At that height I'd plant them horizontally;

Dig a trench 3-4 inches deep. , take off all side stems and foliage, leaving just a tuft of foliage at the top of the plant, lay the plant down covering with what I call dirt, leaving that tuft free at that end. Water in well to get rid of any air bubbles.

A few days in the sun and that tuft will grow upright and make a nice new plant and the bare underground part will form new roots, called adventitous roots, giving the plant lots of roots for uptake of water and nutrients.

Carolyn

Lay on side.

dave

In zone 5 i would do as Carolyn suggests. In zone 5a i'll be trenching a few this weekend. A bit early but i have to take advantage of the long weekend and good weather. Taking some chances. My starts did better than expected and some started way early. Even the culls meant for the compost, and sat in a wet heap on the side of the potting-up bench for a week, ended up in pots.
So i have some extra to fool with.
You could try one or two down deep if that leggy tall... mark it as an experiment. Yet i find the trenching does best for my climate. Deep down my soil stays so cold and damp all season. Even in July heat.

Trenching (laying on side) ,as suggested , is one option.
I would plant it vertically, such that about 9" of top is exposed. AND place a stake next to it and tie it. It will be more secure this way, IMO. If you have more than one such leggy plants , try both ways and find out which way is better.

BTW: today I had one such plant (left over , without home for over a month). Maybe 16" tall. I just could not convince myself to compost it. I planted it in a pot such that about 9"(~) exposed. Obviously, I could not trench it in a pot.

But what about the WHY in all this? Going deep gives you deep roots in cooler soil, and the same amount of buried stem as if you trenched. Why would trenching be better?

You answered your own question - trenching puts the roots in warmer soil and digging deep into cooler. That may make a difference depending where you are located - I'd say zone 5 go for warmer, you probably get enough rain (or you water) so that the roots don't have to go deep to find water. Not that they won't grow deeper than your planting hole/trench anyway, but you want to make sure the buried stem gets plenty of water to grow the roots.

Part of the "why" is because trenching is easier, less work. Course how easy/difficult it is to dig a 12-16" deep hole depends a lot on the type of soil you are working with.

Part is also nutrient related since most of the amended nutrients are worked into the top 6-8" of the soil.

Part of it also depends on how deep your bed is. Many using raised beds couldn't go that deep. They may only have 8-12" deep beds.

Part is also the soil temp as already mentioned. If we wait for proper soil temps at 6" deep to plant then we wouldn't want to dig deeper into colder soil, right? Cooler soil may be of benefit in late July (depending on where you live) but it isn't a benefit this time of year in your zone. And you can keep soil cooler by mulching well when the shallow soil does become over heated.

So if the benefit to the plant is basically same - its stem rooting ability - why not trench?

Of course the optimal is for us not to end up with 18" plants to begin with. :)

Dave

You could try a perk test. Dig down 12-14 inches...a nice big hole. Should be easy if your soil is loose and amended. Pour in a gallon of water and see if it drains well. It may form a bucket and would give you very wet feet on your plants every time it rains/ watered. Ferns love constant we feet....tomatoes not so much. : )
My garden was put in '95. Raised beds that are never walked on, so not compacted. (occasional double dig)...i can easily dig 18-20 inches but a significant change happens at about 16". I think it is referred to as the 'pan' layer. (don't quote me, i tend to make stuff up)
But that deep soil, not mater if i dug to China, and added a hay bail, it would soon revert back to cold, damp, and constantly moist eventually. It drains well but never dry. That is just what my soil/climate wants to do with consistent weekly storms/rain then sun. Cool damp foggy mornings, hot afternoons.
Just a choice to make for a chance at a great crop of toms.

I think there are preferences. But either way the plant will survive and grow fine.
Op said his plant is about 18". If it was in a 8" pot ,probably had a pretty good root system. So you bury it vertically deep (leaving about 9" above ground) it will grow a secondary root system just below the surface.

The link below is one of my favorites, Back in the 20's and 30's a lot of basic work was done with crops, and I'm so glad this link is still available.

Go to the chapter on tomatoes and take a look at the pictures, notice the difference between a tap root structure and a fibrous one and which is best and how one gets either one.

Then see how deeply tomato roots with the desired fibrous root structure can go, as in how deeply, and then think of how many folks are not allowing for proper growth when using containers, raised beds, etc.

I can compare b'c for many years I only grew tomatoes inground, but then when I retired to where I am now I could only grow in a large raised bed, grow bags and large containers. But was also growing plants at another local place, actually two of them.

And there were times when I was growing out many of the varieties I used to grow inground here at home, and yes, I know it's not a direct comparison in the same season, but I do feel I have the experience to tell the difference.

Carolyn

Here is a link that might be useful: Root development

The roots can go deep (this article said 3 ft) so a deep container or in-ground is best, but I noted this:

" In the surface soil, usually below 2 inches, roots arose in great profusion. The adventitious root system, i.e., roots arising from the buried stem, was making a vigorous growth. In the seedling stage the young roots grow out from the stem in distinct vertical rows which correspond with the position of the fibrovascular bundles within the stem. But after the plant becomes larger and older they arise from all sections of the stem below the soil surface. From 18 to 33 laterals clothed each inch of taproot. Like the adventitious roots, nearly all of these took a horizontal course. Although most of them were only 1 inch or less in length, many were 0 to 9 inches long. Thus the surface soil for nearly 1 foot on all sides of the plant was thoroughly ramified with rootlets. Even beyond, to a maximum distance of 2 feet, larger laterals were found. A few had reached their greatest spread from the taproot and started to turn downward. Only rarely did a root pursue a downward course in proximity to the taproot."

Does this indicate that it is best to trench 2" deep and lay the stem down when transplanting a leggy seedling so as to encourage adventitious roots?

Edit - sorry, I misread that as "within 2 inches" not "deeper than 2 inches" so now I know why Carolyn said trench 3-4" deep. But to investigate further the OP's question "why?", is it best to trench shallowly (though not as shallowly as I suggested!) to encourage the adventitious roots? Do they not develop as well at depth (and how deep)? And I'm wondering if this has to do with surface watering - I know they develop in moist conditions.

Sorry I am raising more questions not pertinent to OP's situation, but I am wondering in a drier hotter environment whether burying deeper would be better (assuming there is some ground water, as well as being cooler), or if it is always better to trench (and make sure the soil from say 1-6" is kept moist, by drip irrigation and mulching in those arid environments)?

This post was edited by ajsmama on Fri, May 23, 14 at 18:09

What do you do when planting tomatoes that are, say, 18 inches tall, dig straight down to where you want them, or dig a long hole and lay them on their side?
Well had (and still have) some tall ones. These will also fall over, go boom, if left unsupported. So I "trenched" 5 of them yesterday and will employ same treatment on others today. These were around 32" in height and are Wes cult which is rather limp anyway. Made too acute an angle on one and crimped main stem... this, I think, is to be avoided. Rather have the damn thing intersect soil line at an angle greater than 90ú to the plane of soil level than crimp stem. I suspect plants (that need it) know whence light is emanating. I will add on this method the advice to avoid stepping on area (least for a bit) where "horizontal" segment of stem has been buried.
Anyway, glad I ran across this discussion at this time.
Reggie

Reggie, follow Carolyn's direction and leave the plant at the acute angle. It will straighten itself within 48 hrs.

They recover from crimps - actual breaks (even if not completely through) are tougher on them. I broke 6 this year potting up and they are looking still perky by stuffing the broken top down as far in moist potting soil as I could w/o breaking again. Though of course it will take quite a while for them to grow some good roots and get hardened off. Too bad 3 of them were BWs.

In zone 7, our experience is to go straight down as far as the depth of loamy, amended soil.

After tilling each year, we're talking average of 12 inches. So in the case of 18 inches, we'd strip the stems and leaves, allowing 6 inches of plant above ground.

Works better (and more easily) for us.

follow Carolyn's direction and leave the plant at the acute angle. It will straighten itself within 48 hrs.
Yea, followed advice and put a few in at a rather obtuse angel wrt plane of soil line. This is almost a necessity for tall and rather thin plants. Was considering topping the tall boys. Soil is very good here with about an 8-10" horizon to the junk. Toms I slapped in yesterday with trench planting method look OK today. I do not like the tall seedlings... just happens with some. Trying to keep the best ones I have.
Reggie

Planting vertically deeper and horizontally shallow have their specifics.
If you are gardening in a HOT climate, that temperature hover over 90s for weeks and months, with little or no rains, perhaps you are better off planting deep vertically. Trenched tomato will grow mostly shallow horizontal LAZY roots. Because the soil surface dries much quicker, then they need to be watered more frequently, that is fine if you do it or have a drip irrigation.
JMO

Trenched tomato will grow mostly shallow horizontal LAZY roots. Because the soil surface dries much quicker, then they need to be watered more frequently, that is fine if you do it or have a drip irrigation.

&&&&&

Sorry, cannot agree/

Trenched plants send out adventitious roots, as was described and quoted from the article in a post above, and so every few inches one gets those roots started from the main buried stem.

They keep on growing and expanding to form a tremendously huge fibrous structure, bigger than any plant planted vertically, and so have a much greater capacity to adsorb water and nutrients than does any SINGLE plant that was planted vertically,

You'd water the trenched ones, if needed, just the same as you would single plants and no need to worry about the surface drying out any more than the surface drying out where single plants are growing vertically,

Hope that helps,

Carolyn

Trenched tomato will grow mostly shallow horizontal LAZY roots. Because the soil surface dries much quicker, then they need to be watered more frequently, that is fine if you do it or have a drip irrigation. Hold on Pilgrim. This may be done by motivation caused by necessity. In my case (for a few) the damn things are too tall and too thin to try to plant vertically. This is a mistake for me... too tall and too cold to put outside when then were shorter.
Reggie

Reggie - I'm in the same boat, the indeterminates I started 3/29 have been outside for 2 weeks now, they were getting leggy inside and I haven't had enough deep pots to put them in, did do a couple in quarts just b/c they were getting so tall. Hope to plant out the end of this week after Wed night's low of 45.

The ones (mostly determinates, but can't attribute it to that since some indeterminates too) started a week later are still under lights and look very good, but they're still in 6-packs and unless I can get them potted to 3-4" pots ASAP, I'm afraid by the time I get them hardened off (rush to do it and plant by 6/7, when they're 2 months old?) they'll be leggy too.

All this rain isn't helping.

Roots aren't lazy or industrious. They grow the way they do because of soil conditions - porosity, availability of water, nutrients, etc. People grow tomatoes hydroponically, so the horizontal-vertical root discussion is moot. Do what you can do with the soil you have.
BTW - tilling is not beneficial to soil.

Sure , We are here to disagree sometimes.

In support of what I said , here is a direct quote:

" University research in Alabama and Florida found that planting stems straight down with the root ball in deeper (and cooler) soil can improve fruit set in hotter weather. It's probably best to do this in southern areas and trench plant in northern areas (for more warmth).""

And here is a quote from my comment:

""f you are gardening in a HOT climate, that temperature hover over 90s for weeks and months, with little or no rains, perhaps you are better off planting deep vertically. ""
And here is an image of trenched tomato That I was talking about

YMMV

This post was edited by seysonn on Sun, May 25, 14 at 21:15

Can't say I have ever seen a 'lazy' root. What does one look like so I''ll be sure to recognize them?

tilling is not beneficial to soil.

Not sure how that is relevant to the current discussion but it depends on the soil. Beside my raised beds that don't need any tilling, I also have acres of very rocky, glacier scrub type soil that make up most of my in-ground gardens. And an annual tilling has done wonders for them.

Dave

Can't say I have ever seen a 'lazy' root. What does one look like so I''ll be sure to recognize them?
%%%%%%%%%%%%%%%%%%%%%

It is just a figure of speech !

""A figure of speech is the use of a word or a phrase, which transcends its literal interpretation. It can be a special repetition, arrangement or omission of words with literal meaning, or a phrase with a specialized meaning not based on the literal meaning of the words in it, as in idiom, metaphor, simile, hyperbole, personification, or synecdoche. Figures of speech often provide emphasis, freshness of expression, or clarity.""

GOT IT ?

Nope, I don't got it. (smile)

You may have turned your word lazy around to indicate it's a figure of speech, but when referring to lazy tomato roots, that's something quite different IMO.

Whatever!

Carolyn

I don't got it either. Even figures of speech have attached connotations and should be used accordingly. The word "lazy" has lots of negative connotations attached.

Unwilling to work or use energy, indolent, inactive, lack of performance, idle, slow, sluggish, etc.

So exactly what is it about these roots that make you think slapping that label on them is warranted?

Dave

I used the word "lazy" metaphorically.
We know that literal meaning of adjective "lazy" cannot be applied to plants or plant parts.

Just look at further usage of "lazy"

"""TheFreeDictionary.com
Resistant to work or exertion; disposed to idleness. 2. Slow-moving; sluggish: a lazy river. 3. Conducive to idleness or indolence: a lazy summer day. .."

LAZY RIVER, LAZY SUMMER DAY ????
Well ! still don't get it ?

Carolyn, that book is my favorite too. The pictures never fail to captivate.

OnT - I would go deep, but here dry heat is the threat.

(Per our favorite book, a mature plant will have roots all over the place. In warm soil probably not a big deal either way.)

This post was edited by johns.coastal.patio on Mon, May 26, 14 at 14:37

Yeah I get what you are trying to imply about the adventitious roots that develop when the plants are trenched in - that they are supposedly resistant to work or exertion; disposed to idleness. 2. Slow-moving; sluggish, etc.

But since none of that is true anyway then I suppose it doesn't matter if you don't explain why you are making that claim.

Dave