Growing a sweet potato vine, FAST

According to our school cafeteria, September or October is National Sweet Potato Month. Every other cite I find says it’s February, but whatever: it’s school, not the straight dope, so I don’t really need to fight ignorance there. The point is that the cafeteria director has given every classroom a sweet potato to partially immerse in water to grow a vine, and at some point in October, the class with the longest vine will get a treat that she makes.

And I want my second-graders to win. What’s more, they want it, too: we took a vote today, and the overwhelming majority voted Aye to my asking some experts what it would take to grow the best darn vine that we possibly could. (“Isn’t that cheating?” one child charmingly asked, and I rationalized away her worries forthwith).

So, experts, hold forth. What can I do to give our sweet potato the edge?

Some caveats:
-I won’t cheat. It’s gotta be within the rules (no transplanting vines or anything like that).
-I already have the potato partially immersed in water by three toothpicks, the standard method of growing a vine in this situation. I’m not going to use another potato.
-I’m unwilling to spend more than a few dollars on this, or to spend a whole lot of time on this. No grow lamps, in other words. A fertilizer might be all right.

We’ll treat this as a science experiment: I’m going to take the best suggestions from this thread and apply them to our main potato, and then I’ll get a control potato that just chills in its cup of water for the month, and we’ll see what differences there may be.

Gardeners use this powder that makes clippings sprout roots like crazy. Better root structure = more water sucking uppage = faster growth?

Somewhat off topic, but this story is just adorable. I wish I had advice for you, but I’m a definite gardening novice. I really want your vine to win, though!

Rooting Hormone

Cheap, easy to use and effective. Works great on cuttings, pretty well on tubers. If it’s whole, score the bottom third and moisten. If you’re growing hydroponically, concentrations in the water will need to be pretty high.

You can find it at any garden store, nursery or home improvement place.

Using hormone is a huge cheat. What a great thing to teach kids.

There are a number of germination/growth stimulants that can be used (here’s a list of possibilities). They include “natural” substances like vitamin C.

I don’t know how any of these stimulators would affect a sweet potato. One thing to keep in mind is that food potatoes are often treated with a growth inhibitor because consumers don’t like to buy sprouting potatoes. So if you added something to overcome this it wouldn’t, um, really be cheating.

I’d change the water that you’re suspending the lower part of the potato in often to help prevent rotting, and keep the potato in a dark place initially to promote rooting.

How so? It’s not like they are using anabolic steroids to win a baseball game.

Unless you want to leave it up to pure chance (and where is the science lesson in that?) the only way for one class to win over another is to for that class to research and apply the best horticultural practices. Since the use of rooting hormone to speed up rooting is a standard horticultural practice used by many gardeners, in my opinion it is no more cheating than if they used grow-lights or enriched their soil with compost. (Not to LHOD, I’m not recommending these things, just using them as examples.)

Rooting hormone is a a growth regulator for plants so it is the plant equivalent of a guy taking steroids. To me it’s still cheating and I think they should ask the person that offered to sponsor this contest. I’m not going to fight about this in this thread, so this is my last response. My point has been brought up for the teacher.

Plants grow long and thin when they don’t have enough light, or are growing towards a light. You could put it inside a cardboard tube (it should get at least some light). Warmth and humidity are good (a tube would help with humidity, especially with a clear cover), and maybe a bit of high-nitrogen fertiliser in the water. Another way to keep the humidity up is put the top half of, say, a Coke bottle over it. Give it something to climb, so that it keeps growing up. I can see an argument for pinching out side shoots to encourage the main shoot to get longer, OTOH, they will photosynthesize and help the plant grow. You aren’t actually growing it for very long, so I don’t think extra leaves will help much.

A natural rooting stimulant can be obtained from willows.

http://www.ehow.com/how_172766_make-rooting-tonic.html

I’m no expert on sweet potatos, but when I use rooting hormones to root new african violets, it causes lots and lots of root growth but hardly any stem or leaf growth for the first several weeks. So it might be counterproductive if you win with the longest stem, and not with the longest root.

Use fertilizer but be sure to follow the instructions and not overdo it; too much will kill it quickly. Any sort of garden or houseplant fertilizer of the Miracle-Gro type will do, though your first choice wouldn’t be one labeled Bloom … you want the kind higher in nitrogen for fast vegetative growth. Once the plant gets going it will use the nutrients very quickly so be sure to replace the water with fresh solution often.

The more light the better. Give it as much direct sun as possible.

If you decide to go for lighting, no expensive grow light is needed; if you put it under a fluorescent lamp it will thrive. Give it 24 hours per day if you can, and get the lamp as close as possible without cooking the leaves, within a few inches. If it’s a small desk or table lamp, move it frequently along the length of the vine.

If you want to go all out, see if several of the kids could bring in a fluorescent desk lamp (or perhaps the spare shop light Dad has in the garage) and arrange some sort of enclosure to reflect the light onto the plant; a cardboard box or a garbage can painted white on the inside or some white poster board … white is better than mirrors for this. The plant will like it warm, about 100 degrees or so, but be sure not to cook it.

Having a small fan blowing on the plant will help even if you don’t use lights; it prevents stagnant pockets of air, ensuring the proper oxygen / nitrogen ratio, and the constant physical movement of the plant makes for vigorous and sturdy growth.

Unless these things are specifically prohibited in the rules of the contest they are not cheating. If the contest is about growing the longest vine, this is the way to do it. Watching a plant grow doesn’t make for much of a competition, and only a minimal educational experience. Learning to take the steps needed to grow a large, healthy plant quickly … now there is a challenge … and a learning experience.

Have fun … play to win.

I would plant the tuber in a pot of soil rather than suspending it in water. I have done both (at the same time) and the soil-planted one grew much faster than the other one.

Watch out for sabotage.

This is more about getting it to sprout not root in the time frame given. Once it sprouts the roots will follow. The tuber will be supplying most of the food for growth. Strong light will give a shorter vine when it does grow. I would also go with the soil not a glass of water.

LHOD, Turble’s above post is good. I guess that the first thing I’d do to ensure best growth via Ma Nature is to have a good deal of the Sweet tater tuber to start with: the more you have, the more natural food stores the vine has to use for growth. The balance would be to limit growth to one “eye” sprout for length, not multiples for bushiness, and to change the water to avoid gankiness and rot of the tuber.

Sweet taters like long days of light and heat, and current conditions are cycling down with that, so amend as much as possible, the window with longest daylight and heat.

I’d agree with willow twigs as a natural rooting stimulant, just cut some up and add to the water, but, after a couple of days, change the water. I’d be curious if mineral water would have any benefit. A dilute solution of fish emulsion/kelp would be a natural fertilizer boost.

Ya might could ask your local hydroponic experts, the one that starts with"5th", a sister store to the one here in Chapel Hill, for more advice; they have good organic supplies.

Such a sweet project, really. I remember being wowed as a kid doing the end of a sweet tater w/ toothpicks project… it led to a love of horticulture. Best luck to your class!

Oh, and how about the class giving the tater a name? That might help them help in rooting (har) for it.

GROAN…:smack: