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Kousha Navidar: You are listening to All Of It on WNYC. I'm Kousha Navidar. Chances are you've thought about your plants recently. I know it's a topic in my household. As the weather gets warmer, we prepare our plants and gardens to thrive. Chris Satch, also known as The Plant Doctor is a regular guest, friend of the show, and he gives us advice on how best to care for our plants depending on the season.

Chris recently spoke to guest host Matt Katz about preparing our plants for a healthy spring bloom. We took your calls and questions in this segment, but today is an encore presentation. Even though you'll hear callers throughout the conversation, we unfortunately can't take your calls live right now. Here's how the conversation started. You know that it can be hot one day and cold another during spring. Matt asked Chris what these temperature fluctuations can mean for our plants.

Chris Satch: They actually know a lot more about what's going on than we do. It also depends on the plant, and it depends on whether you're growing indoors or outdoors. For your indoor plants, you're going to start to see some new growth coming up soon as the days get longer. If you aren't seeing some growth now, you should be.

Then there's outdoors. Outdoors, the witch hazel, those trees are all in full bloom. Usually, the first ones to come out are witch hazel, skunk cabbage, and crocuses, but then you'll have your other spring ephemerals and bulbs come up as the months go on. Also indoors, you're going to want to start to plant some of your seedlings for transplantation into your gardens later.

Matt Katz: How do these plants know that spring is upon us? It's not like there's been weeks of warmer weather. What is going on inside of them to know this? How does that work?

Chris Satch: Yes, so much like we humans have a circadian rhythm, plants also have a circadian rhythm. Even though the trees outside may look like they are not leafy, they may look like they're barren, they may look quite like they're dead, but they're actually quite alive. If you look really closely at most of the trees, you'll notice that the buds are usually a nice fresh red color, pinkish color, bright brown colors. What they do is they still photo-sense light. They can sense the light and they can time the cycles of the day to line up to when they should come out.

Now, they don't just take light as a cue. They also take the warming temperatures as a cue as well. You'll see some very-- and some trees do get confused by odd weather patterns. For example, in the middle of January in some sort of shaded maybe north-facing courtyards, you might have a cherry blossom tree that randomly is making flowers even through the dead of winter.

That plant got the wrong cues because in certain places it can be more mild than others. With buildings, they create microclimates in between the buildings and among the buildings and around courtyards and things like that. How close you are to the water also affects how mild the temperature will be. Speaking of bodies of water, the Hudson River and the Atlantic Ocean, and the Long Island Sound actually modulate our climate such that New York City is in a much warmer planting zone than is upstate or even as you start to get north of Westchester County. They're in an entirely different planting zone. We're like a warm seven to a cold eight zone whereas the rest of upstate is seven to six, all the way up to five if you go north enough.

Matt Katz: Got it. What about climate change and how plants here might be feeling that, or noticing that, or adjusting to it?

Chris Satch: Oh, yes, they're definitely noticing it. Climate change is happening at quite a fast rate. We're still observing how they're doing things, and I've noticed from my own personal observations. I love watching the cherry blossom trees. I've seen in the past 5, 10 years, them popping their buds too early for a lack of a better term, coming out, and then we get sort of like a fake out spring here in New York, and then we get some random cold snap at the end of March or at the end of April.

When they get wiped out like that, their entire crop or most of their crop gets wiped out. That doesn't just have effect on the plants. That also has effect on upstate farms. If we get a late season frost or a surprise frost because the climate is unstable, because it's changing, because the climate doesn't know what to do, that does affect food prices and that does affect apple yields, apple picking, all the other things that we like to do when we all go upstate. [chuckles]

Matt Katz: Let's go to the phone lines. Got a bunch of questions already coming in. Adam in Pelham, I think, wants to ask about daisies. Hi there, Adam.

Adam: Hi. I'm Adam. I'm from Pelham, New York, and I got a quick question. I have some daisies seeds and some plastic containers, those little ones that are about an inch and a half in diameter, and I wanted to fill them with soil and then put the seeds in them and germinate them. What's the best way for me to do that?

Chris Satch: Daisies are pretty easy. You can start them now-ish. I think this is the end of when you would start your seeds indoors. Daisies, you can start a little later. You might want to wait a week or two on them, and then you could sow them. I guess, I think what you're describing is a seed starting tray, like a big black plastic tray with the compartments in them, and you just fill the compartments with just regular potting soil.

Depending on the type of daisy, you'll plant them at different depths. Most of them actually don't get planted very deeply. Maybe it's a quarter inch. Just follow the instructions on the seed packet and make sure you pack the soil tight. I know one way that folks who are starting seeds might go wrong, is when you get the bag of soil and you first plant things, it's very loose. You want to compact it and you want to make sure that you water it right after you plant it with warm water to help with germination.

You want to make sure also that the seed tray is in a warm area, that it's not getting a cold draft. I know a lot of people use what's called heat mats, plant heat mats, basically like an iguana heat mat. It's a black rubber mat with electric lines going through it, and it heats up through the electricity and it keeps the seeds warm. You'll set that by your window so that way they get as much direct light as possible. Some people try to start seeds under lights. That's fine too. I know that certain plants like chamomile specifically, I can't think of the other ones off the top of my head, but there's a few plants you got to watch out for, that need some light in order to germinate.

Seeds like chamomile seeds or very, very thin poppy seeds as well, very, very tiny seeds, they generally, you don't plant them at all. You actually just scatter them across the top of the soil and they take the light as a signal to germinate. That's how they germinate. It's okay if they splash around a little bit. That's why they have so many of those tiny seeds because the plant knows that not every seed is going to make it. [laughs]

Matt Katz: Right. Thanks for calling, Adam. Chris, in general, is now the right time to start seeding?

Chris Satch: I would first start with longer-term plants or plants that take a while to get established, like your tomatoes, your bell peppers. If you're trying to grow watermelon, cantaloupes, cucumbers, things like that. I would start maybe the tomatoes, and peppers, and eggplants first, then maybe half a week to a week later, then you can start your watermelons and cucumbers and things like that. Then, you can move on to your herbs. Your herbs, you want to start more late.

Of course, you want to be careful because not every plant is transplantable. There are some plants that you may want to start them indoors, but it really is just best to either directly sow them in the ground outside or just plant a piece of them in the fall of the previous year. These are like root vegetables or bulbs or things like that. Garlic, you want to plant last autumn. Tulips, you want to plant last autumn. You can still plant them in the springtime. They just won't be as robust as if you had planted them in the autumn, but now is a great time.

Matt Katz: I think you just answered a question that another caller had, Erin on the Upper West Side. She was wondering if it's too late to plant bulbs and if she can plant bulbs that are two years old right now.

Chris Satch: If the bulbs are starting to poke some green out, if like-- You know how when you buy garlic at the store or you buy an onion at the store, and if you let the onion hang around for too long, you start to see it turning green and wanting to grow? If it's already doing that, then just plant it outside. That plant is already ready to be planted outside. Again, it'll take a hit from not being able to have been vernalized, but because it's already sprouted, it's been vernalized, so it's ready to pop up in the spring.

Matt Katz: We got a question via text message, "Help, I left my gardenia outside. It's brown but alive."

Chris Satch: I don't know what brown but alive means. Brown usually means dead.

[laughter]

Matt Katz: You are the plant doctor so, yes, you should know that.

Chris Satch: There can be some cold damage that can appear brown. I know that for most plants across the board, if it's got some frostbite on it, the leaves will go limp. They'll turn this watercolory purpley gray brown as if you mixed purple, gray, and brown altogether and made it watercolor. That's what the leaves will start to look like. Then, they'll be limp and you just cut them off. There's no way that the plant can recover that. The only way that the plant can recover is if you make conditions nice enough so that the plant can grow new leaves.

Depending on the severity, sometimes you can revive it. If there's some green somewhere else around the plant, or if there's a bud somewhere else around the plant that's green or has the colors of life in it, then it's possible to bring it back. But gardenias, if it's like the houseplant gardenia type that you get at grocery stores and hardware stores, that one's not as frost tolerant. I would keep it indoors, and if it doesn't do anything for a month in a sunny window, then it's dead-dead.

Matt Katz: All right. Good to know. You said cut it off. Talk to me about pruning for a minute. How can you tell when something needs to be pruned in order to revive a plan or just to keep it healthy?

Chris Satch: Yes. I actually had this conversation with a client for NYC Plant Health this morning. We were talking about repotting versus pruning, because when you have indoor plants and they start to get too big, which is by the way, a great problem to have if your plants are getting too big. You have the option of either repotting the plant so that it can continue to grow larger, or you have the option of pruning it back so that you don't have to repot it.

When you're looking to prune a plant, just make sure that, number one, it's grown larger since you've gotten it. Number two, it's not growing in some kind of weird or awkward way. A lot of times, we use pruning to tame plants or to try to make them grow in a way that we want. In fact, the very, very OCD version of that is the art of bonsai, where you really want to control the way that the plant is growing. You do that by pruning them, but only certain plants can have the stuff to be bonsai. Only certain plants can be bonsai.

Matt Katz: I was just wondering, when you do the repotting, how do you make sure it's going smoothly and it doesn't traumatize the plants?

Chris Satch: Good question. When you repot, I like to let the plant go a little dry before I repot, because if you're working with wet soil, it just gets really, really messy, especially indoors. I like to let the plant go a little dry. It makes it easier to pull out of the previous pot. Some plants, if they haven't been repotted in over a couple of years, it's probably time to repot those plants. You definitely want to-- The general rule is whenever the media goes bad, and you can tell by the color of the medium. You know when you first plant something, it's like a blackish brown, and then it starts to decompose over time, because most potting soil is made out of peat, and it decomposes over time.

When it starts to become finer, and muddier, and blacker, and it starts to have a weird smell, it's definitely time to repot. In fact, that might be over time to repot. As a general rule, when you first get a plant from the store, the idea is that the store sells it overgrown. The idea is that within the first two weeks of you getting that plant, you're supposed to repot it. Then after that, it's maybe once a year, once every two years, or if you want to keep it in the same soil, keep it going until the soil starts to get sour.

Matt Katz: We're going to go to one more caller before I let you go, Plant Doctor. Dee from Yonkers, you're on the air. Hi there, Dee.

Dee: Hi. I'm trying to find out about the step after we’ve planted the seed. We get the seedlings, and you see all those beautiful seedlings on those catalogs that look nice and bushy. Then, of course, yours start coming up leggy and might not have the best exact environment, plus the transitions to outside. What are the tips that you can give us to have the most robust seedlings that we can so that we can have the best crops that we can get?

Chris Satch: That's a really good question. This answer is both long and short, so bear with me. First, the seedlings being leggy. Legginess are when a plant is stretching itself too much is a sign that you're not getting enough light. Where most people go wrong with both seedlings and indoor plants in general is they just do not understand how much light that plants need. Another way that I describe it is that plants are living solar panels. There's no such thing as a low-light plant. I know they're often sold like that. It doesn't exist. It just doesn't make sense because a plant is a solar panel. There's no calories in water. There's no calories in soil. There's no calories in air. The only way that it can get its calories in order to grow leaves and do things is through the sun.

In order to make your seedlings as bushy as possible, you want to blast them with as much direct sun as you possibly can. That's either a south-facing window that's unobstructed, or what I like to do is take a south-facing window that's unobstructed and add plant lights to it. Really, really blast those seedlings with plant lights. If you're unfortunate enough to not have a wonderful south-facing window where you can blast them with light, then you can get any of the grow lights that they have.

Usually, for a bulb, and I'm not going to get too deeply into this, but you want either some kind of really good photography bulb that mimics natural sunlight. Those are really, really good. There's also some of the grow plates from some of the cannabis growers that are on the market right now that are fantastic. They have grow tents as well that double for cannabis as well as starting vegetables. You might want to check into that.

Now, the second part of your question is what do I do with the seedlings once they start? Keep them watered. Just note that in their tiny little seed starter cells, they will be cramped after a while. They'll eventually start to need more water more frequently and they'll start to get taller. There comes a point where maybe they're about four or five inches tall, especially if they're in those little one-inch, one-and-a-half-inch cubes or two-inch cubes that you'll almost need to water them every single day. That's about the time when you should be transplanting them.

If it's still too cold outside, you'll just have to transplant them into larger pots and wait until the weather becomes more favorable after our last frost date for the ones that are not cold hardy. If the plants you're growing, like maybe it's kale, maybe it's spinach or something, spinach is better as directly sown seeds outside anyway, but if you do decide to transplant it, you can get away with about a week or two before the frost date. As long as it's not a hard frost like in the 20s. It can tolerate a light frost.

Kousha Navidar: That was Plant Doctor Chris Satch speaking with All Of It guest host Matt Katz about how best to prepare our gardens for the springtime. That's All Of It for today. All Of It is produced by Andrea Duncan-Mao, Kate Hinds, Jordan Lauf, Simon Close, Zach Gottehrer-Cohen, L. Malik Anderson, Luke Green, and Aki Camargo. Megan Ryan is the head of Live Radio. Our engineers are Juliana Fonda and Jason Isaac. Luscious Jackson does our music. I'm Kousha Navidar. I appreciate you listening. I appreciate you and I will meet you back here next time.

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