Does adding perlite to planting hole count as good drainage?

I know building a raised bed or planting on (in?) a slope provide good drainage. But, what if you dig a hole and add extra perlite to lighten heavy clay soil and allow water to drain through quickly?

Beds that existed before we purchased our home are not raised, or they may have started as raised but over time the are level with the lawn. I have a a new lily coming that requires excellent draining and I want to plant it in one of the older beds. Do you think adding perlite to the planting hole might improve drainage?

thanks for your help.

If you're just amending a small area what you're doing is in effect creating a clay bowl for your plant--water can drain through the soil/perlite mixture, but when it gets to the bottom of the hole and runs into the clay it isn't able to drain quickly past that, so you can end up with an effect similar to growing a plant in a container with no holes in the bottom. If you can amend over a large area and go deep enough that the lily's roots will always be well away from the bottom of the "container" that you're creating then you may be OK, but if the roots grow down and end up in the bottom layer of soil just above the clay where things are going to stay wet for a long time then you won't be any better off than if you'd just planted it in the clay in the first place.

rats! what you say makes perfect sense. A long time ago somebody suggested to me adding small pebbles to a hole for improving drainage. It created what you describe as a bowl and the tree died fast.

Amending the entire bed is not an option. The rest of the plants do well/thrive there and I don't want to disturb a large area. I topdress with compost and mulch each year but I doubt that has totally changed my soil, improved yes, but not changed.

I wonder, ecrane, if I could amend the planting hole AND create a mound just for my lily. That should give that lily about 1 ft of root space. Wonder if that would be enough. The logical thing would be for me to get a more tolerant cultivar or make another bed but, I want this particular one so bad! lol

The amended hole plus mound would work in the short term...long term I have no idea how large a lily's root system will get but a foot doesn't seem very large, and you have to factor in that water will accumulate in the bottom few inches of the good soil as well while it's waiting to drain out through the clay, so I expect it's a fairly short term solution. For an annual that's only going to be around for a year and has fairly shallow roots something like that would be fine, but for a lily that should be growing and coming back every year I expect you'll run into trouble within a year or two.

Or you could try growing the lily in a container instead, that way you've got more control over the drainage (tapla has some great insights on drainage in containers in the container gardening forum if you haven't read his threads before)

I've amended down two feet with good results. Plants have thrived for several years.

I know when I lived in Virginia that the clay was a layer you could actually dig below. I did that with good results, putting a "chimney" of gravel between the plant roots and down past the clay.

From what I understand, worked clayey soil develops hard pan which sounds like what ecrane is describing .. there is a product called septic seep which is also used agriculturally to break up hard pan. I used it when my drain field failed for my septic tank and was utterly amazed to see it fixed it to like new conditions. Saved me bunches of money.

http://www.septicseep.com/

Might be something to look into.

X

It doesn't have to be hardpan to have the effect I was describing, I was talking about regular clay soil. How serious the problem is depends on really how much clay you have, if the soil is only a little bit on the clay side then it may still drain OK and you won't have problems, but if it's heavier clay you'll run into that problem--water will drain really fast through the perlite amended layer, but then gets stuck at the bottom since it won't drain out through the clay nearly as quickly.

Started looking that up and found that it is calcium polysufide. Also known as lime sulfer and hydrogen sulfide. Pretty dangerous stuff.

Would greensand work as well?

thanks everybody for your comments. I mixed compost with bank sand, dug a ft hole and backfilled with amendment. Then planted a salvia (Argentine Skies), which also requires fast draining soil and sort of built a berm with the compost/sand mix. This will be my experiment and I'll watch to see if this truly drains faster than the rest of the bed.

I have clay soil but I'm religious about applying amendments yearly and after several years it is paying off big time. The beds where I did this right from the get go are fluffy and easy to manuever. As the the old beds, I'll let the established plants be and just amend the soil in the planted hole. I'll cross my fingers on the lily that will be planted in the spring.

my friend swears by green sand but I have never used it myself. I do notice that in the many ocassions where we have purchased the same plant, hers are always bigger. Don't know if that's the key but the diff. is significant.

I am going to try adding gypsum to my worst spots of hard clay this year.
http://www.humeseeds.com/gypsum.htm

Thanks CA_Sue, I'm going to try that too.

Hi everyone, I am fairly new here at DG, been looking around for a few months now. I too have clay soil, yuck! When I started my flower garden around my patio here is what I did, I purchased a bale of peat (it ended up being 2), top soil, blood meal bone meal and did spinkle a little gypsum, from what I understand it doesn't take a whole of it, I have a small tiller, I mixed and tilled and mixed and tilled. I also mulched heavy for first year. I still have to mulch, just not as much now. Then when I planted each plant, when I dig the hole I used some of the top soil and peat into the hole. I have lost a few plants but not many. This may not work for everyone, and the bone and blood will draw your critters to roll and dig in the dirt if you don't keep them away.

Vossner I too suffer from clayey soil and have been improving the existing beds with manure and compost. I also dig in some of my leaves in the spring and the worms are doing alot of the work for me breaking up the clay while working the leaves. It is a slow process though as you say.