(C) Daily Kos This story was originally published by Daily Kos and is unaltered. . . . . . . . . . . Saturday Morning Garden Blogging Vol. 19.8 Seed Starting 101 [1] ['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.', 'Backgroundurl Avatar_Large', 'Nickname', 'Joined', 'Created_At', 'Story Count', 'N_Stories', 'Comment Count', 'N_Comments', 'Popular Tags'] Date: 2023-02-25 Bearded Iris I have to start today’s SMGB off with an apology. This was supposed to be a free weekend for me. My son, daughter-in-law, and two-year-old grandson switched their schedule and are here this weekend. Since this is their first time in the area, we’ll be out all day showing off our favorite local waterfalls, covered bridges, and mountain vistas. As many of you know from my previous posts, cell reception and internet access is almost non-existent once we get away from the house. I will try to check back when I can, but I am probably going to be a poor host during most of the day. If there are seed specific questions in the comments I will reply to those in the comments and will also KOSmail the commenter to make sure they get the answer ….but it may be this evening or even tomorrow. I apologize up-front that seed-starting just isn’t the most photogenic subject. I’ll sprinkle in a few pictures from my previous garden, but there are no sexy shots like the last couple of months have had of Ireland, Costa Rica, Big Glasshouses, Connecticut gardens, etc. I hope as the day goes on, enough of you will post some pictures to overcome this lack. It’s actually a little ironic that I am doing this blog on seed-starting because I probably won’t be starting a lot of seeds AGAIN this year. Right now, the greenhouse is still just a half-finished design on my desk. I also haven’t begun construction of the raised vegetable beds … I have pots of fruit trees sunk in the ground where those beds go, and the potted trees can’t get moved until I finish getting the sod stripped off of the orchard area. If you have looked at our YouTube channel “Making Paradise” (Making Paradise in VA), you know that we are working steadily on the orchard, so those potted trees should get moved soon. With a little luck, the raised vegetable beds should be built by our last frost date of May 1 and I may set up an inside rack somewhere with grow lights, but I suspect we’ll be using transplants bought from a garden center instead of starting most of our own. Water Lily My father used to start tomato seeds in Styrofoam cups and regular garden soil. I started gardening the same way, except I added a step of cooking the soil in the oven for a few hours to kill the “damping-off” viruses. (I don’t recommend cooking dirt because it stinks up the house and makes my wife mad. ) I expanded beyond tomatoes to other vegetables and flowers using soil-less mixes in plastic, multi-cell seed trays. At one point, my seed-starting area took over a corner of the basement with fluorescent lights and electric heating mats. Following the recommended practice, several seeds were sown in each tray cell and the seedlings thinned to one per cell if they all sprouted. But despite my efforts, germination was inconsistent and I would often have empty cells in the seed trays. All that changed for me in the early 90s when I acquired a germination theory book written by a chemistry professor, Dr. Norman Deno, at Penn State University. More importantly for our story, he was an avid gardener who realized that germination should be evaluated with a scientific approach. Dr, Deno theorized that plants evolved mechanisms to inhibit germination until the conditions are right for the seedlings to survive. Without this inhibitory mechanism, seeds would sprout all willy-nilly at the wrong time of year: tender seedlings could desiccate if they started growing just before a dry season; drown if started just before the wet monsoons; freeze if too late in autumn without enough time to develop winter hardiness; etc. Winter squash Blossom Dr. Deno thought that the inhibitory mechanism was probably the result of chemicals inside the seed that keep the germination in the “OFF” position. The chemicals degrade after the seed has experienced the right conditions. Once the chemicals are degraded, there is nothing keeping the germination process from switching to the "On” position. After germination begins, it is just a matter of the seedling having sufficient light, water, and nutrients to survive. Dr. Deno did not isolate and identify the inhibitory chemicals. Instead, he focused on determining the conditions that best degrade the chemicals. Ultimately, he documented the conditions for over 5,000 plant species and self-published books with his findings. PDFs of his books are now available free of charge at the links at the bottom of this blog. Dr. Deno focused on factors such as time and temperature that he could easily replicate in the lab. Since soil properties (pH, moisture retention, etc.) would introduce variability, he eliminated the soil matrix entirely in most of his experiments. Germination was tested without soil using just kitchen paper towels and polyethylene flip-top sandwich bags (“baggies”). This “Baggie Method” is simple and a reliable way to start most seeds. Peruvian Daffodil Baggie Method: I have used Dr. Deno’s baggie method for the past 30 years. Seeds are started in the baggies on paper towels and transferred to seed trays once they germinate. I have grown vegetables, perennials, annuals, and bonsai seed with this method. I use regular kitchen paper towels …the plain white ones with the half-sheet perforations work great. Full-size paper towel sheets with printed designs work just as well. A single sheet (or half-sheet) paper towel is folded in half, rotated a quarter-turn and folded in half again, and so on, until it is about the size of a smartphone. The smartphone size is then folded in half one more time and the name of the plant written on the outside of the paper towel with a laundry maker (“Sharpie”). Then I soak the paper towel in water and squeeze out most of the water…it should be very moist-to-wet but not sopping. The paper towel is opened back to the smartphone size and the seeds sown on one half. In the picture below, the wet paper towel is on a tupperware lid to keep the water off of my desk while I sow the seeds. The other half of the moist paper towel is folded back over the seeds and the packet is put in a polyethylene flip-top sandwich bag (“Baggie”). The baggie is loosely sealed by folding the flap over. Elderberry seeds spread on half of the moist paper towel A couple of baggie packets with sown seeds The baggie is then kept at the conditions optimal for the seeds to germinate. For most vegetables and many flowers, the packets are simply kept in a loose pile on my desk at room temperature (around 70 degrees). For a few veggies that are more tropical in origin such as eggplant, I might keep the packet on top of the refrigerator where it is a few degrees warmer (but not much above 80 degrees). If I am starting cool season vegetables (broccoli, cauliflower) in the summer months, I put the packet near an air conditioning vent for slightly cooler conditions. I start checking the packets after a few days to look for germinated seeds. Tomato seeds usually germinate within 1-5 days, peppers in 3-8 days, melons and squash in 4-7 days, and most annuals in 2-9 days. Older seeds may take longer if they are still viable. Some perennial flowers may take much longer, but I generally find this method is several days faster than listed on the seed packages. For some seeds that have a LONG germination period, you may need to re-wet the paper towels occasionally or transfer the seeds to a new piece if it starts getting moldy. To check for germination, the paper towel is opened to look for the radicle (rootlet) extending from the seed. Sometimes all seeds of a variety will germinate at the same time, but often there will be a few early ones, a flush of most, and then a few stragglers. Once a variety starts germinating, I check that packet at least every day until either all the seeds germinate, I have enough of that variety, or I decide the rest are no longer viable. Radicle just starting to emerge from the seed at tip of knife blade Because this method gives high germination percentages, I often use the Sharpie to divide the paper towel into different zones. This allows me to put several varieties on each paper towel. For instance, if I want four plants of a particular tomato variety, I put six seeds in one zone on the paper towel and use another marked-off area for the next variety. You can also put multiple paper towels with different seeds within the same baggie. Any seed that germinates is transferred to a soil-less mixture in a plastic seed tray…one per cell. Ideally, I catch the seeds when they are just starting to germinate so the root radicle has not grown into the paper towel. At that point, it’s easy to slide the tip of a pocket knife under the seed and transfer it to the plant cell. If the rootlet has grown into the paper towel, it takes a little finagling to tease it out from the paper towel but usually they slip out without breakage. For some larger seeds such as melons, cukes, and squash, the root can grow really fast ...one day there is no sign of germination and the next day there may be an inch-long rootlet with branching. If this occurs and I can’t tease the rootlets out, I simply rip out the piece of paper towel around the roots and plant it in the seed tray. I’ve never noticed any difference in subsequent growth of the plant. For bigger seeds that I can easily handle, I’ll make a divot in the soil-less mix, put the seed in place by hand, and tamp the mix around it with the rootlet facing down and the seed case just above the surface. For smaller seeds, I usually make a small divot in the mix and use the tip of a pocket knife to drop the sprouted seed into the divot and push a little mix over it. Even if the rootlet is facing up, the seedling will right itself and grow properly. For really small seeds, I just tamp down the surface of the mix, balance the sprouted seed on the tip of the pocket knife over it, and use a spray mist of water to wash the seed off the knife onto the surface, and don’t try to cover it. The rootlet will pull the seedling into the soil to the appropriate depth. The seedling trays are bottomed watered and moved to a location where the seedling can grow before transplanting out. Most plants tolerate lower temperature than needed for germination and grow reasonably well as long as they have sufficient light. I made a small greenhouse at my previous house and could start transplants months in advance even with the greenhouse dropping to 40 degrees at night. Until I get a greenhouse built at the new house, I won't be starting many seedlings until its warm enough for them to go outside and I may have to shift the trays into the house on some nights. My former greenhouse...built with drafty recycled windows. It was heated by a small electric heater that struggled to keep it warmer than 40 degrees on cold nights but produced hundreds of seedlings in the spring. A downside of the baggie method is that my seed trays often end up having several different varieties interspersed around the tray. I try to make sure that I put sun-loving plants in separate trays than shade plants because they get different handling. Good labels are essential to figure out what is what when it comes time to planting out the garden. Germination Requires Oxygen: Seeds need both OXYGEN and MOISTURE to germinate. Moist seeds in foil packets, Zip-Lock bags, sealed jars, etc. will not germinate because they have insufficient air. Dr. Deno found that some species have no inhibitory chemical mechanism preventing germination except for the need for air and water. Pepper and squash are examples with no inhibitory mechanism. They do not germinate inside the fruit because the fruit is airtight but will quickly germinate in moist conditions after removal from the fruit. Just after I wrote this section, I found a few germinated seeds inside a butternut I was cutting up for dinner. Inspection of the squash revealed a small hole that penetrated to the seed cavity. Undoubtedly, the hole admitted enough air to allow germination to begin. The flip-top baggies used in this method keep in moisture but are permeable enough to allow oxygen to get to the seeds. The cheaper the baggier, the flimsier the plastic and thus, the better for this method. The heavier plastic used in Zip-Loc and vacuum-seal bags are too thick to allow air to reach the seeds. Daylily Some seeds require Dry Storage to degrade the Inhibitory chemicals: For most of the species that Dr. Deno tested, there appear to be chemicals inside the seed that inhibit germination. For about half of them, the inhibitory chemicals degrade simply by dry storage conditions after a few months. MOST OF OUR COMMON VEGETABLES have this dry storage requirement. This is probably because earlier cultures selected seeds that could be held over to the next growing season. Dr. Deno did not test a lot of vegetable species because weren't exciting to him. They almost all germinate quickly at room temperature once they have been subjected to a few months of dry storage. The downside of dry storage is that the seeds eventually die. The lifespan of the seeds is variable among plants: I have germinated about 10% of tomato seeds older than 15 years, but I have never been able to germinate any cilantro seeds after a year stored in the same conditions. Basil seeds also show an interesting decline in viability: First year basil seeds exude a gel coating around the seed before the radicle appears and have nearly 100% germination; Two and three year old basil seeds exude the gel coat so it seems the seeds are still alive but only 5% germinate; Four year old basil seeds don’t exude the gel and are clearly dead. On the other end of the spectrum, some palm seeds and lotus seeds remain viable for centuries in dry conditions. I have germinated 20-year old lotus seeds (just by soaking in shallow pans of water), but the records are held by lotus and date seeds that were around 1300 years old. Lotus seeds are known for longevity. Incidentally, the baggie method is an excellent way to check the germination percentage. A friend that once worked in a state ag lab told me the method was very similar to the procedures her lab used, except her lab simply tossed the germinated seeds instead of transferring them to grow. A set number seeds (usually 100) is spread on the paper towel, and then the germinated seeds counted to give the germination rate. Using this method, I know that the heirloom okra seeds I’ve been saving for years are down to around 12% germination. I need to get a couple of plants growing this year to produce a new batch of seeds to save. Some seeds require Light to degrade the inhibitory chemicals: Some seeds require Light (or a combination of Light and Dry Storage, or combination of Light and other Methods as discussed below) to break down the inhibitory chemicals. Generally, Light-requiring species tend to have smaller seeds that disperse by the wind. They naturally do not get driven into the ground due to their small mass. Many perennials, annual flowers, and shrubs have this light requirement. "Light” does not mean bright sunshine because the inhibitory chemicals break down in diffuse light …many of the wind-borne seeds are shaded by other plants that provide protection from drying conditions until the seedling establishes itself. Oftentimes, the seed packages will say something like “Do not cover”, “Sprinkle on Surface” etc. I modify the baggie method slightly for seeds that have a light requirement. I used to put the seeds on top of the moist paper towel inside the baggie, but found that too many seeds stuck to the plastic, Now I cut the paper towel so that only one thickness of paper covers the seed. The single thickness of paper towel allows enough light to reach the seeds while allowing me to easily transfer the germinated seeds to the trays. I make sure to keep the packet with the seed side up. I keep the packets near a windows out of direct sunlight. It doesn’t have to be bright light and you do not want to put the packets in a sunny window because the seeds will overheat and die. Dianthus seeds germinated under a single thickness of paper towel. Most of these should have been transferred to the seed trays a day or two earlier. Nine month old Dianthus seedling grown from the seeds pictured above. Conversely, some seeds’ inhibitory chemicals will not degrade if light is present. Generally, these are heavier seed or ones that get buried by animals. Also, some woodland species disperse their seeds before leaf fall so they end up in darkness as the leaves accumulate over them. For some plants, light may not be an actual detriment to germination, but there are usually other processes required to eventually degrade the inhibitory chemicals. Most fruits have inhibitory chemicals: Almost all fruits that envelop seeds have inhibitory chemicals in the flesh of the fruit that prevent the seed from germinating. In Nature, the inhibitory chemicals get stripped off by an animal’s very acidic digestion process. After passing through the animal’s gut, the seed gets deposited away from the parent plant complete with a little fertilizer package to nurture the seedling. Even after the fruit inhibitory chemicals are stripped away, there may be other inhibitory chemicals within the seed coat itself that still need to degrade by other processes before the seed will germinate. I’ve gotten nearly 100% germination of persimmon seeds recovered from bear spoor. In the absence of sifting through animal droppings for viable seeds, mechanically removing traces of the fruit and soaking the seeds in water over 7-10 days (with changes of water every day) usually removes the fruit inhibitory chemicals. A few drops of liquid dish detergent added to the wash water helps. After washing the seeds for several days, I put them in paper towels and baggies and continue with them at the optimal conditions for that plant. Small ramens are good for washing seeds (when not being used for Creme Brulee) Some seeds require Injury to the seed coat in addition to other methods: Seeds that naturally disperse by larger birds such as turkeys and peafowl usually require some type of mechanical abrasion to break the seed's outer coat before moisture can get into the seed. This is because birds have a severe grinding action with small stones in the gizzard. The bird’s digestion tract destroy most of the seeds, but a few remain intact so the plant can spread via the droppings. Generally, this mechanism applies to the hard legumes (baptisia , lathyrus, etc.) and cotton family seeds (okra, hibiscus, etc.). Just mechanically breaking the seed coat is sufficient to start the germination process in some of these seeds. Others may have inhibitory chemicals that must be degraded. A lot of these seeds germinate well after acid treatment; however I no longer keep strong acids around. Usually soaking the seeds for a day or two, then mechanical abrasion, followed by another week soaking in water is my go-to method before putting the seeds in paper towels and baggies. For larger seeds, a triangular file is handy to nick the outer seed coat or you can rub them on sandpaper. Seeds may require prolonged Warm Periods/ Cold Periods/ or Alternating Periods to degrade the Inhibitory chemicals: Seeds native to areas with distinct warm and cold seasons often require several uninterrupted months of warm or cold temperatures to break down the inhibitory chemicals. Some of these species may even require multiple seasons of warm-cold-warm-cold (or cold-warm-cold-etc/) before they can germinate. Tradescantia requires alternating seasons of cold then warm, and sometimes a second cycle of cold/warm but self-sows readily Dr. Deno determined the optimal temperatures to degrade the inhibitory chemicals are 40 degrees and 70 degrees. Lucky for us, these correspond to the common household refrigerator and room temperatures. Usually, the seeds require a couple of months at the temperatures to degrade the inhibitory chemicals. Many species will quickly germinate once the specified periods of warm and/or cold are met so you need to start checking for germination soon after shifting the baggies to the alternate temperatures. The paper towel method is especially useful with seeds requiring long periods to degrade the inhibitory chemicals. Currently, I have three Elderberry species in baggies on my desk undergoing a room temperature warm period; these will soon go into the refrigerator for a couple of months before they (hopefully) germinate this summer…and this was after an initial washing to remove the fruit inhibitory chemicals. Also our kitchen refrigerator contains an unsealed Zip-loc bag contains baggies with 20 other species. Imagine the amount of space and my wife’s displeasure if I were try to do this cold period in plant trays in the refrigerator! Unsealed quart bag kept in the refrigerator with baggies of seeds for their required cold period Other processes to degrade the inhibitory chemicals: Dr. Deno found that some seeds appear to need “gibberellins” from soil fungi to break down the inhibitory chemicals. He identified a lot of species that need the gibberellin. but so far, I have not had to resort to using it. The other course of action if a seed needs gibberellin is to plant it outside and hope your soil has the correct fungi to help it to germinate. Some seeds appear to need daily oscillating temperatures, and are probably better kept outside if your climate is similar to the plant’s native range. And even Dr. Deno had some species native to his property that he could never figure out how to germinate except by letting Nature take its course. Crinum “Candy Stripe” Baggie Method with pelleted seed: Some seed companies provide “Pelleted Seed” because the seeds are extremely tiny. The pellet is usually a clay with a starch binder around the seed to make it easier to handle. Some pellets have a dose of fertilizer to boost the seedling...it does not seem to be anything that degrades the inhibitory chemicals. Pelleted seed are expensive; some companies charge more for ten pelleted seeds than they do for a package of 5000 regular seed. I have used pelleted seed in the baggie method but I do not like them. The clay dissolves in the moist paper towel and then you have to pick out the seed from the debris with the aid of a magnifying lens. If I am going to need a magnifier, I would rather just use the un-pelleted seed. It is surprising how tiny the seeds can be and still be seen on a paper towel and transferred to a plant tray after germination. Baggie Method with Corn and Bean Seeds: I use the baggie method for almost everything except I modify it further with corn and beans. Dried corn and beans seeds don’t take up enough moisture from the moist paper towel, so I soak these in water for a couple of hours before putting them between several layers of moist paper towels in the baggies. Be careful of over-soaking beans because they can fall apart and rot if too wet. I usually experiment with a couple before committing an entire batch especially if it’s an unfamiliar variety. Canna “Nirvana” Baggie Method with Even Bigger Seeds/Nuts: I have used the baggie method on prunus seeds that needed a prolonged cold period (after a two-week wash to remove the fruit inhibitory chemicals) . Once their cold period was up, I switched the baggies to room temperature where a couple germinated. The rest went into pots outside where a few more germinated. I draw the line with the baggie method when I have a lot of large seeds because of space issues in the refrigerator. So right now, there are several hundred American Chestnut and Paw Paw seeds planted outside in a bed in hopes that Nature will be favorable to their germination. (The Paw Paws did have two weeks of washing before being sown to remove the fruit inhibitory chemicals). And since almost all nuts seem to benefit from soaking in water before being sown in the ground, the Chestnuts enjoyed a bath for a week, (On the topic of nuts: Don’t waste your time trying to germinate nuts bought at the grocery store. Those have been pasteurized or chemically treated so they cannot germinate.) Red Buckeye Flower. Seeds easily germinate outside after soaking in water for 2 weeks Hybrid seeds: Plant breeders can create intra-species hybrids that bring in the desirable traits of the different species. Occasionally, flower hybrids are made with species that have different requirements to degrade the inhibitory chemicals (depending on the climate that the various species originated). The one time I was aware of the different species, I looked both up in Dr. Deno’s books and did half of the seeds at the conditions for one species and the other half at the other conditions (and only one of the methods worked so I lost half the seeds). Usually, I just depend on the supplier’s germination directions and modify as needed to fit the baggie method. Hybrid vegetables are much more common, but since almost all vegetables readily germinate at room temperature after dry storage, the introduction of genes from another species does not affect germination with the baggie method. However, hybridized vegetables do raise interesting problems if you save seeds. The subsequent generations may revert back to the characteristics of the species the plant breeder brought into the mix. Usually this not a major problem except you may get disappointing results in your garden. For instance, seeds from that large, blocky hybrid bell pepper may grow plants with gnarly little pepper nubs (Been there, done that!). Occasionally, the subsequent generations may revert back to something you absolutely do not want: I’ve read that some squash family hybrids can revert back to a gourd-like fruit that is toxic; its also supposed to be really acrid tasting so its unlikely that anyone would consume enough to do real harm, but why take the chance having it in your garden? Further Reading: Dr. Deno produced “Seed Germination Theory and Practice” as a self-published book and followed it up with two supplements. Between the three volumes, he details the germination requirements of over 5,000 species. After his death in 2017, his family permitted the US National Agricultural Library to disseminate his books as scanned PDF versions. These are available at no charge at the following links: Seed Germination Theory and Practice (1993) The First Supplement (1996) The Second Supplement Each supplement builds on the previous version so you need to get all three if there is a particular species of interest to you. They are a wealth of knowledge. Also, there is lot more to Dr. Deno’s theories than I summarized here. [END] --- [1] Url: https://www.dailykos.com/stories/2023/2/25/2146375/-Saturday-Morning-Garden-Blogging-Vol-19-8-Seed-Starting-101 Published and (C) by Daily Kos Content appears here under this condition or license: Site content may be used for any purpose without permission unless otherwise specified. via Magical.Fish Gopher News Feeds: gopher://magical.fish/1/feeds/news/dailykos/