Amending individual planting holes is a practice that has fallen out of favor and is no longer recommended. There is actually a great deal of evidence to support that good drainage is compromised due to soil interface issues with amending and that roots are less inclined to spread well if they encounter different soil structure. The recommended practice is to dig a wide planting hole and backfill only with the soil that was removed. You can mulch over the soil with whatever you wish. If poor drainage is a consideration, amending is even more of a concern, as you can easily create a bucket effect, where moisture will pool in the planting hole and not drain out or percolate down promptly, resulting in root rots, lack of oxygen and death. In this case, a wide and shallow planting hole is recommended - leave the top inch or two of the rootball above the soil surface and mulch up to the edge.

If you absolutely need to amend, do so over as wide an area as possible, like an entire planting bed.

You can find gardengals information at the U of Ga, UC Berkley, U of Okla, Fla and Ohio plus many state nursery associations. Call landscapers and you'll find most don't know this.

Many of the amendments that were formally recommended will turn anaerobic under ground leading to either a alcohol or ammonia by-product. Water is usually important though, most plants are either grown in pots with plenty of water or they are dug cutting off roots.

I did a test, buried "recommended amendments" then came back later and lifted this area, found a rotten odor. I'm like many people presented with new research, I had to prove it to myself. My spouse still insist on putting a little something in the planting hole, "feels" like it helps.

Amending your soil is a very good idea, but simply amending the planting hole IF you have heavy clay soil is not. Amending just the planting hole in clay soils will result in a small are that water could flow into very easily but will not be able to flow out of and then yout plant will drown.
where will this "top soil" come from? What is this "top soil"? "Top Soil" is just the top 4 inches of soil scrapped off someplace nad could be the best stuff in the world to grow plants in or it could be simply some black sand. Most people when they think of "top soil" think of loam and those terms are not synonymous. Far better for you would be to simply add organic matter to your soil than to spend money on something as questionable as "top soil".

Thankyou for the responce. The soil in my yard is nice and dark, as the place used to be farm from 1860 on. If I dig a hole anywhere in my yard, I have about one foot of dark soil, then pure sand. I have a large bin of compost crawlimg with worms. So am I better off to just dig a hole, save the top 4" add some of my compost and call it good? Thanks

Skip the compost in the hole. Use it on top after planting.

Filix, whatever plant you intend to put into the ground, it has to grow outward into the surrounding soil and be nurtured by it.
Some plants, such as trees, with their large root systems, do require they get their food from the soil outward from the hole you just dug. To give them a hyped soil right away, then may give the roots encouragement to grow more quickly than maybe they should, then are confronted by what is out there. Perhaps it is clay, perhaps it is a sandy soil. Whatever it is, the plant must learn to take its nourishment from the surrounding soil---not from how you might amend it.

Small plants, with their very shallow rooting, may indeed need encouragement early on and amending it right away can help.

The plant's roots has to though grow in the soil that is there..plus any percentage of amending which should not be more than 25 to 30%. You are advised to mix with the present soil any amendments you choose to add....whether that be compost, peat moss, sand, loam, manure or topsoil.

I have a friend who adds dryroots and peat to everything he plants. I can see the logic in that it has too grow in the soil thats there eventualy, unless you dig up the whole yard. Im going to do alot of flowers in containers next spring why do they tell you to use a soiless mix, because there are disease in top soil or loam. Even compost. That doesnt make any sense to me. You mean I cant just sift some nice top soil and compost then put that im my contaners? it might kill my clematis. Artifical stuff is better?

"The soil in my yard is nice and dark, as the place used to be farm from 1860 on. If I dig a hole anywhere in my yard, I have about one foot of dark soil, then pure sand."

Its not polite to brag! ;- )

harumpf...

I don't think there's a single answer to this question (or most other gardening questions). I can think of examples where amending the planting hole with dense nutrients is deadly, and others where it is a necessity for the plant's success.

Put a bunch of compost in the backfill when planting a Miscanthus, and you'll get a lax falling-over grass. Do it with a Tomato transplant, and you'll get a much healthier plant than if you merely topdress with compost.

I plant tomatoe transplants every year in a 1 ft deep post hole 'and back fill with 75% compost and aged goat manure and 25% top soil not from that hole,cage it and let it grow .works great for me.

filiz, it sounds like you have something close to sandy loam so you can either add compost to the planting hole or just lay that compost on the surface as a mulch. Either will work, in your instance, equally well.

filix, planting in containers is a very different situation than planting in the ground. Containers offer a closed environment - there is very limited opportunity for drainage and for oxygen to enter. Soilless mixes or those specifically forumlated for containers have highly increased porosity to enhance and encourage drainage and to allow lots of space for needed oxygen. Garden soil is simply too heavy, the pore space is smaller and drainage is slower, so you are unlikely have the same success using this for container growing, specially if it is anything long term. The constant watering needed for container planting also tends to compact garden soils used in this manner. A visit to the Container Gardening forum may be helpful - there is lots of great info there and tips on making your own potting mixes.

Cropped plants - like tomatoes - do benefit from a well-amended soil but in many cases folks who are growing these types of plants have spent time and effort preparing an entire planting bed (or more) to accommodate them and other veggies. Again, this is far preferrable than amending an individual planting hole. You still run the same risk of encountering problems with drainage issues and you would with root development as well, except for the fact that these tend to be very seasonal crops and do not develop the far reaching root systems of more permanent plantings. When planting trees, shrubs or permanent additions to the landscape, avoid amending individual planting holes. The research supports better growth and establishment in non-amended planting holes.

Thankyou for so much help.

luvorganic- first, if you don't have clay- it's not as much of an issue. Second- it's not as much an issue for annuals either. Third- in that medium- you could grow a tomato plant in a pizza box.

For perrenials, trees, etc with extensive roots- it may matter.

"..in that medium- you could grow a tomato plant in a pizza box."

Pablo, you might be interested in the chapter, linked below, on Tomato Root Development.

The entire document is interesting, even though it was written in 1927.

Here is a link that might be useful: Tomato Root Structure

Donn- that is pretty neat stuff. Give them room and they'll explode like that.

Confine them- and the roots will go where they can. The SFG and container folks have shown that the right planting medium can make a smaller than optimal planting area produce anyway.

I plant in wide beds that aren't quite square-foot arrangements, but definitely don't give the roots that much depth potential, and are "crowded" by conventional standards.

donn
very interesting article' I'm leaning toward 2ft deep holes now in place of 1ft. my tomatos had good root structure this year. but from that article roots go deeper than 1 ft . the only reason i dig post holes is ive got clay soil and lots of big rocks. but i get great results'and thats what counts. have a good afternoon