dug it out, dang what a pain).

[MattyB]

Here's my palm sketch for the day...

[DALION]

So roots will still grow out horizontally regardless. I felt puzzled by the question because I have seen roots spread out and rather deep on palms I have dug up but never thought why since I felt it was just looking for water. Thanks for the info.

[DoomsDave]

Dalion, your question might be more interesting than meets the eye.

Some palms grow down, and I mean straight down, like Dypsis plumosa. Big potted plants won't form much of a rootball, but will instead make a mat of roots on the very bottom of the pot, then shooting out the drain holes.

So, Dalion, what is your neighbor's real question? Is he concerned about breaking sidewalks (not a problem) or planting a lot of palms close together but still wanting to plant other plants under them, which can be a problem.

I had a bunch of queen palms planted close together and they sucked so much water out of the soil not much would grow near them, even weeds, or plants like Vinca Major that don't give up easily. Kings are thirstier, but, they don't suck as much water out of the soil.

[DALION]

Dave its not my neighbor. The guy is supposedly a gardener so he should know that palms dont damage hardscapes. I just posted the question because I thought all palm roots moved with the water which means down and out.

[Mike M]

If you are on drip irrigation only, would the roots grow down rather than out as the water flows? I am aware of capillary action but I have found that roots moving outward cant find the water sources. One down fall to drip only irrigation?

Edited January 29, 2014 by Mike M

[DoomsDave]

Well, there is no simple answer to the question.

Some grow down, others grow out, others do both.