GB 334 Q&A Rhubarb for Hot Climates? Lights for Seedlings?

The first question on the Tuesday Q&A edition of the Garden Basics podcast is about growing rhubarb in hot weather. Fred and his guests, Master Gardeners Kathy Morrison and Ruth Ostroff, discuss their experiences with growing rhubarb in Sacramento. They also share a rhubarb recipe.
The second question is about grow lights for starting tomato and pepper seeds indoors. Fred  and Debbie Flower explain the importance of using wide-spectrum light systems and mixing different types of bulbs. Debbie also emphasizes the need for air circulation and movement for young plants. Fred and Debbie discuss different options available in the market for lighting systems for seedlings.

Previous episodes, show notes, links, product information, and transcripts at the home site for Garden Basics with Farmer Fred, GardenBasics.net. Transcripts and episode chapters also available at Buzzsprout.

Pictured: Rhubarb stalks

Links:
Subscribe to the Beyond the Garden Basics Newsletter https://gardenbasics.substack.com
Smart Pots https://smartpots.com/fred/
Dave Wilson Nursery https://www.davewilson.com/home-garden/

LED and Flouorescent Light Systems for Seedlings 

How to Start Rhubarb Seeds (Texas A&M)
Source for Rhubarb seeds (in Australia!):
http://www.frenchharvest.com.au/index.php?main_page=product_info&products_id=11

Upside Down Rhubarb Cake recipe(from Master Gardener Kathy Morrison, the Sacramento Digs Gardening newsletter)

Fair Oaks Horticulture Center

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Chapters

• 0:24 Q&A Grow Rhubarb in a Hot Climate?
• 8:03 Q&A Grow Lights for Seedlings?
• 19:46 Got a Garden Question?

Transcript

334 TRANSCRIPT Q&A Rhubarb, Lights for Seedlings 

Farmer Fred

Welcome back to the Tuesday edition of the Garden Basics with Farmer Fred podcast. Unlike the Friday edition, we're dedicating the Tuesday podcast to answering your garden questions. Stay tuned to find out how you can get your garden question into the program. So come on, let's do this. 

Q&A CAN YOU GROW RHUBARB IN A HOT CLIMATE?

Farmer Fred

We like to answer your garden questions here on the Garden Basics podcast. I had one from my eye doctor last week. in between her saying, “Okay, which is clearer, the first one or the second one?” She said, “Can you grow rhubarb here?” 

Whoa, nobody's ever asked me that in all the years, the decades, that I've been answering garden questions, nobody's asked me about rhubarb. And she said, well, I remember fondly having it in the family yard back in Indiana. And I started doing some inquiries and it turns out everybody fondly remembers it from the Midwest. Well, there's a clue for you. 

And sure enough, rhubarb generally does not like to be grown in hot weather. It just doesn't do well here. If you live along the coast, fine. But if you live in a very hot area, rhubarb might be left for purchasing at a farmer's market. But maybe, just maybe, there's a variety out there that might work in a warm area of USDA Zone 9.

We're talking with Kathy Morrison of the Sacramento Digs Gardening blog where they have recipes every Sunday, and you can subscribe to Sacramento Digs Gardening, it's free. Ruth, I'm gonna mention your name. Ruth Ostroff is here, Master Gardener too. And Kathy, you have a rhubarb recipe and where did you get the rhubarb? 

Kathy Morrison

Well, the rhubarb came from the grocery store.

Farmer Fred

Sacrilegious! 

Kathy Morrison

Sacrilegious, I know, but I do like to look for it and it was really pretty. It was large and red.  I have a small, small rhubarb plant of my own. It's a “Victoria” variety and it sits under a tree in a very large pot and I keep it very wet. And it's managed to stay alive because of that. But I don't anticipate any harvest out of it anytime soon. 

Farmer Fred

That's the story I hear from a lot of people who have tried it here that, yeah, it kind of grows a little bit, but it then peters out. But Ruth Ostroff over here has been harvesting rhubarb here in the hot Sacramento area and the name of that variety is…?

Ruth Ostroff

Success. And believe me, Success is the right word for it, right name. So Kathy and I both have been growing Victoria rhubarb and I'm having the same thing. I have mine in a pot, it's in the shade, I give it a lot of water, it's kind of small. I live in Rio Linda and it just doesn't seem to like the heat. But a couple of years ago, I was doing some research and I found a website in Australia where they sell extra red rhubarb, it's called Success, and they have the seeds. So I ordered the seeds, and about a year and a half ago, almost two years ago, I started some of those seeds, and I actually ended up with a plant. So it grew. And the first fall I harvested some rhubarb from it and I was pleasantly surprised to see that it's not just red, but it's candy apple red. It is really red. It makes Victoria look green. This rhubarb, I've made pies out of it and compotes and I like to make rhubarb lemonade. The problem with it, it's not really a problem. In fact, a lot of people might think it's a plus. This rhubarb is not as tart as the standard rhubarb.

My mother was from the Midwest. She was from Iowa and they grew rhubarb. So we always had rhubarb when I was growing up and it was very very tart and I loved it. We had pies all the time. This Success rhubarb, when I made the pies, I've had to add a little lemon juice because it's just not quite as tart but it's super sweet.  I like to just chew on it. It's, well I'm a little different that way. I like to suck on lemons too. 

Farmer Fred

And you mentioned earlier that you're growing it in full sun.

Ruth Ostroff

I am. It's at the end of one of my vegetable boxes because I wasn't sure what to do with it. I wanted some nice rich soil for it and I put it in this box. It gets full sun, Sacramento sun. 

Farmer Fred

Sounds like it needs good drainage too. 

Ruth Ostroff

I think it does.  It does get very good drainage and I fertilize it, but I don't give it a lot of extra care, and it's huge right now. 

Farmer Fred

Well yeah you had your hand stretched out earlier that it was probably what, three feet round? 

Ruth Ostroff

Three to four. Three and a half maybe. 

Farmer Fred

And that's growing for a year?

Ruth Ostroff

Yeah, year and a half. 

Farmer Fred

Wow. And you're already harvesting it. 

Ruth Ostroff

Several times. I made pie for several holidays this past year. And I've made some other things too. Like I said, compote and various things. 

Farmer Fred

How do you start the seeds? Stick them in the ground, right? 

Ruth Ostroff

No, I did them in pots. I did them in pots in my garage. That's a really good question, Fred. I might have to get back to you on that. 

Farmer Fred

OK. I can find it on the Internet, I'm sure (excellent rhubarb seed starting instructions at the link in the show notes to Texas A&M University). Now, when you found this website in Australia that offered this Success rhubarb, did it say it was bolt resistant?

Ruth Ostroff

It actually has flowered. It has sent up a flower stock. Just like a regular rhubarb does. I've found that with my other rhubarb. I just cut them off and it doesn't seem to affect it; it keeps on plugging along. 

Farmer Fred

And how do you harvest rhubarb? Do you cut it or pull it? 

Ruth Ostroff

I pull it off the bottom, get the whole petiole. That whole red part is the...petiole and the leaf is at the top, so it's the stalk of the leaf. It’s just one big long leaf and you can cut it. But I found, like with chard, I'll cut my chard also but it's really better when pulled. It tends to rot sometimes, the little stemlets that are still stuck on the ground I like to pull them off too, so I harvest it like that. And the edible part is the red long petiole. It looks like a stem. What people might think is a stem, it's actually that long, skinny part of, and I don't eat the leaves. The leaves are  very toxic. All of it has some of the same chemicals, but the leaves are excessive. 

Farmer Fred

Yeah, I've heard that about rhubarb is that, yeah, you can eat it like celery and eat the stalk, but don't eat the leaves. 

Ruth Ostroff

Don't eat the leaves. 

Farmer Fred

All right. Well, that's good. Success rhubarb. And in Sacramento Digs Gardening, Kathy Morrison, you have a recipe for… is it a rhubarb cake?

Kathy Morrison

It's a rhubarb upside down cake and you can use just rhubarb. I used the recipe as printed. I used rhubarb and blueberries in stripes. Striped stalks of rhubarb and then blueberries in between. But you could use anything that's fresh right now. Raspberries would be wonderful also. Yeah, and it's a little upside down cake. So you don't have to worry about the rhubarb sinking into the cake. It's already, it's flipped. Because I do a lot of reading of recipes before I start something and everybody said well the rhubarb sinks into the cake when you try to put it on top so put on the bottom, and flip it over. It's a great little cake. It would work for brunch.  My husband who does not like rhubarb generally  just devoured it. So yeah. Yeah, you know it. 

Farmer Fred

We're in the standing in the herb section here at the Fair Oaks Horticulture Center on an Open Garden Day, on a Saturday in May. And we're downwind from the lemon verbena and it's just wonderful. But that's a good tip. So you got the recipe for the upside down cake already up on Sacramento Digs Gardening. 

Kathy Morrison

It was a couple of weeks ago.  I could tell you the date. It was published on April 28th. 

Farmer Fred

Well, that's a familiar date.

Ruth Ostroff

That's Fred's birthday. 

Farmer Fred

Yes, it is. It's also official tomato planting day here, as I like to think of it. 

Ruth Ostroff

Yes. And it's Fred's birthday.

Farmer Fred

All right. Well, we're going to start growing rhubarb here now. It's the Success rhubarb. We'll find the seed, but it's worth a try because as gardeners, we love to try something new and that would be new for us. And you've had success with it. 

Ruth Ostroff

I've had success with it, Fred. 

Farmer Fred

All right, Ruth Ostroff, Kathy Morrison. Thanks for rhubarbing us. 

Kathy and Ruth

You're welcome, Fred. Thank you.

Q&A - LIGHTING SYSTEMS FOR SEEDLINGS?

Farmer Fred

We get a garden question from Sydney who lives in zone 7A if that matters. It does Sydney, it does. Thank you for including that information. And Sydney writes, “Thank you for all the wealth of information you provide in your podcast. I've learned so much about gardening over the past year simply by listening to you. I had a question about grow lights and wanted your recommendation on which one I should buy. My intent is to use these to grow tomatoes and peppers indoors and then transplant them later, when the weather warms up. I'm in zone 7A if that matters.” It does Sydney, it does. “Thanks in advance”. For those of you that don't know about zone 7A, what is their temperature low? Basically down to zero. Zero to five for 7A, five to 10 degrees above zero for 7B. So  it gets cold in the wintertime. So you would not be starting seeds outdoors or putting tomato or pepper plants outdoors in early spring in USDA zone 7A and 7B. Mother's Day would be planting time there. I think Debbie Flower would agree with that. 

Debbie Flower

Yes, sir. 

Farmer Fred

Thank you for agreeing with that. America's favorite retired college horticultural professor is with us, helping us to answer questions. And yeah, I guess the key to me in my mind, you want lights that are gonna cover the whole plant. I've seen some narrow systems where it only looks like it covers a few inches wide. And yes, I know light kind of goes out at an angle.

But obviously some parts of that plant are gonna get more light than others. You want more even light. So I think as wide a system as possible. 

Debbie Flower

Yeah, I like the standard four bulb, four foot long fluorescent shop light fixture. 

Farmer Fred

You mean two bulb, don't you?

Debbie Flower

 I like the four bulb. 

Farmer Fred

Four bulb? Okay, that's wide. 

Debbie Flower

That's wide. Yeah, that's 18 inches or so. You can run it on two bulbs, but yeah, four bulbs. 

Farmer Fred

Do you mix the bulbs?

Debbie Flower

I do. 

Farmer Fred

OK, because there's your standard white shop light and then what are called grow lights would have sort of a bluish purplish tinge.

Debbie Flower

Yeah, there's even some regular fluorescent tubes that have a bluish tinge to them. And blue is very important part of the spectrum for plants to grow. It is needed for root and green part development, whereas the pinker part of the light spectrum is for flower and fruit development. To start seeds, you don't need the whole spectrum. If you were gonna grow these plants indoors, produce flower and fruit, then you need the whole spectrum. But to just get the seeds to germinate, you don't need light in most cases at all, certainly not for peppers and tomatoes. But once they're up above ground, you need light, but you don't need the entire visible spectrum. You just need the blue light. The blue in particular, yes. That's the one you'll have to seek out a little more.

Farmer Fred

That's so weird. It's like blue light is sort of the nitrogen for a plant's success and the red color is sort of the phosphorus and potassium for a plant's success. 

Debbie Flower

I guess you could look at it that way, yes. Okay, I don't know why. So  if you went into a shop, they'd probably want to sell you an expensive system that has full spectrum. The plants will grow great. It's not needed just to start plants from seed and grow them to transplant size. Yeah, you're just doing this indoors to get the plants started and once they get up, then you will slowly habituate them to the outdoor world for a few hours in the shade for a few days and then build up the sunlight and also to more of the elements like the wind. 

Farmer Fred

However, I bet you would even say that in an indoor situation on a young plant you would want some moving air. 

Debbie Flower

You've heard me say that before. 

Farmer Fred

Yes, I have. 

Debbie Flower

Yes, it's very critical that you get the stems of the plants to move 10 minutes a day. They need to shake. So if you're starting plants indoors, it's not really windy indoors. It's not even really windy in a greenhouse unless you introduce a fan. And that's where I start my seeds is in a greenhouse, a little tiny greenhouse with a fan that is on a timer to run for a half hour. It's an oscillating fan. So it moves back and forth because I want every plant in there to shake for at least 10 minutes a day, and that strengthens the stem. If you think about it in human terms, if you've ever broken a limb and been put in a cast for six weeks, when you take that limb out of the cast, your muscle tone is gone. It's because you've been unable to move it. A plant is the same way. If you can't move it, it can't create the equivalent of plant muscle tone, which is called reaction tissue. So when it's pushed one direction, it creates some reaction tissue to make it stand up straight again. And it's pushed the other way, and it,

creates reaction tissues that stand up straight. You'll get much thicker, stronger stems out of a plant that moves 10 minutes a day. 

Farmer Fred

All right, so wind, a very important part of this, not just light as well. Yeah, definitely the fluorescent lights, we like fluorescents and you can adjust them fairly easily if you can put them on chains and raise them and lower them. Because with the fluorescent lights, how far away did you keep those four lights, which is a lot of light away from the tops of the plants as they grew? 

Debbie Flower

Well, I'd get them as close as I possibly could. The beauty of fluorescents - my choices back then when I first started this were fluorescents and incandescents, and then halogens came along. Both incandescents and halogens produce a lot of heat, enough to burn a plant when it's very close to the plant. So, I didn't use those. I used the fluorescent tubes which produce light but are cool, there isn't a lot of heat emanating from them. So you can get them close to the plant. But I would keep them at least within two inches of the top of the plant. But florescents run cool. 

Farmer Fred

You wouldn't do that with an incandescent. 

Debbie Flower

Correct. That's why I didn't use incandescents.  And so as things are growing, some plants, I may be starting straw flowers and tomatoes at the same time. Well, tomatoes are an upright plant at the seedling stage, an upright plant. And they will get taller, faster, than the strawflowers. And so I need that light close to both the strawflowers and the tomatoes. So I had eye bolts put in the beams of the ceiling. I hung chains from them. And then I put my fluorescent fixture on the chains. But I could move one end of the fluorescent light up and down independent of the other side. So my light would be at an angle. I'd put the short plants on one side where the light was lower and I'd put the tall plants on the other side where the light was higher. 

Farmer Fred

If you do an internet search for grow lights for seedlings, you'll see all sorts of different systems to do that. And some of the ones in the 21st century, you don't need chains. You can just like loosen it up and slide the bar down a little bit to have that angle if you wanted the angle. And that makes perfect sense to do that, to have the shorter plants on one side, taller plants on the other if you're able to angle it. The other one that intrigues me here is a stand that looks to have four shelves and the four shelves seem to be adjustable. And each of the shelves, five shelves in all,  they each have lights on the bottom of each shelf.  

Debbie Flower

Yeah, I had a structure like that. I had to save and save and save to get it because it cost me a lot of money and  mine only has four shelves. They're very deep, probably 15 inches deep and the shelf height is fixed, but there were bars under each shelf and there you could attach a light to each bar. Okay. But if the shelves were not adjustable, that's of limited use. The lights were adjustable, but, not by much. Just by about two inches. So yes, that's what I like about the free hanging light. You have the most ability to adjust it. You don't have to hang it from the ceiling. You could create a wood or PVC structure if you use the strong enough PVC to hang it from that. I'm looking at one here that really intrigues me. It sells for about $50, producing 6000 lumens of LED light.

And the size of this rectangle of light is about 8 inches long, 12 inches wide, and about a couple of inches thick. But you can get a lot of plants under that light. And you could hang that too and adjust it with those bolts that you put into the ceiling. Yeah, 6 ,000 lumens is a lot of light. Yeah, which has a 600 watt incandescent lamp equivalent. Now what I don't know about these LED, these big LED lights, is how much heat they put out. So that would determine how you would space them above your plants. Yeah, I think LEDs in general are a cool light source. They don't put out a lot of heat. That's one reason they're so efficient. Now, this is interesting too. This grow light is designed with a built in fan and vents in the LED board. The strong cooling system means longer lifespan of the LED. So I guess they do produce heat on their own. 

Farmer Fred

And also better air circulation too, that makes perfect sense. But that does look like an interesting structure to have if you're gonna grow in a rectangle. 

Debbie Flower

Yeah, yeah. And I think you'd still need a fan. I don't think the fan would be strong enough to make the plants move. Another thing to know about fluorescent tubes is that they decline over time. The light gets weaker and weaker, not to our ability to sense it because our pupils regulate how much light we allow in. But to a plant, fluorescent tubes can get very weak. So you don't want to use old used fluorescent tubes. You want to use new ones. I've read things that say you have to change them every two to four years. I think that's if they're under constant use. I just bought one set for my grow light and used it only during seed starting season and I never changed the bulbs. But that's something to know about fluorescents. They decline in their quality and quantity of light they produce declines over time. 

Farmer Fred

One mistake you don't want to make is thinking that a sunny window is enough light to grow seedlings. If you do that, they're going to get scrawny and skinny. And despite your best efforts, even if you turn them a quarter turn every day, they're still going to get skinny and scrawny and not grow straight. So you need that direct light. That's why actually greenhouses are best.

Debbie Flower

Yes. Because you got the full spectrum, which isn't needed for seed germination, but it helps when the plants get bigger. And it's coming from all directions. And don't forget that fan. 

Farmer Fred

Well, again, thanks for writing, Sydney. I hope we helped you out there, and happy growing. It's great to start plants from seed. There's just so many more varieties available in tomatoes and peppers, especially, when it comes to growing some of your favorite vegetables that you can get in seed form as opposed to plant form. So, yeah, keep on seeding away, Sydney. Debbie Flower, thanks for your help on this. 

Debbie Flower

You're welcome, Fred.

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Farmer Fred

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Farmer Fred

Garden Basics with Farmer Fred comes out every Tuesday and Friday. It's brought to you by SmartPots. It's Garden Basics, available wherever podcasts are handed out. For more information about the podcast and transcripts of the podcast, visit our website, gardenbasics .net. And that's where you'll also find out about the free Garden Basics newsletter, Beyond the Garden Basics. And thank you so much for listening.