Why does anyone put gravel on top of their potted plants?
Comments (36)
hoovb zone 9 sunset 23
6 years ago
isde02(zone5b)
6 years agoRelated Discussions
Should I put gravel on the bottom
Comments (38)Wow - you guys have been busy while I put in a long day. Dan A fine-textured horizon underlying a coarse-textured horizon retards saturated flow (my emphasis) because the small pores do not transmit water as quickly as do large pores. I mention this because it's an important point. From the practical perspective, for both containers and raised beds, we're not really interested in how fast the perched water percolates through this layer (as long as it's not hours and hours or days, and this is a horticultural issue, not a scientific one), only that it does. We have now established that a soil strata that will support a PWT under some conditions (as when it's in a container) and that is resting atop a layer of finer soil will drain into the lower, finer strata, which is a 180* reversal from your original premise. We can probably also agree that the same strata of soil that will support a PWT will not drain when it rests atop a very coarse layer. We know the point at which the capillary pull of the lower strata + the gravity flow potential equals the capillary holding power of the top strata is the point at which the top strata will drain. Let's argue the science through practical examples & see where that leads us: Let's assume we have a container soil that will support a 4" PWT in a container (call it CS4) and we have a 12" deep container. We'll also assume that we can do magical things like setting a soil mass complete with a PWT atop another material. 1) The most important part of the discussion to container gardeners will pertain to what happens when there is a very coarse layer of material under the CS4 soil. Nothing. The CS4 soil will retain 4" of perched water @ container capacity regardless of how much water is added to the soil after container capacity, and regardless of the soil column depth (as long as it is deeper than 4". If it is less than 4" deep, the entire soil column will simply remain saturated.) 2) A homogeneous CS4 from the top of container to bottom will also retain 4" of perched water @ the bottom of the container @ container capacity regardless of how much water is added to the soil after container capacity, and regardless of the soil column depth. My contention is also that if the CS4 was layered atop another strata comprised of particles up to 2.2X the particulate size of the CS4, there would be no impediment to drainage, but this is a minor point & not important to the discussion. 3) If 4" of CS4 is layered above 2" of dry sand (lets imagine that the sand will support a 5" PWT in a container), perched water will move out of the CS4 into the sand until it is saturated. At that point, some or all of the water will perch in the CS4, depending on whether or not the water column has enough gravitational flow potential to overcome the capillarity of the sand. 4) If 4" of CS4 is layered atop 6" of dry sand, all the perched water will move into the sand, as long as the total air porosity of the 6" of sand is greater than the volume of perched water in the CS4. The soil column section would 5 reveal 5" of sand with perched water - 1" of sand with no perched water, and no perched water in the CS4, regardless of height. 5) Now lets use a practical example for raised beds. You have already reversed your position and allowed that perched water will move from a strata of coarser particles into one of finer particles. Since the soil being discussed on the SF forum is a sandy loam, we know that the raised bed soil is very similar in structure to container soils. If it is fine enough to want to retain ANY perched water, we have already seen that the water would readily move downward into the sand unless the sand is saturated. To illustrate this, hold a saturated sponge with the large surfaces horizontal until it stops draining. Set the sponge on several layers of paper towels and note how much water moves into the paper towels. Back to the raised bed ... Since we know the organic mix will freely drain into the sand, sandy loam, even clay loam it makes incorporating any organic material into the native soil a superfluous exercise. Now, in the case where the soil might actually BE saturated, we are warned that incorporating organic material into those soils prone to saturation very often creates the bathtub effect, it should be avoided. You cannot use the argument impermeable in either raised beds or containers because the water is free to move laterally into either thin air or through/under RB walls. If not, it is certainly free to move laterally as the surface of surrounding soil dries. I'll say this gently, but you accused me of working from faulty premises and logic, and of course I disagree. You also accused me of obfuscation, and introducing irrelevant examples several times, yet a couple of paragraphs later you introduce "exfiltration (and evapotranspiration)". Your "Why wouldn't one incorporate nutrients as deeply into the soil as possible?" seems to be irrelevant because your initial justification was that it would eliminate a perched water table. You may note that I've not had to do any back-pedaling on any of my statements, and I haven't had to add qualifications like "generally the rule of thumb", "for most purposes", "this modifies my assertion". You also keep making the point No Gravel, but no one ever argued opposite that point. "I'll try to be a gentleman if you'll be fair. If you read my posts again, you'll see there are few on these forums that remain as focused on the core argument as I. I'm not in thge habit of introducing extraneous points to avoid the issue. I also disagree with Generally, the rule of thumb for larger particle size below is the entire column for most purposes must be saturated to drain. Not always, but if you are advising someone and state this you are correct 85% of the time. As I illustrated above, a soil that supports 4" of perched water in a container will ONLY support 4" max. It's 11 here now. I've been up since 5 and had almost 10 hrs on the road, so I'm weary. I hope what I said is easy enough to string together and understand. ;o) Take care. Al...See Moreglued gravel on top of plants?
Comments (18)......... does the protagonist of this video prune his roots well? If that's the way he habitually root prunes all plants regardless of the degree of congestion, I would say no. For that particular plant, I would say it's fine. I'll explain. The reasons for repotting, which includes root pruning, are to 1) relieve root congestion throughout the entire soil/root mass, 2) increase the volume of soil available for colonization by fine roots which do all the plant's heavy lifting, 3) increase the volume of soil capable of holding resources - water, nutrients, and particularly air. As roots grow they occupy soil pore space which can limit oxygenation even in well-aerated media. The plant repotted in the video was what I would consider to be borderline insofar as whether or not it needed repotting. The soil/root mass barely held together and there were no heavy roots to be seen within the soil mass. Root pruning should focus primarily on removal of heavy roots not attached directly to the base of the trunk, and on removal of roots that are potentially girdling, circling roots, roots growing straight up, down, or back toward the center of the root mass, and crossing or j-hooked roots. There were some roots growing straight down in the video, but they hadn't reached the size where they served only as plumbing rather than an organ that was taking up their fair share of nutrients. He also left the roots in the center of the soil mass to grow larger and for the root mass remaining untouched to continue to increase in congestion; so the effort was a bit closer to potting up than a full repot. Had I been doing the work, I would have sawed the bottom 2/3 of the root mass off, then used a root rake to comb the soil from the remaining roots before selectively removing the heavier and problem roots remaining. I think he would have done a greater service if he had worked on a seriously root-bound plant as opposed to one that wasn't in great need of a repot. (see root rake bottom row 3rd from left, next to the saw. The tool next to it, to the right, is a root hook - useful for combing out heavy roots and digging away a badly compacted soil, the tool that looks like a sickle is for removing stubborn plats from their pots. On the bottom far right is a root pruner. Missing is a pair of heavy scissors.) ..... remind me if the crown or the roots should be pruned first in a ficus? First, allow me to say that a repot with root pruning is stressful to a plant; but the fact is, 2 weeks worth of stress during recovery from a root pruning is a drop in the bucket compared to the lost potential associated with prolonged root congestion. Plants regularly (fully) repotted with root pruning will grow to be many times the size of plants left to languish in pots completely congested with roots; and, they will be healthier all the while for the regular rootwork, all else equal. When it comes to rootwork and pruning the you of the tree, I frequently run into well-meaning individuals quick to assert one should never prune the top when transplanting a tree "because the top is where the food to grow more roots comes from". You'll only hear this from folks unfamiliar with rootwork, and they're just repeating something they memorized, with no understanding of how plants work. Plants are very economical organisms. Plant central ALWAYS knows how much foliage it needs to support the root mass with food, and how much root mass it needs to provide water/nutrients to the top of the plant. What one does to the top causes a reaction in the bottom, and the reciprocal of that is just as true. So, if you do a heavy pruning of the top, roots die back and the top regrows until the plant's chemical messengers inform the plant "we're good, we have balance". When you prune the roots hard, as one might in the first pruning session, it can cause the entire plant to collapse from an adequate supply of water. To see how ridiculous it is to suggest "one should never prune the top to balance the root to shoot ratio" Try lifting a tree in leaf in summer and see what happens. I have had opportunity to lift a number of trees from the landscape in summer, and have found the only way to prevent collapse is to prune them very hard or defoliate the plant if it allows. Repotting is something like lifting a plant in summer as you're leaving a large % of the root mass behind (by removing it), so it is entirely appropriate to ensure there is a reasonable balance of roots to shoots to prevent collapse of the plant. That wasn't to say you should be overly concerned about killing your plants if you don't get the balance just right. It doesn't work that way. With potted plants, you can keep them out of wind in shade for a week or two which significantly reduces transpirational water loss. It's only when you do a really hard root pruning that you need to prune back the top. It would be unusual to have to prune back a houseplant unless you have a big 5-10 gallon tree and really want to reduce the roots significantly. I prune my trees every spring anyway, to remove lanky winter growth, so I typically prune the top and roots of all but needled evergreens when I repot. This includes deciduous, tropicals, subtropicals, and broad-leaf evergreens except those that bloom on old wood. They seldom notice that they've even been pruned, pushing new growth within a week or less in most cases. I've found it's best to prune the top first if you need to, and when you see back-budding just starting to occur, do the repot. I think the time frame would be prune top, then prune roots 2 wks later. The foliage removed reduces water demands on roots and the new growth just starting doesn't yet increase those demands. You'll have leaves already started and willing to grow, but the plant will suspend the top growth until roots recover enough to support continued maturation of the young leaves. It works equally to prune top and bottom at the same time if you were planning on pruning the top anyway. You'd have to take my word on that because you won't have the reassurance of the new branches starting to grow that you normally see if you prune the top 2 weeks before the roots. Al...See Moregave up on planting - putting in pots!
Comments (32)I had a similiar issue in Calgary when I started 10 years ago. I had about 4 to 6 inches of soil then the beige bouldery clay you can not dig through to bury the graft 4 to 6 inches below grade. I built all raised beds about 12 to 14 inches with garden stone and green garden ties to hold the soil in. Where ugly looking I planted juniper (there are other varieties that will do) in front of the ties and stone ... it is a low spreading juniper and eventually gets high enough to hide the raised bed bricks and ties - it is now so dense I could remove the stone and ties and the soil would not bre lost. I put in about 20ft3 of woodland mix from ornamental gardens (at the airport) - it is a large garden by city standards. Lasanga bed would work also just remember it has to be high enough to bury the graft or crown on tender own roots after the soil has settled. I use a rule of thumb with grafted tender roses that I need a total depth of at least 18 inches of good soil. By the way, my way was a lot of work but I went large scale. I have never successfully over wintered roses (tender) in my unheated garage but that does not mean it can not be done here....See MoreDoes anyone do this with their BIG potted trees?
Comments (9)Mikey my friend your orange and lemon tree are gorgeous must smell amazing . Mike I do the same as you especially when the plants go back into the GH it doesn't bother the tree's at all . You would have loved the storm here yesterday there was a lightning bolt every 5 seconds and was the thunder loud . Maybe Mikey if you stop wanting them you will get them more frequently I sure don't want them and we are always getting pounded try it might work lol. Take care. Brian...See More
s g
6 years agoHelen Agius (Adelaide,Sth Aus) USDA Z10b
6 years ago
britters_zone4
6 years agoAlain (Pacifica, CA;10a)
6 years agoAlain (Pacifica, CA;10a)
6 years ago
ewwmayo
6 years agolast modified: 6 years agomyermike_1micha
6 years agolast modified: 6 years agorina_Ontario,Canada 5a
6 years agoI started using gravel as topdressing few years ago to deter squirrels from digging - just as Alain said. It helped a lot. It doesn't work as well against chipmunk, but overall, it helps. Chipmunk will rather bite some leaves than digs, and that is more difficult to prevent. I have many plants with bite marks or chewed off pieces of leaves...And I know for sure it is chipmunks, as I see them doing it! They seem to like juicier leaves:
As ewwmayo said, it also keeps lowest leaves of plants from laying directly on 'soil' and away from water and splashing when it rains.. Some ppl said it interferes with drainage, but definitely not my experience. Maybe it is climate I am in, or mix I use, that is very gritty - or both. I use smaller gravel/grit for smaller pots and get bag of bigger grit, too big for gritty mix and sold as turkey grit just for topdressing. I use topdressing for many plants, not only succulents. Pea gravel works well too, and any type of gravel-grit-decorative rocks.
As for watering, I use bamboo skewer if not sure. I find it much better than poking finger in since it is 'skinny' and I can reach deep inside of mix. Eventually, one gets to know plants and checking the media all the time is not necessary - just as ewwmayo pointed out :)
Greenhouses do not check plants if dry or not at all, they just take the hose on watering day and everything gets sprayed. Succulents often sit in lots of water.
myermike_1micha thanked rina_Ontario,Canada 5amyermike_1micha
6 years agoewwmayo
6 years agoMike - Thanks! I know you already do a fantastic job with your plants already. =)
Another thing I do is watch the plants in your collection that readily show how much water they have stored up. My easiest are Fenestraria, Cheiridopsis, Titanopsis, and Marlothistella. I should have watered today but will get to it tomorrow:
Haworthia are a bit harder to judge because just a day or two in my growing conditions can mean productive growing or a slight setback. I try not to be hard on myself for not always watering on the 'optimal' day.
With small clay pots under lights, you should have a pretty high level of forgiveness if you do somehow mess it up. In dire circumstances, one can wick up excess moisture by placing clay pots on stacked paper towels and letting a fan blow over them continuously.
I've had to do it on those days where I was too exhausted/not paying attention and fully watered something that should have stayed totally dry. That was so stressful!
myermike_1micha thanked ewwmayomyermike_1micha
6 years agolast modified: 6 years agoEwwmayo fantastic. Such a gift you have there and such beautiful plants. I think I'll get the hang of it. I'm turning to pebbles because they hold them in place in the pots and don't look bad either. Too I spray my plants soil so I don't want wet soil bouncing back up into the trunks of many of plants. I got the idea of using stones fro all of you here. I was always afraid to use them but seeing how popular this method is and how successful everyone is tells me I can do the same ! Thanks kid
Karen. Good to see you around. It's been a while since we talked and how are the plants doing I sent you ? Hopefully your well ) and thanks for your suggestions as always.
Rina thank you !! For your survival gift. Here you go They should be fine. Between you and Felix which I will post too I have all kinds of varieties. By the way, THANK YOU for sending me labels with them. Wow
They will do well. Notice the pebbles ?
myermike_1micha
6 years ago
SpanishFly - (Mediterranean)
6 years agolast modified: 6 years agoI put a top dressing of (usually) marble chippings on my soil mix. As well as being attractive, it gives some shade to seedlings that sprout on their own, after seed has fallen off Momma. One of my Lophophora williamsii with a number of self seeded sprouts.
myermike_1micha thanked SpanishFly - (Mediterranean)Maria (6b)
6 years agoI started adding top dressing because I liked the look. But then I realized that besides the looking nice it is useful. I really don't like the look of yellowed perlite floating to the top of the soil with each watering... well, top dressing hides that. It also weights the soil down and helps keep the plants upright for the first few weeks after repotting or if the plant has undeveloped roots. It keeps the wet soil away from the plant's base (I'm talking especially about cacti - with the top dressing they don't sit directly on the soil, and after watering the top dressing dries much quicker than soil underneath it).
As far as watering goes I'm using wooden skwer method, in case of those with fat leaves - the squishines factor.
And this is my bottle-neck with minimal roots and wide base. My mother used to bury quite a bit of it to keep it upright (see the lower yellowish part? that much).
But I don't always use top dressing. I don't really like it for Jades (the Gollum is an exception).
myermike_1micha thanked Maria (6b)
nanzjade z5 MA
6 years agoohh my goodness.
Last night I took this photo to show one of the rare times that I use top dressing... to finish the look of a handmade ceramic pot.
I hadn't watered it or it's similar sized neighbors in at least two weeks, and heats been running a lot, so I went ahead and watered it.
This afternoon I hear a swoosh of pebbles crashing and see my brown torti kitty running quickly... this is what I found. (It fell a foot)
Now you can see how it looked without top dressing, lol!
So, as I am looking at the damage, I see my old calico kitty looking out the window like there is something out there. I'm expecting, a bird, or a neighborhood kitty. I see a huge bear by the end of the driveway!
nanzjade z5 MA
6 years agomyermike_1micha
6 years agomyermike_1micha
6 years agolast modified: 6 years agoFelix just as promised. These pics were taken right after I potted them up. Wanted to give them a day or two to acclimate before I watered and a couple I already did. Boy today they looked nice! I will take an update once they are all watered and perked up..Thanks again
Paul MI
6 years agomyermike_1micha
6 years agorina_Ontario,Canada 5a
6 years agolast modified: 6 years agomyermike_1micha thanked rina_Ontario,Canada 5amyermike_1micha
6 years agoRockdale (RI Z6)
6 years ago
ewwmayo