I didn't know plants could shed!

July 15, 2009 10:52 AM

I've got a couple cherry tomato plants on my windowsill that have been growing like gangbusters -- there's even one little tomato that's JUST starting to turn red. But -- they're also dropping stems off the main plants at an alarming rate. What's happening, and how can I stop it?

Some of the stems that are dropping off look like they're drying up first, and some aren't -- it almost looks in a few cases like someone's come along and just broken the stems where they connect to the main plant, and then just left them there.

I checked online for common tomato diseases, and this description sounds closest to what is happening -- but still not quite accurate; that kind of wilt sounds like a more gradually-spreading thing, and with my plants, the stems are just breaking off spontaneously. I'm even seeing new growth in a couple places where old stems broke off. The fruits are also coming in fine, and don't seem to be affected.

I did see some bugs crawling around on the fruit a few days ago -- it looked like something had started spinning a web around it, and tiny flies were crawling around in the webbing, but I hit it all with a shot of some pyrethium-based pest spray and that killed 'em all. The fruit looks just fine, and went on its merry way turning red again. I didn't recognize the bugs - they were the same size and shape as whiteflies, but...they were black instead of white.

Might those bugs be the cause? Or might this be over- or under-watering? Too small a pot? (I have three plants in a biggish tub -- I re-used the tub from a 20-pound tub of kitty litter, so it's about 2 feet tall, and 18x10 in length and width -- but because there's three of them in there I'm wondering if they're a little crowded.) Is the fact that there's new growth and the tomatoes are fine a good sign, and maybe this was just a temporary thing? Is my cat maybe poking around in there and snapping things?

All advice welcome. Thanks.

posted by EmpressCallipygos to home & garden (29 comments total)

That is a pretty small container for such large plants. Tomato plants can be beasts. An Earthbox which is much larger is designed for two plants.
posted by caddis at 10:59 AM on July 15

I did specifically pick a variety that was suitable for smaller containers -- at least, that's what it said on the seed packet -- and asked the gardening store if I could get two plants in that size container. He did allow that bigger was better, but two should be fine.

(However, when I picked the two seedling peat pots I was going to keep, they each had two seedlings in them, and I felt guilty about uprooting one of the two in each one so I just let them grow. That is my own tender-heartedness, and I own it.)

I do have three plants in there, but one is considerably smaller than the others. Would uprooting that one help at all?
posted by EmpressCallipygos at 11:13 AM on July 15

I have an Early Girl tomato in a pretty large pot with the same issues, bugs and all. No idea what's causing it, but the plant is basically dying and the tomatoes that are on there are just ripening without getting any larger at this point. Sorry I can't be of more help, but I'm pretty curious as to what sort of responses you'll get.
posted by booknerd at 11:36 AM on July 15

Tomatos often need to be supported. As I'm understanding what you are describing, I wonder if the weight of the vegetation is causing the breaks. Get some sticks or stakes and tie things up to provide some support.

When we lived in an apartment, we did some crazy density planting in small window boxes, so I don't think the size of the planter is necessarily your issue.
posted by Good Brain at 11:46 AM on July 15

This is a tough one, but two things occur to me. 1) It's possible that it's a condition issue -- maybe the container is too small and the plant is rootbound, or maybe they're getting too little water. (Too much water would probably show up as a yellowing of the leaves.) Or, perhaps the plant isn't getting quite enough sunlight, and is therefore kind of spindly? If so, and if the stems are skinny, the weak branches might be snapping under their own weight.

2) It's also possible that it's just totally normal "shedding," as you call it. Are the stems that are breaking off being crowded out by suckers? (Look at the crotch, so to speak, of a few branches. Are there little stems sprouting there? Those are the suckers.)

I don't think it's likely to be fusarium/verticillium wilt since the plants are a) inside, and b) in potting soil. (Though it's possible that you bought infected plants. That'd be pretty rare, though, given all the growth controls imposed by commercial nurseries.)

In the absence of another diagnosis, I'd regularly pinch out all the suckers and see if it doesn't make a difference.
posted by mudpuppie at 11:51 AM on July 15

Mudpuppie: I'm jumping on your comments to see if we can diagnose this (you sound like One Who Knows).

* It's sitting in an east window with a very deep sill -- it gets sunlight from dawn to about noon. It's been growing like mad up until this point. I've had good luck with the herbs I also grow on the same windowsill -- rosemary and sage -- which have also been going like mad (I've referred to the sage plant as "The Sage That Ate Sandusky"), and I know those two need lots of sun, so if they're doing good, I assume that's a good endorsement for the sun exposure in general.

* There MAY be a water issue at that -- I'm used to my herbs, which are woodier and take less water; I've had to remind myself that "this is a tomato, not a rosemary bush" and I may have underwatered a bit as a result.

* I haven't noticed any suckers growing before the stems drop off; only after they have. I'll take a closer look, though.
posted by EmpressCallipygos at 12:15 PM on July 15

The water issue is tricky. Tomatoes don't actually like or need a LOT of water. When they're in the ground, they only need to be deep-watered once a week or so. When they're in containers, where the soil can't retain as much water, that's a hard balance to strike.

Six hours of sunlight is good indeed. Are the stems sturdy? Are they, say, bigger around than a pencil?
posted by mudpuppie at 1:14 PM on July 15

Three plants is really crowded for a pot that size. I'd suggest growing just one plant in the container you described. Tomato plants have a pretty big root network and do better with plenty of space.

The bugs you described are most likely spider mites. Interestingly, that article suggests that outbreaks are often caused when insecticide use has killed off their natural predators. I typically use insecticidal soap or wipe down the leaves with a damp paper towel to get rid of mites and aphids. It's not foolproof, but it works well enough.

I'd say it's sort of generalized stress. Tomatoes like a fair amount of water, lots of sun, and a good bit of space. If you're constraining all three of these things, the plants aren't going to thrive and will be more susceptible to insect damage and diseases. Fusarium/verticulum wilt is possible, and spider mites can spread disease, but with so many additional stressors, it's tough to say.

Few other questions:

1. How big are the plants?
2. Are they determinate or indeterminate? Variety?
3. Are you using potting soil or dirt from outside?
posted by electroboy at 1:17 PM on July 15

You know, for some reason I didn't see that there was a cat factor listed at the end of your question. This is also a distinct possibility if the plant looks otherwise healthy.

One question I forgot to ask: Do the leaves turn brown or yellow before the stem snaps off?

(And the bugs you're seeing are probably fungus gnats. They're harmless, but annoying. You can cover the surface of your soil with 2 inches of sand; since they won't be able to get to the soil surface, they'll be sad and will leave you. You can also use yellow sticky traps, but they're less sightly.)
posted by mudpuppie at 1:19 PM on July 15

I'm going to disagree with the spider mite theory based on the fact that they were black and were the size of whiteflies. Spider mites are smaller than whiteflies and are red.
posted by mudpuppie at 1:21 PM on July 15

Well, they're not necessarily red, and can be dark brown-ish, and I'm thinking the webbing is from spider mites. Could be both though.

Either way, insecticidal soap or wiping off the leaves is probably a better control method than insecticide.
posted by electroboy at 1:31 PM on July 15

All unexplained phenomenon in my house are blamed on the cats. If yours are anything like mine, poking around in an unattended box of fun leafy things is a definite possibility. I think this might be the way to go. If it turns out to me a temporary thing, I think you have your answer.
posted by cgg at 1:49 PM on July 15

Answering a bunch of questions here:

* The main stalks on two of them are definitely big around as a pencil. The third is slightly slimmer.

* I'm using potting soil. I don't trust the dirt from outside (I also don't have a yard, I live in a 4th floor walkup in Brooklyn so the only soil I could get for free would require breaking into a vacant lot alongside the BQE and God KNOWS what exhaust fumes would have done to it by now).

* I'd have to check the exact variety, but they are a cherry tomato that the packet said was especially suited to container gardening. The packet even said that they didn't need to be staked, as it was more "bushy" than tomato plants tended to be. This has mainly been true, although one stem is leaning over some with the weight of the tomatoes. I just "braced" that by leaning it against the window screen.

* Speaking of which -- I have the glass part of the window open, and the screen down, so I can catch a breeze. They're sitting against the screen.

* They're all about 2 feet tall.

* It's hard to tell whether the leaves turn yellow before the stem's snapped -- usually I notice the yellow first, but then when I look at those stems, I see that the stem has already snapped, so it's hard to tell which part came first. It looks like some of them are yellowing first, but I've seen some green stems snap off as well.

* I hadn't used ANY kind of insecticide or pesticide until I noticed those bugs. I haven't since, as there hasn't seemed to be any since.

* One other thing I DID spray on them once, however, was some bitter apple as a cat deterrent (I caught him tentatively trying to nibble one of the leaves once).

* For all my plants, I try to water until I see it coming out of the drain dish at the bottom. But sometimes I've gone a little over a week between waterings; the rosemary can get away with that, and I keep forgetting the tomato may not.

* If we're lucky, I may be able to pick the first cherry tomato tonight and see how that held up (i.e., it may look pretty, but be weird colors inside, which I'm sure would indicate some other problem).
posted by EmpressCallipygos at 1:49 PM on July 15

bitter apple as a cat deterrent

Ooh, new theory! *raises hand*

The first or second ingredient in bitter apple spray (which I apply to my ankles literally first thing every morning because of my little ankle-eater) is alcohol. This could have dehydrated the foliage that it touched, causing it to wither and release. (The 'snapping' part is weird, though. I'd expect more of a slow wilt and detachment.)
posted by mudpuppie at 2:31 PM on July 15

The water issue is tricky. Tomatoes don't actually like or need a LOT of water. When they're in the ground, they only need to be deep-watered once a week or so. When they're in containers, where the soil can't retain as much water, that's a hard balance to strike.

mudpuppie, I don't understand your assertion that tomatoes don't need a lot of water. I guess it depends upon what you mean by "a lot?" They don't like to sit in wet soil, certainly, but they need steady, even watering and good drainage. All that fruit is mostly water, after all.

EmpressCallipygos, for my cherry tomatoes, I've got one plant each in 5-6 gallon containers. Lots of drainage holes drilled into the bottom, potting mix. They get watered every single day.
posted by desuetude at 2:32 PM on July 15

Every day seems excessive to me. I'm not growing any in pots this year, but previously I'd do every other day, or three days a week. Worked pretty well for both tomatoes and eggplants.

Pencil sized at two feet tall seems a little thin. Sharpie sized would probably be more appropriate for a healthy plant.

I missed the cat part before. The snapping sounds like cats. Cats are jerks.
posted by electroboy at 2:44 PM on July 15

they need steady, even watering and good drainage.

Steady and even, yes, but not frequent. They do best with long, deep soaks on a regular -- but not frequent -- basis. Like once a week. This encourages their roots to develop and to dig deeper.

Also -- and there are varying schools of thought on this, I'm sure -- but it's also advised to stop watering entirely when fruit is ripening. This forces the plants to concentrate the sugars in the fruit. (Or something. I'm not about to try to explain it botanically. Where's oneirodynia when you need her?)

That's why their being in containers is tricky. Obviously, you can't curtail watering altogether, because they won't be getting it from the depths of the soil, like they would if they were in the ground.
posted by mudpuppie at 2:48 PM on July 15

Container gardening simply requires different techniques than in-ground growing.

Empress, I wholeheartedly and enthusiastically recommend McGee & Stuckey's Bountiful Container, which I've found to be invaluable for advice specifically for growing edible plants in containers.
posted by desuetude at 3:32 PM on July 15

Okay! Now that I'm home and I can look at the damn thing, here are some more detailed...details.

* Two of the plants are actually a little thicker than a pencil -- not quite at a Sharpie yet. Somewhere in between.

* A second fruit is starting to turn red.

* All the stems that have dropped have been lower down on the plant, and there is new growth in most places where things have dropped off. The top part of the plant seems to be doing okay.

* The exact variety I have is the "Vilma" -- according to the seed packet it says:

"No support, pinching out or side-shooting required. Height: 20-24 inches. A determinate compact and bushy variety specifically bred for pots and containers."

If any of that helps, there it is.

If it would help to split them up into different pots -- is it safe to transplant one of them at this stage?....
posted by EmpressCallipygos at 5:51 PM on July 15

Once a week watering for tomatoes crammed into a too small container? You need to water much more. The soil should stay moist about two inches down all the time. You might need to water every single day in such a small container, well you would if they were outside in the heat. You might be able to get away with less inside. Tomatoes do not like to dry out. If they do you will get blossom end rot, and then when you water to catch up you might get cracking. Tomatoes want a constant steady supply of water. Since you were not getting too many hits from people with experience I did some searching and anecdotally there is some evidence that a too small container can lead to blossom shedding, and that keeping the water level up remediates that somewhat. Don't add fertilizer, or at least only very minimal amounts. This variety really does seem suited for smaller containers, but even so three plants in that container seems a bit much. Keep them watered without over watering to keep them as happy as possible.
posted by caddis at 6:08 PM on July 15

Ooof, splitting the plants is risky. Can you move the whole shebang into a larger container?

It ain't a pretty pot, but I have my larger varieties in 18-gal storage containers from LowesDepot. They cost like $7. I drilled a lot of holes in the bottom for drainage. You'd need a big-ass something underneath to collect the water, of course.

Anyway, I think some very dilute fertilizer might help (like perhaps half-strength of what is recommended), since there's not enough soil to supply enough nutrients. Worm casings would be ideal, seaweed is a miracle drug too, but regular ol' Miracle Gro for tomatoes works, too.
posted by desuetude at 7:26 PM on July 15

The problem isn't finding a big container -- the problem is finding a place to PUT a container that big. Can't go on the floor -- it wouldn't get the sun. Can't go on the windowsill -- the sill isn't big enough. Can't go on the fire escape -- that's against the law now. Can't go in the yard -- don't have one.

Since you were not getting too many hits from people with experience I did some searching and anecdotally there is some evidence that a too small container can lead to blossom shedding, and that keeping the water level up remediates that somewhat.

That's well and good, but it's not the blossoms that are dropping off, it's the stems.
posted by EmpressCallipygos at 7:53 PM on July 15

The stem thing is very strange. The only other thing I can think of is possibly lack of potassium, as that affects how well the plants set fruit. Typical general fertilizers are usually balanced, 10-10-10 type stuff. The excess nitrogen can encourage good plant growth, but without sufficient potassium you'll have difficulty setting fruit.

I'm still going with general stress due to overcrowding, less than optimal light and possibly underwatering. Fix those things and you'll probably be ok. Maybe add some lime (for calcium) and potash (for potassium), but no more than a tablespoon of each.
posted by electroboy at 8:16 PM on July 15

I'm confused by what you mean by stems- do you mean leaves are dropping off? If they have blight they will turn yellow first. Same with a nitrogen deficiency. I think your cat might be rubbing them off if that's not the case. Green leaves don't just drop off. Look for cat fuzz stuck to your plant. The other issue may be light, but there's nothing you can do about that right now unless you want to visit a hydroponic store and pay big bucks for light.

Adding lime now won't do anything- you've got to add it to the soil 2-3 months before the plants need it for it to be available to them. Potassium deficiency in tomatoes manifests as a scorched appearance on recently matured leaves. Are your tomatoes a healthy green?

As far as watering goes, I always let tomato plants with fruit go to a slight wilt before watering. Like mudpupie says, this concentrates the sugars in the fruit. They will be smaller, but taste better than big watery tomatoes. ( Some people freak out about this because it can cause tomatoes to crack, but I've never had that problem. It really depends on the type of tomato.) It also stresses them out enough to cause them to flower more: plants that think they are near the end of their life do everything they can to reproduce. So you never want to stress basil or lettuce, because you don't want fruit. Tomatoes are another story.

Water until it comes out the bottom, every time. Then let the top two-three inches dry out if you're not ready for full-on tomato stressing. I used to water my five-gallon tomatoes that were on my warehouse roof in full sun and wind once a week, and the tomatoes were fantastic. Be certain that water isn't just running around the soil and out the bottom- the pot should feel heavy.

It is too late to divide them now.
posted by oneirodynia at 7:43 PM on July 16

I'm confused by what you mean by stems- do you mean leaves are dropping off?

More like branches. And new growth is coming in at the places where the branches have dropped off.
posted by EmpressCallipygos at 8:33 PM on July 16

OK, so not leaves at the base of the plant, but branches? That sounds like cat shenanigans to me.

Sorry if this is an elementary question, but are you certain it is where the stem is branching, and not big leaves? Tomato leaves can be quite big, with 5-7 or more leaflets. They attach to the stem of the tomato at a node, where new leaves or fruiting branches can grow out. The base of the leaf will be somewhat wider, and have a slight depression or notch on the topside where it attaches to the plant. Branches don't have the notch, and they will have more leaves coming off of them.

I'm asking because I'm unsure from your description what exactly is going on. It's not clear if your leaves are changing colors before they drop, which would indicate disease or deficiency. And tomatoes don't drop entire branches unless there is some sort of mechanical injury; they would drop leaves first in case of deficiency. Without pictures it's really hard to make any sort of diagnosis in this situation.

If the lower leaves are not getting enough light, they will drop because they cannot make enough food to sustain themselves. That's not a huge deal- it is how the plant survives. If your plant isn't getting enough nitrogen it would also drop lower leaves, but you'd see a definite yellowing of the older leaves before that happens. Other nutrient deficiencies will also have a visible manifestation of some sort- if you're not seeing them at this time, there's not much point in fertilizing now, especially with determinate tomatoes that tend to set just one crop. The one thing you might not see now is calcium deficiency, but there's nothing you can do about it once you have fruit set- 90% of the calcium the fruit will take in has already occurred by the time the fruit is the size of your fingernail. If it wasn't there to begin with, you can't change it now.

Anyway, I think some very dilute fertilizer might help (like perhaps half-strength of what is recommended), since there's not enough soil to supply enough nutrients.

You can do this if you want. Like I said, it may not help because I can't tell if you are having deficiency issues or not. I'd be very wary of adding nitrogen because if that is not actually the issue, you don't need more leaf growth at this point because your plants can't support it in the situation they are in. (At any rate, it's not really accurate to say you don't have enough soil to supply nutrients because it is less about the amount of soil, and more about the type of soil, the receptor sites it has -organic matter has a lot of receptor sites that hold nutrients, so does clay- what was put in it to begin with, and whether the pH is allowing for uptake of nutrients.) Again, if you are not seeing deficiency symptoms, with the limited sun and space your tomatoes have, fertilizing them may just cause more problems. Excess nitrogen in soft new leaf growth tends to attract pests and disease- they know it is there, and they want to take it up themselves.


Honestly, if you aren't seeing yellowing, or sick-looking plants, and your tomatoes are fruiting, I wouldn't worry too much. There are some things pertinent to your situation that may be causing problems, but you can't do anything about light or crowding right now. If it were my tomatoes and they were too crowded, I'd be removing leaves myself to get more sun into certain areas. You should probably pinch off a lot of the new growth that is coming in where the leaves have dropped off.
posted by oneirodynia at 10:09 AM on July 17

Adding lime now won't do anything- you've got to add it to the soil 2-3 months before the plants need it for it to be available to them.

I was thinking more for pH adjustment, rather than calcium, but on second thought, it's store bought potting soil, so it's probably fairly neutral anyway.
posted by electroboy at 10:31 AM on July 17

Sorry if this is an elementary question, but are you certain it is where the stem is branching, and not big leaves? Tomato leaves can be quite big, with 5-7 or more leaflets. They attach to the stem of the tomato at a node, where new leaves or fruiting branches can grow out. The base of the leaf will be somewhat wider, and have a slight depression or notch on the topside where it attaches to the plant. Branches don't have the notch, and they will have more leaves coming off of them.

I'm asking because I'm unsure from your description what exactly is going on. It's not clear if your leaves are changing colors before they drop, which would indicate disease or deficiency. And tomatoes don't drop entire branches unless there is some sort of mechanical injury; they would drop leaves first in case of deficiency. Without pictures it's really hard to make any sort of diagnosis in this situation.

Sorry this is confusing -- but the big reason it's not clear whether the leaves are changing colors is that there hasn't been any consistency as to whether they do or not. Some places, the leaves do change color. Other places, they don't.

The only consistent thing I've noticed is that this all seems to be happening lower down on the main stem -- nothing's dropped off from the top of the plants -- and that new sprouts/branches/leaves/things all are coming in at each of the places where the branches/stems/leaves/whatever have dropped off. Meanwhile, the top of the plant is sporting flowers and fruits, all in various stages of budding, blooming, fruiting, and ripening.

If the lower leaves are not getting enough light, they will drop because they cannot make enough food to sustain themselves. That's not a huge deal- it is how the plant survives.

There's a logic to this...right now it's getting about 7-8 hours of direct sun. Is that enough, or might that be too little? Should I be turning the plant more often, too?
posted by EmpressCallipygos at 10:45 AM on July 17

The more I think about it, the less likely it seems like a deficiency issue. Most potting soils have a reasonable balance of the big three nutrients right out of the bag, so as long as it's new it should be ok.
posted by electroboy at 10:46 AM on July 17