WHEN GROWING from seed, the listing of choices begins with what seems to be the best query of all: which number of bean or tomato or zinnia to order. However then issues get extra difficult, questions like determining when to start out what, and whether or not any of your decisions want any particular pre-treatment or explicit situations to germinate—together with what germinating medium to make use of.
We’ve all heard the advice to make use of much less peat, the usual for seed beginning till comparatively lately, when this non-renewable useful resource has been underneath scrutiny. However what peat substitutes work and don’t? That’s simply one of many many questions that right this moment’s visitor, Joe Lamp’l solutions on social media and within the “Grasp Seed Beginning” on-line course he affords about his favourite matter, rising from seed, and it’s one we explored collectively.
Joe is host of the favored “Joe Gardener” podcast and creator of a collection of on-line gardening programs. Or maybe him from his former Emmy-winning public tv program, “Rising a Greener World.” Joe gardens within the Atlanta space, and I don’t know every other residence gardener who begins extra seeds every season. He’s additionally the writer of “The Vegetable Gardening Ebook: Your Full Information to Rising an Edible Natural Backyard from Seed to Harvest” (affiliate hyperlink).
Plus: Remark within the field close to the underside of the web page to enter to win a replica of his e-book.
And: For a restricted time, Joe is providing A Solution to Backyard readers entry to his “Grasp Seed Beginning” course at a $100 low cost; be taught extra concerning the course and use the code SEED100 at this hyperlink.
Learn alongside as you take heed to the Feb. 23, 2026 version of my public-radio present and podcast utilizing the participant under. You possibly can subscribe to all future editions on Apple Podcasts (iTunes) or Spotify (and browse my archive of podcasts right here).
finest germination mixes, with joe lamp’l
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Margaret Roach: Hiya there, outdated buddy. How are you?
Joe Lamp’l: I’m good, Margaret; I’m simply fantastic and I’m excited to be speaking to you. Thanks for the chance.
Margaret: You don’t like seeds or something although, proper? And also you don’t begin any, proper?
Joe: [Laughter.] I like seeds a lot. It might be my favourite factor of all associated to gardening.
Margaret: Yeah, and the images you in that greenhouse, I imply, it’s like 4 billion seeds- [laughter].
Joe: 5 billion, however who’s counting?
Margaret: Oh, proper, O.Ok. Yeah. Do you continue to use the basement develop room [below], too, or simply now it’s all within the greenhouse?
Joe: I do. I exploit that for the germination section. So after I’m sowing my seeds, as a result of I’m normally doing that in January and February, and really generally even in December. Like this yr: It’s loopy chilly outdoors, even down right here in Atlanta. So I would like extra of a managed setting, as a result of the greenhouse can get very chilly at night time. It’s extremely popular within the day. So I’ve security with the seed-starting room, and I’ve been doing it for therefore a few years, it’s laborious to interrupt that behavior.
Margaret: So it’s a side of gardening, seed beginning is, that has a number of questions and choices, as I discussed within the introduction, together with rising medium and which one is finest. And there’s so many concerns and extra, in fact in recent times concerning the topic than ever. I think your college students in your course, which is I imagine beginning quickly… What’s the course referred to as?
Joe: “Grasp Seed Beginning.”
Margaret: “Grasp Seed Beginning.” I count on they wish to know what to make use of. I wager that’s a query that comes up.
Joe: Sure. And never solely that, the nuances of it, as a result of I’ve a really curious group of scholars. And I adore it, they usually’re nerdy and geeky, which is even higher. In order that they’re going deep-dive on these questions. However sure, there are numerous right now of yr particularly.
Margaret: And I’ll give details about the course. I used to be at all times taught {that a} seed-starting medium, that it shouldn’t be a potting soil, it ought to be a germinating combine, which meant that it was soilless, and that it was a reasonably fantastic texture, however sure qualities that it had, however particularly that it was not potting soil. There was a distinction between germinating combine and potting soil. So what are your kind of pointers [laughter]? After which let’s go into the “peat or no peat.”
Joe: Sure, certainly, completely. That’s an ideal query to start out off although, as a result of I get that one on occasion. And in contrast to backyard soil—I’m glad you employ that instance—seed media is de facto designed to be low-nutrient, sterile or close to sterile really, and extremely porous, and a correctly designed seed-starting medium that’s engineered by professionals.
It’s actually designed for roughly 4 issues: Aeration is the primary one, moisture retention is the opposite one. Structural stability; you need the roots to have the ability to maintain collectively with out compaction. After which organic neutrality, since you wish to restrict the pathogen stress. And in comparison with backyard soil, that introduces an entire lot of issues into the combination that aren’t or shouldn’t be included in seed-starting combine.
Margaret: So these are a number of the qualities. After which in fact, as I mentioned within the introduction, additionally in recent times, we’ve been made conscious of the environmental points round peat harvesting. It’s a non-renewable useful resource, and plenty of gardeners have sought to cut back their peat utilization. I imply, apparently, in the UK, the federal government set timetables for banning peat in horticultural merchandise, and apart from taking peat merchandise off the backyard cabinets, the backyard heart cabinets on a schedule, it additionally accelerated that impetus; the federal government stress accelerated product analysis and growth about alternate options. So individuals there, gardeners there bought extra merchandise that had been farther alongside within the analysis course of as alternate options instantly, I really feel like we’re nonetheless tinkering.
Joe: Yeah, we’re a good distance from attending to the place the U.Ok. is with their lack of use of peat, which is okay. And I like watching “Gardener’s World,” and there’s not a present that goes by the place they don’t point out peat free compost, nonetheless they are saying compost.
Margaret: Compost.
Joe: Compost, yeah. I nonetheless can’t say it, nor can I say coir, and the way I’ve been announcing it “coir,” however it’s imagined to be at the very least two syllables, coir. I don’t know.
Margaret: I don’t know both.
Joe: So simply give me some grace there. However that appears to be the fallback, and I’d love to speak about that as we progress by this dialog.
Margaret: Yeah. Properly, I don’t know whether or not we wish to begin with what we use. I imply, have you ever completely mentioned, oh, I’m by no means utilizing any peat once more or, I imply, I’m going to admit first in case there’s any shyness about that: I’ve at all times used, it’s from Johnny’s Chosen Seeds, its 512 Combine. It’s a germinating combine. It’s peat-based; it has different components. It has mature compost and perlite and fish meal and seaweed meal. I’m simply used to it. And that’s one of many issues that I feel is de facto essential, is “used to it.” I perceive the way it feels, the way it handles water. Have you learnt what I imply? I do know it [laughter]. It’s like if you’re baking, and when you change components if you’re baking-
Joe: Margaret, I so know what you imply. And I’m in the identical camp as you, and I readily admit I’m making an attempt my finest to maneuver away from peat moss to one thing extra different and sustainable and that has much less environmental impression. So I’m engaged on it, however on the identical time, on the scale that I’m rising seedlings, and plenty of of them are for our seedling sale with my daughter each spring, there’s 3,500 or 4,500 seedlings that we’re rising out, and I by no means have sufficient time. So I’m at all times racing the clock, and I default again to what I’ve been utilizing for years, simply as you mentioned: the consistency, the predictability, the uniformity of what I exploit is Professional-Combine BX, which is a business grade, peat-based seed-starting and propagation combine that has roughly 70 % peat moss in it, after which some perlite and a few wooden fines, perhaps 25 or 30 %. So there’s a great little bit of different amendments into it, however the bulk of it’s peat moss. And there’s coir and there’s Pitt Moss, and there’s not a number of rivals on the market that I’ve discovered but that I’m joyful sufficient with to completely convert to.
Margaret: Proper. And one factor I’ll say is I exploit a lot much less germinating combine (I germinate issues on a a lot smaller scale than you do) than I do say potting combine for my large containers outdoors. With these, I’ve been very rather more aggressive to maneuver towards… Properly, there’s a number of merchandise which have a bark base or a wooden base, so to talk, and have compost in them and issues like that. I discovered that transition lots simpler with my potting mixes than with the seed-starting mixes.
And even a number one professional on this topic, a professor at North Carolina State College, I talked to him a few years in the past, when this was kind of actually all attending to be louder and louder, the problem about peat. Brian Jackson’s his title, and he mainly mentioned, “Go slowly,” though he’s an professional and he’s doing all this analysis and so forth, as is his trade. Go slowly as a result of you possibly can’t simply say, “Oh, I’m going to go from utilizing this for all these years to utilizing one hundred pc coir,” or no matter and essentially have good outcomes.
Joe: Within the potting combine, you have got so many extra choices that you may put into it. Plus you’re placing in established crops that aren’t infants popping out of seeds. And so there’s that hardening-off section the place you simply can’t actually topic your seeds to so many unknowns, and also you’ve bought to have that sterility base and the fantastic texture, and it has to do all these issues so far as retaining moisture and releasing sufficient of it. Then you must take into consideration the pH. And so it limits your choices considerably, which is why we’re again to only a handful of acceptable decisions.
Margaret: Now, you mentioned Pitt Moss earlier than, and folks might have thought mentioned peat moss, however Pitt Moss is a model of other germinating medium that’s produced from recycled paper merchandise?
Joe: Yeah, it’s mainly recycled paper. It’s post-consumer cellulose, cardboard and paper waste that’s been upcycled. It’s been cleaned and pulped and engineered right into a peat different. They usually’ll even let you know that the intention is de facto to not make it one hundred pc replaceable with peat, as a result of they acknowledge it’s bought a special texture, it’s bought a special mechanical cohesion issue that helps it bind collectively if that’s what you’re searching for, and another issues that make it extra of a praise than a alternative. And the complement could also be 30 to 50 % of the whole.
And if you use it that means, and also you get used to the nuances of utilizing it, I feel it does an ideal job of holding moisture; you’ve virtually bought to watch out about it, however when you dial that in, and I’ve finished this, it’s superb. In truth, I recall one yr after I was actually testing it, the very best trays of seeds and seedlings that I had got here out of the Pitt Moss system. And so have I modified totally to make use of 30 % of that in my combine? No, I haven’t, as a result of as I discussed earlier, I get time-crunched after which I’ve to default again to what I do know I don’t have to consider, after which it finally ends up my different combine.
Margaret: Proper. And that’s mainly what Dr. Jackson at North Carolina State mentioned. He mentioned strive utilizing your acquainted factor and step by step including a bit little bit of one thing completely different. So just like the Pitt Moss or no matter. And coir is without doubt one of the components that lots of people have additionally tried doing that with.
Now I’m simply going to sound like an outdated no matter, which I’m [laughter], by the best way, about 127 years outdated, however don’t I sound good for 127? However coir isn’t precisely environmentally groovy in my thoughts, both. It comes from different locations on this planet; it has to get shipped far and wide. It used an amazing quantity of water to scrub the saline, the salt out of it, to desalinate it. And it’s an advanced factor in its personal proper. I imply, if I lived close to a bunch of coconut timber, have you learnt what I imply? That might be one factor, however this can be a complete different. So I’ve my very own points with that, and that’s not the answer I actually need. So I like that you just’re saying that you just’ve been making an attempt the Pitt Moss, and that you just’ve at the very least been ready so as to add a proportion of it with good consequence.
Joe: Sure. And again to the coir, you mentioned it very nicely. I’m nonetheless engaged on it.
Margaret: [Laughter.] Stick to me, child.
Joe: So again to the coconut husk. Can I simply name it that? [Above, coir from a brick, after hyrdating.]
Margaret: Yeah.
Joe: In precept, it may be a superb propagation medium. However right here’s the opposite factor about it, Margaret, you talked about the environmental points with it, they usually do. It has an entire different set of points we’d like to consider in live performance with whether or not or not it’s a great different. However uncooked coir, unprocessed coir usually or normally incorporates residual salts.
Margaret: Sure.
Joe: And potassium and nutrient imbalances are thrown out by it. And that may hinder the germination and the seedling progress. And what occurs on a regular basis, and I do know this over years of getting nursed my college students by this course of after they’re making an attempt to make use of that different of coconut husk, they usually have actually dismal outcomes utilizing it straight.
In order that they go to the House Depot or Lowe’s they usually purchase the coir brick or the bag of it, they usually plant straight into it. They usually like me after I did side-by-side facet comparisons, it’s unbelievable how stunted and stagnant and stalled the seedlings are after they barely germinate. And the side-by-side comparability reveals 4 completely different seed mediums. One was coir and the others, it was the traditional stuff. And I say, “On this image, how outdated do you assume the one on the left is?” which is the coir, in comparison with the opposite ones. And so forth the opposite ones, they’ll say, “Oh, I don’t know. These appear like about 4 to 6 weeks outdated.” And the one on the left, they are saying, “That’s 4 days, 5 days.” [Photos below.]
They had been began on the very same day they usually had been all 5 weeks outdated.
In order that’s the problem. However what occurs is individuals don’t know that it must have a buffering interval. So we hear concerning the salts and so ceaselessly individuals would say, “O.Ok, I simply must get the salt out of it.” And there’s only a few firms that go to the additional hassle and expense to course of or buffer out the chemically sure salts. So there’s one factor the place they develop, you’ve already talked about that, consider Gilligan’s Island-
Margaret: They wash it, proper?
Joe: Yeah, they rinse it. However the chemical binding of the ions and salt, consider the coir fiber as a magnet that’s negatively charged. And the salt ions are very interested in that as a result of opposites entice. In order that they chemically bind to the fiber, and so rinsing doesn’t launch the sure ions. They’re nonetheless adhering.
So in the case of us unprocessed, and we simply hydrate the brick and we plant into it, and we expertise what I simply talked about, they’re pondering, “Properly, what simply occurred?” After which they are saying, “Properly, I’ll repair that. I’ll make a brand new batch and I’ll rinse all of it out.” In order that they put it out in a bucket or a hose or one thing like that. Properly, guess what? That doesn’t do it both, as a result of perhaps you wash off the exterior bits of salt, however the sure items are nonetheless there, the sure ions.
And so you must buffer it. And buffering is a step. It’s very fixable, and we are able to all do it at residence with mainly a tablespoon of Calcium nitrate in a bucket of water soaked in a single day, after which one other rinse. And that may mainly exchange the salt with the Calcium nitrate and provides the media what it wants, and will get rid of what’s hindering the expansion.
However that’s the problem that folks don’t know to do. And nobody actually talks about it; I ought to have been speaking about it prior to now, and I’ve a bit bit. However we have to actually carry that residence as a result of if we’re searching for an alternate and we wish to strive coir, then except you’re shopping for it already processed, and like I mentioned, only a few firms do this, it’s good to do this when you’re anticipating to achieve success. And what makes me mad about it although, is the businesses that don’t course of it, don’t say something about it. After which sadly, the brand new gardeners and the individuals which are making an attempt this for the primary time get very disenchanted with it, and so I don’t need that to be a damaging factor and have them assume that they’ll’t begin seeds, and it wasn’t even their fault they usually didn’t even realize it.
Margaret: And once more, I’m simply going to underscore, and… It comes from midway around the globe, nowhere close to you, used a number of sources the place it was produced and rinsed initially, and many others., after which has to get shipped all around the globe. So it’s a difficult useful resource in itself. Which is why I like the concept of if it may possibly work for 30 % or one thing of my medium to make use of one thing like Pitt Moss, or who is aware of what’s coming subsequent, which is a recycled product of a extra native nature. I form of am loving the concept of that.
Joe: Completely.
Margaret: In order that’s what I’m searching for. If I’m going to alter, I wish to change one thing that performs, in fact, but additionally doesn’t have environmental havoc connected to it [laughter].
Joe: So on that notice, there’s just a few different ones, and I such as you actually just like the Pitt Moss, and I applaud them for making an attempt to give you an answer to not solely upcycle waste that’s destined for the landfill, however put it right into a product the place we are able to develop crops. Nothing fallacious with that.
And once more, they’re probably not pushing it as a one hundred pc alternative, however leaf mould is one other one which we might do. And we’re all acquainted now with go away the leaves. And so I feel twice earlier than I used leaves for something, however I talked to David Mizejewski of the Nationwide Wildlife Federation not too way back, confessing my guilt about utilizing any shredded leaves in my backyard, and he made me really feel a bit bit higher about it. If I’m solely utilizing a bit little bit of the whole, then that’s O.Ok.
However anyway, leaf mould, like with the U.Ok. and Monty Don, he does lot of that in his combine, together with some selfmade compost [laughter; mimics a British accent] and I can’t say it, oh my goodness. However yeah, that’s an possibility. And perhaps some wooden fiber, if you may get bark fines which are finely floor, that might assist with drainage. And it takes up a few of this house that we’re making an attempt to not use as a lot peat moss for.
Margaret: Proper. So one different factor I wish to undoubtedly ask you about is you do a number of soil blocking, not rising in cells solely or flats solely, however soil blocking. And so the opposite factor a couple of medium is that if we’re going to soil block, if that’s our purpose, some mediums don’t… even some conventional peat-based ones don’t maintain collectively in addition to others for blocking, proper? I imply, that’s the opposite factor. It’s a must to kind of do a trial run, I feel, to be sure that the medium you select goes to carry up in blocks.
Joe: You do. Peat moss really has fairly good cohesion.
Margaret: In order that’s going to be, that’s one thing that offers you a bit bit extra of a assure.
Joe: It does, and it’s higher than coir. However what makes something that you just use to make soil blocks, it’s good to have consistency and also you want robust fiber. And if you introduce bulkier materials into it, that breaks up the cohesion and nothing goes to carry collectively nearly as good. So what you’re making an attempt to do is eradicate the cumbersome issues. So reasonably than perlite, you’d use perhaps vermiculite; you would use perlite, however vermiculite is extra compressible and it holds moisture higher and it helps bind the moisture. And so which may be one other dialogue utterly.
Margaret: No, I used to be simply curious if there was any warnings or no matter about that, as a result of I do know I simply noticed you lately did a video about soil blocking, and the way you’re an advocate of it. I feel,
Joe: Yeah, I’m very a lot an advocate as a result of along with making an attempt to cut back my use of peat, I’m making an attempt to cut back my use of plastic, single-use plastic. And it’s nice for house saving and never having to have all these containers stacked up. I attempt to reuse every thing, even when it’s not supposed to be long-term use, I attempt to make it that. However I like the concept of only a clear, low-profile, minimalist potential to develop that many seedlings with out a number of plastic laying round.
Margaret: And I imply, what different issues, if you do the course, what are a number of the different kind of sizzling subjects or those the place you’re feeling like probably the most instructing must be finished the place individuals get into probably the most hassle [laughter]?
Joe: Lighting and watering, completely.
Margaret: Sure.
Joe: Yeah, lighting and watering each time, and watering, it’s humorous, watering, it appears so primary and there’s nothing technical about it, however it appears to trump the lighting questions as a result of persons are fighting the watering extra. And I perceive why. Even with soil blocks, and so long as I’ve been gardening as many professionals as there are associated to soil blocks, they have a tendency to dry out fairly shortly.
They keep a number of moisture, they soak up it shortly, however earlier than it, between a germination warmth mat beneath it and develop lights above it, they’ll dry out quickly. And so it’s good to be on high of that. So when you’re a traveler (fortunately I’m not as a lot anymore) that might be one that might be tough.
However watering, it’s both they’re watering an excessive amount of or they’re not watering sufficient. And I at all times default again to my favourite method to know whether or not you have got the correct amount of water. And that’s for the seed tray that you just’re assessing, when you can simply get a way of what it weighs when it has the medium in it, however it hasn’t been watered but, weigh it or really feel it. Each could be finest. And then you definitely hydrate the medium and sow your seeds or no matter your order is for that. Now you have got discipline capability, since you’ve put ample water into the medium to completely hydrate it, to the purpose that the surplus water by gravity has vacated the cell tray. So now what’s left is sort of a sponge that you just’ve squeezed, however there’s nonetheless loads of water in it. All of the excesses run out. So now what the field-capacity weight is, or the totally saturated weight that also has oxygen within the pore house, which is important.
So now the 2 extremes: the totally saturated, the totally dry. And so now all it’s good to do is form of gauge what does the center half really feel like when it’s proper in between these two, and that’s your candy spot. That’s what you’re actually going for.
So your muscle reminiscence will kick in and allow you to get a way of, though it might look dry on the highest (oftentimes when the develop mild is overhead, it dries out the floor), however that’s to not say that what’s beneath it’s dry. Additionally, that might be completely fantastic. So it’s possible you’ll assume it wants water, and then you definitely give it a great drink, and now you’ve over-watered it. And we’re making an attempt to keep away from that. So by weight, you possibly can actually dial in whether or not or not it’s good to add water or simply go away it alone.
Margaret: Yeah. Properly, that’s true. So watering, however what you had been simply describing is of how I do with my houseplants, I form of decide up one nook of the pot. I’m like, “Oh, it’s nonetheless bought moisture in there. Wait.” Yeah. Yeah. O.Ok. What are you sowing now? Simply fast, what?
Joe: Properly, I’ve already finished my peppers. I began these December twenty seventh, the recent peppers. After which I adopted up with my candy peppers. And so these are finished, and most of them have germinated they usually’re within the greenhouse. Tomorrow I begin the primary of my most likely 3,500 tomato seedlings, beginning with the slicers.
I’ve realized through the years that I’ve been doing this, I would like to attend to sow my cherry tomatoes as a result of they develop a lot quicker. Two weeks earlier than the sale date, which is normally April 1st, I’m them going, “It is advisable to cease rising. You’re too large already.” And so now I’m going to attend two weeks this time for the primary time, I’m going to change my seed-starting schedule by being selective on what I begin forward of that.
Margaret: Properly, Joe Lamp’l, it’s at all times good to speak to you and particularly about your favourite topic. I’m going to provide details about the course, the “Grasp Seed Beginning” course, and thanks for all of the sage recommendation. And we are able to follow say “coir” collectively, O.Ok? We’ll have a separate session for that.
Joe: O.Ok.
(All photographs courtesy of Joe Lamp’l.)
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