'Demeter' Low-Prune Greenhouse Cucumber Variety From Johnny's

This is 'Demeter', our new greenhouse cucumber with a unique, low-prune plant habit. Unlike many more conventional cucumber varieties, 'Demeter' produces substantially fewer side shoots, making it perfect for single-leader trellising in a greenhouse.

There are some important things to know, however, about the different stages of 'Demeter's plant growth and the nuances of this new variety, so we filmed this video to give growers an overview of 'Demeter' over a typical growing season at our research farm. We'll visit the greenhouse multiple times over different stages of plant development and try to give you as much information as we can to set you up for success with this exciting new variety.

Cucumber Plant Anatomy & Terminology

Here is a good example of your typical greenhouse cucumber plant. All cucumbers to some extent develop similarly, but greenhouse cucumbers have been bred to be very uniform about the way that they develop. In terms of terminology, we typically consider this part of the plant, the stem, to be called the internode. And the internode length is something that when selecting between varieties, we take a lot of consideration over. Then this part of the plant therefore would be the node and the node develops the fruit, a leaf, this tendril and a side shoot or a sucker. And that's going to be the same at every single node. Once you get the hang of identifying the different parts, pruning becomes very straightforward.

For greenhouse cucumbers, almost all of the varieties that Johnny's sells are gynoecious, which means that every flower is going to be a female flower. You can tell that it's a female flower because it has a tiny little fruit on there. That means that whatever else you do, you don't want to damage that because that's what you're trying to get at the end of the day. We also typically leave the leaves intact up until the point that they are touching the ground or close to touching the ground because we find that providing shade for the fruit is really important to avoid sunburn and scarring.

Pruning Greenhouse Cucumbers

The tendril is a little bit of a take it or leave it, depending on the situation. Some people can't be bothered or don't have the time to prune them all off and leave them there. And that's not really going to hurt anything until it does. And so the tendrils, as you can kind of see, like to wrap around things and they can wrap around the fruit and cause scarring of the fruit. They can wrap around the plant and kind of contort it a little bit, or more often what we often see is they grab the next plant over and you get a little bit of a mess. So I typically just snap the growing end off really quickly with my hand. That way nothing else is going to happen here.

You don't need pruners or scissors and you can move through really quickly. The most important thing to take off however, is this side shoot or sucker. Anyone who's familiar with greenhouse tomato production is going to be very familiar with suckering a greenhouse plant. It's basically the same process; you just go in and you just pop it right off.

If you get a little bit behind—and trust me, you probably will, we certainly do—you might find some of the suckers get a little bit big. In that case, it's much harder to just go in with the clean finger and pop it off like that and you might actually need some shears. But if you can do your best to keep up with the plant as it develops, you can just pinch it off.

Some other considerations are that the head of the plant, or the leader, is obviously the most important part because it's going to be what continues to grow up along the trellis. It's not uncommon for something to damage that leader, either an insect pest or accidentally snapping it when you're going in through harvest or pruning. And so I typically leave the suckers that are sort of on the first and second node down. For one thing, the node itself is a lot smaller and it's just harder to maneuver in here without accidentally damaging a fruit. But also if something were to happen to the main leader, you can actually develop one of these side shoots into the new leader and the plant will continue to grow.

'Demeter'

Here we are in our second greenhouse with another greenhouse cucumber trial that was seeded about 2 - 2 1/2 weeks later into the season compared to the one that we were looking at before. As you can obviously tell, these plants are a lot smaller and they're at a different developmental stage.

A lot of fruiting crops you can often think of in terms of vegetative, where the plant is putting on more vegetative growth, so leaves and vines. And then there's the more generative stage of plant development where the plant is putting on fruit. It is not as though cucumber plants will suddenly stop growing once they start producing fruit, but depending on the variety, that growth might get slowed down considerably. I mention that because with this variety, it's very important to understand the two stages. This is our new variety, 'Demeter', and the really special thing about it is that it requires a lot less pruning and a lot less maintenance compared to other similar greenhouse cucumbers.

When the plant has entered its generative phase, it produces far fewer side shoots, essentially none. And you can then focus solely on continuing to trellis the main leader and to harvest, but not have to spend all of the time going through and pinching off suckers. However, that's only the case once it is in the generative phase of growth. When it's still small and in the vegetative stage, it still produces side shoots and you are still going to have to prune it. We actually think this is a good thing because at this very small stage of plant growth, the plants are smaller, they're more fragile, they're more easily damaged, and making sure that you still have a potential new leader should something happen to the main apical meristem is pretty important.

As you can see, at this stage, we still have that classic plant architecture that we've been talking about. You have the leaf, you have the tendril, you have the baby fruit right there, and then you have the side shoot or sucker. And this plant is small enough that I'm not going to pinch the suckers off just yet, but you will have to.

Here we are in the same greenhouse that we started in about two weeks ago. And as you can see the plants are quite a bit bigger—cucumbers will really grow once you start putting on the heat and humidity and we've certainly had that. We've been keeping up with our pruning and so all we have at each node is a fruit and a leaf. As the plants get a little bit bigger and we start harvesting these fruit we're also going to prune the leaves up behind them so that when we start lowering the plants there's no leaves touching the ground and so there's a little bit more airflow which can help avoid disease.

As I said we have still had to prune this variety so far but we're at a pretty exciting transitionary point where the plant is starting to put on more and more fruit and is sort of turning from a more vegetative growth habit where it's mostly focused on putting on more plant to a more generative growth habit where it's starting to focus more on pushing out fruit. And this variety is pretty balanced like a lot of American slicers you can see there's only one fruit per node and it's a pretty big plant.

Some other varieties that we sell are more focused on being more generative, meaning that you're going to have two, sometimes three, fruit per node and with those you really have to make sure that you're providing a lot of fertility, that you're making sure that the plant doesn't get overly generative. And what we like about this variety is that it stays pretty balanced even in a low input growing environment.

We haven't pruned up here yet you can see there's still some of these suckers coming out but they're a little bit smaller than you would normally see in a plant like this and at this stage. And as you go up they start to become even less defined. A lot of times what you'll see for other varieties is even if the sucker is small, it's still a very clearly defined side shoot, whereas this is just kind of this funny little nub with a couple little growths coming out but not anything that is kind of a clearly defined side shoot. At this point if you want to you can still just sort of rub them off. But as this plant grows from here on out it's going to really start self-pruning those side shoots, really going to start stop putting them out to begin with. And you're going to be at a stage where you can just focus entirely on harvesting and not on all of the labor that it takes to keep the plants pruned.

It will continue to put out these tendrils which will very likely have to continue to get pruned though with obviously less frequency than the side shoots. Again, I just snap the growing tip off and that's the end of it. If they are helping the plant stay supported like this one where it's just wrapped around the trellis line, I'll snap it here so it doesn't girdle the top of the plant but otherwise just sort of leave them there.

I think at this point the best thing for us to do is show you what happens in another couple of weeks with no pruning and what the plants look like.

For the sake of one of the trials that we're working on, here's an example of some greenhouse cucumbers that haven't been pruned at all up to this point. I thought it would be kind of instructive to show off to folks who haven't done any greenhouse cucumber growing before and are sort of interested in it.

This isn't what I would say a worst case scenario because you can definitely come back in here and clean the plants up and they'll be fine. But it's going to be a lot of work and it's a pretty big mess. So you can see that the side shoots are already starting to grow so long that they're coming out onto the floor. They're starting to put their own fruit out. The tendrils are wrapping multiple plants together. They're grabbing fruit. Basically, you just have a big tangled mass of plant. And in addition to just being harder to harvest and kind of difficult to work in and around, it's also much more likely that you're going to lose marketable fruit. You're going to increase the possibility of diseases like powdery mildew setting in. This is why we prune or in the case of the new variety that we're adding, what we will hopefully be able to avoid happening even if you aren't pruning.

Here we are back again in the cucumber greenhouse trial. It's been about 2 1/2–3 weeks since the last time we were in here and we've fully transitioned into harvest mode for these varieties. We're not in a place where they're still predominantly vegetative. We're harvesting a lot of fruit off of these plants. And so this is the point where we're really starting to see the transition in the plant habit between our two varieties. Looking at our reduced prune variety, you can see at each node, we still have the fruit, we still have a tendril, we still have a leaf, but the actual sucker here is very reduced. It looks a little bit more like almost immature flowers. It's just this little fuzzy lump here, and it's never going to fully grow out into a vine like a normal variety would. Here on this other plant, we can see that same thing happening and basically going all the way up.

As we continue to lower and lean these plants over the rest of our harvest season, we're really going to be able to take advantage of the fact that we don't have to be constantly in here suckering all of the vines. Comparing that to our control, which doesn't have that reduced suckering trait, here after a week without any pruning, we have this sucker starting to really get away from us. And then just going up the plant, we see suckers all the way up.

There's nothing wrong with this plant habit, but as I'm sure many people are familiar with at this point, it's a lot of work to come in here and to constantly prune off these little suckers. And inevitably you miss one and it's halfway across the greenhouse before you find it. And it reduces the vigor of the vine that you're trying to actually cultivate. It tangles up the trellising. There're a lot of reasons why you don't want sort of a big mess in your carefully curated cucumber greenhouse.

Here we are back in the cucumber greenhouse about two weeks after the last clip that you just watched and we're here to show how the plants are continuing to abort the suckers rather than have them develop as you're probably used to. You have at each one of these nodes, you still have the tendril you still have the leaf and the fruit but the sucker just sort of dead ends into this little cluster of small flowers. The flowers themselves never really develop into fruit or anything they just kind of sit there and eventually self prune. And you can see that this starts lower down the plant, continues on its way all the way up and as a grower that means you get to spend a lot less time in here pruning and a lot more time harvesting.

Again, here just as a point of contrast is our control variety that has the more standard suckering plant habit. And you can see after 2 more weeks of no pruning that has some pretty significant suckers. The plants are getting pretty tangled up with each other. And looking up the plant, you have the tendril the leaf the fruit and then the traditional sucker and that's just going to develop in the way that it usually does, meaning that you do have to spend time and energy pruning it off.

Because nothing in life is ever perfect, this cucumber variety 'Demeter' also isn't. We have a situation here that I just wanted to illustrate because we want to make sure that the people growing this variety really understand as much about it as they can and all of the bumps and bruises that come along with that. We have a plant here that has at some nodes self pruning suckers that have these tiny little flowerlets developing here that are just going to self prune and abort and never turn into anything, but it also still has regular suckers as well and those will have to be pruned. You can see here's one that wasn't pruned properly probably about two weeks ago, and we're at about four nodes down at this point.

We do feel very confident that this variety provides genuine advantages and labor-savings compared to a traditional greenhouse cucumber, but we do just want to be upfront about the fact that it isn't perfect and there will be the occasional sucker even after the plants start fruiting that will have to get pruned off.

We hope this video has been helpful and informative. We're excited about Demeter, and we think it will be a good addition to your greenhouse cucumber program.

Learn more and shop 'Demeter'
Learn more about growing 'Demeter' in our Low-Prune Greenhouse Cucumber Production Tech Sheet (PDF)

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