Over the past three years I’ve been growing various annual vines in containers, trying about 6-8 different varieties of the most commonly found annual vines, each year. As you may have discovered yourself, annual vines like morning glories while beautiful and easy to germinate, can, and do, grow too quickly and with such vigor that they can, and will, get out-of-hand often before they bloom. Yet other annual vines are more tidy and manageable. I wanted to see what vines were the most manageable, and which ones were the most beautiful as a container plant, and which ones are best left to the trellis or telephone pole.

I remember reading in an old gardening book once that one should always approach vines with caution. They are biologically coded to be opportunistic, but that makes sense once you observe vines growing. They are simply designed to race up objects quickly to reach the canopy so that they can get sunlight and attract pollinators. I was reminded of this while botanizing in western China in 2018 when I saw clematis growing on a hillside in the Himalaya, often nearly completely covering the horizontal limbs of evergreens – looking more like a snowstorm had dusted each fir tree with a coating of snow. Clearly, clematis are designed to ramble through shrubs and trees more than they are designed to climb lamp posts.

I grew all of my annual vines in 14″ deep 12″ diameter clay pots (from a discount store at $9.99 each). These were perfect as I could set in 8 or so 3/8″ bamboo stakes that were 5′ long along the diameter (starting by spacing them like the hours on a clock, 3:00, 6:00, 9:00. etc, or like cutting a pizza in to 8 pieces). I then would tie them at the top with twine to create a thin, teepee-type structure.

Knowing how your vine ‘climbs’ is helpful, as sometimes you may need to add bird netting or chicken wire – even wrap the entire teepee with twin if the vine climbs by using tendrils (like grapes or sweet peas), while other vines naturally twine around the support, such as with morning glories. Then, there are vines with do neither, like nasturtiums – especially the yellow-flowers canary vine, which sometimes use their leaf-stems to twine (the petioles) or they prefer to just tumble and creep over branches in the wild. These will require more help such as hand tieing new growth with soft yarn or garden twine to get things going.

I tried to focus on the most common annual vines that any of us can find on a seed rack or in a seed catalog, but I also tried a few more focused trials – particularly with sweet peas, and other annual lathyrus, just to see what they would look like if grown in pots. Out common cut flower sweet peas – Lathyrus odoratus, the Spencer varieties and the old fashioned cut flower sweet peas, which not ideal for growing in pots, did do well if the pot was larger than the 12″ pots I first tried for the more rare, or unusual species. I will say that the species surprised me with how small many of them were once mature, and how unique the foliage and even the seed pods were – often even more interesting than their flowers were. The only downside was that they bloomed early, and only for a week or two, then set seed and died. Not a long-live potted plant.

The cut flower types of sweet peas fared better in some 24″ clay pots and particularly the ones that I grew in an old 1940’s metal cooler (with holes drilled in it). These grew taller, on an 8 foot tall tomato cage, and did so well, that I may always grow some sweet peas this way.

An excellent choice for 12″ pots would be any of the Black Eyed Susan Vines, particularly the newer selections (like those found with registered, licensed names from brands like Proven Winners). All are fine, even the varieties you can start from seed indoors, under lights, but the better colors do seem to come from the newer selections. These not only grow quickly, but so aggressively that you will only need one per 12-14″ pot. One plant will send out dozens of shoots and quickly cover a 5-6 foot tall teepee. These tend to always look neat, though once they reach the top, you will need to retrain them down or prune them often. They can quickly take over any nearby teepees or shrubs if they touch them.

Morning glories, and their relatives may seem like a natural first choice, but proceed with caution as most will out grow a pot before mid summer, especially the species. I will say that the Japanese varieties (called Asagao in Japan) do make excellent potted plants (you know, the striped ones, and even many dwarf and mutations available on eBay). There is an entire culture around growing these in Japan, where, like bonsai, they are grown in smaller pots and pruned heavily, often keeping teepees to only 14″ tall. I’ve grown many morning glories this way, and while the method even works with Heavenly Blue and other common varieties, it’s labor intensive as you know how fast morning glories can grow. It’s best done with the variegated-leaf Japanese varieties, however, but that merits another post.

There are some species of Morning glory however, which I did try. This year, I grew the wild species Ipomoea hederifolia var. lutea , a species that was completely new to me which was incredible, blooming all summer long, delighting the hummingbirds and forming a cloud of tiny, tubular yellow blooms that were about 1″ in diameter. The only problem was that the vine quickly outgrew my 14″ deep clay pot by mid-June, so I had to plant it out. Sliding the entire root ball and bamboo caned, which by July 4th were already completely covered with foliage and twining stems into my shrub border where it completely covered a Black Prince, eventually killing it by smothering it, but totally covering it with a cloud of yellow blooms that made the effect something that I want to repeat every year. There is a red species now that I want to try next year, which seems similar, I. coccinea.

The Spanish flag vine, has always been a favorite of mine. I mean, cmon, ombre! It almost doesn’t seem real, but it’s a good candidate for pots as long as you know that it won’t bloom until late summer, and it too can get a bit out of hand, though not as aggressive as let’s say a regular blue morning glory might be, even though it’s related. Once taxonomists listed it as Mina lobata, but it sits firmly in Convolvulaceae, the Morning glory family, and is properly known as Ipomoea lobata.

Some of my favorite annual vines remain the most common. Sky blue morning glories, like ‘Heavenly Blue’ is pure nostalgia for me, as it reminds me of my dearest aunt (Aunt Ann) who lived in New Jersey, and grew it on her chainlink fence behind her home. It was a tiny, long garden in Trenton, but full of plants., such as was my grandfather’s garden was nearby also in Trenton. That was where I first saw a passionflower vine growing, behind my grandfathers chicken coop. He was nearly 100 years old in the early 1980’s, and didn’t speak much English, but he wanted to show me the passifloras when they were in bloom. I should mention that they too are good for large containers, but I didn’t include them here as they aren’t true annuals (even though we grow them that way up north).

I have to admit that the finest display came from the Purple Bell Vine, Rhodochiton atrosanguineus. IT used to be hard to find, but I find seedlings occasionally at some local Boston area nurseries. Like most vines, it’s not going to be in bloom when you find it available as a seedling, and young plants can look rather weak and unpromising. All I can say it get it, if you find it, for few plants put on such a show. My towers were so attractive this past year that I set them around the garden as objects, even loaning a few to a clients garden photoshoot for a story in Architectural Digest. They are that attractive. You can grow them from seed, but it takes some patience.

Sow seed in February, under lights and keep them warm. Transplant carefully into larger pots in spring, and eventually set the young plants into a big pot such as my 12 to 14″ long toms with 5′ bamboo canes. It’s a twiner, which helps, but every bit of this plant looks lovely, from the burgundy backed foliage to the amazing flowers that almost defy description. It starts blooming when young, so it just about always looks good. Best to start with new plants every year, though, as it is hard to winter over successfully in the north.

The Love in a Puff Vine (Cardiospermum halicacabum) is a true old fashioned, if not heirloom plant that is fun to grow for its puffy, inflated seed pods that each contain a few of their distinctive seeds – each with a tiny beige heart them, hence, where it gets its name. Granted, it’s not a vine for everyone, as it can look weedy or too casual for many. I love it, as I’ve seen it grown to great effect in urns set into the center of an herb garden at an estate in the Hudson Valley, and on a trellis in a friends garden. You just have to be prepared for rampant growth, which is graceful, and know that one doesn’t grow this plant for it’s inconspicuous tiny white blooms, but for the seed capsules, and the overall effect – a tangle of stems and foliage, which can look attractive in the right sort of setting.

Side by side, pots of vines displayed in a row can also be attractive. Each year I line a few walks and paths around the garden, or leading to the greenhouse with potted vines being trained onto bamboo teepees. I allows me to grow a number of vines in a small space, and I know that I can cut back any that get too unruly. In pots, the blooms are brought to eye level, but I have to say that more and more, I am attracted to the foliage than I am to the flowers.

Nasturtiums are naturally vines in the wilds of South America, but most have been bred to be shorter plants, yet a few remain – true heirlooms and worth playing with, to add something different to the garden. You may already know that I collect many of the tuberous tropaeolums from the Andes, and grow them as winter-blooming vines in my greenhouse, but there are some very easy annual tropaeolums, from the veining nasturtiums (like the one sees every spring at Boston’s Isabella Stewart Gardner museum) or the overlooked Canary Vine, which you can still find in good seed catalogs.

Easy to grow, the Canary Vine (also sold as Canary Creeper, or the Canary Bird Vine) has large seeds like the nasturtiums you already love, but it is an aggressive grower, and probably not my best choice for a container unless you have a bigger one – let’s say 24 -30″ wide. It dislikes drying out in summer, which can kill a vine in just a day (believe me, I know) and the foliage can yellow practically overnight if you let it dry out. The vine can be very effective if grown in a large pot as long as you have something for it to climb on. I’d say that it’s better if planted into the ground, though. It’s not a twiner, no tendrils either, so it’s best climbing through twigs or over a shrub. I once planted a big parrot cage that we had left out on the deck (when our Parrot Kojo flew away). WE hoped her would return, but a canary vine took off in a large pot, so I set it inside the parrot cage (seemed ironic at the time). It completely covered the cage which was about 4′ x 6′ on rollers, and became quite the spectacle.

Another morning glory relative which is slightly better behaved, is the Cypress vine, or Cardinal Vine. Closely aligned with Ipomoea x multifida, and related to the red flowers I. coccinea, this annual vine will quickly cover a tower in a few months from a sowing in late May. I sow all of my Ipomoea species and selections near the end of May, as they are rapid growers, and really don’t need a head start. Do know that in the south, and in warmer zones many of these morning glory relatives can be considered to be invasive, as they self-seed and can spread, so check your local restrictions before planting.

Vines in pots will be like trying to raise three teenage brothers. They will fight with each other, and try to dominate each other constantly getting into trouble. Try your best to raise them independently but sternly, training them almost every day (as they’ll forget) and then enjoy the results of your labor once they reach maturity and bloom. It’s may seem like all is lost, but be firm, and don’t be afraid to control them a bit.

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We, gardeners, are all familiar with the genus Nicotiana. While we may not know that was named for Jean Nicot, a French diplomat in 1559 . Mssr. Nicot first saw a tobacco plant shortly after it arrived in some plant collections made in South America a few years earlier. Convinced that is had medicinal properties, he presented the plant to the French queen, Catherine de Médicis, as a remedy for her headaches. Apparently, her resulting endorsement (which frankly might have been more of an addiction than anything else) made Nicotiana tabacum quite famous. It didn’t take long for the famed tobacco take hold of those who loved it, , and cultivation spread across Europe and shortly later, back to North America, where it was already a well-known drug and ceremonial smoke to indiginous tribes.

I decided to trial a few newer selections this year after reading about how older selections were once widespread conservatory plants in the 19th century. This interested me, as I never thought of Nicotiana as a potted plant, at least as a conservatory plant. Older books often talked about estate gardeners growing individual plants to perfection for spring and summer displays in glasshouses and conservatories (think: Isabella Stewart Gardner Museum). You know, I love that sort of challenge.

After some (well, lots) of research, I found that the plant was also recommended for culture as a potted display plant in cold or cool greenhouses – so now I was interested. 

Nicotiana was typically a plant that I grew from seed only occasionally. I more likely would just buy a few plants from good growers or pick up a few 6 packs if the colors interested me. If I sowed from seed, it would be a more casual affair, sprinkling a few seed (always thinly, I knew that much) in a pot, pricking out and potting up later in spring for a few spots in the garden. They always seemed to perform well, but honestly, I could never say that I fussed with them or even followed any complex instructions other than what I already knew (bottom heat, bright light, and don’t start too early.

What caught me attention in one book was that the author suggested that I sow seeds in November or December for blooms in April. Of course, this was a British book, and was informing those who owned cold greenhouses in the UK who wanted early display material, but hey – I had a cold greenhouse. While I live in New England (not Old England), it should still work.

I selected a few varieties to sow very early (at least for me), in December.Since light levels are low in winter here, and the greenhouse is too cold.

‘Night Flight’ appealed to me because of it’s size and promised 6′ height, something I tend to look at first as I like tall annuals. It’s was also said to have intense fragrance, which was so true that it surprised me many evenings, as I looked for “what is that smell?” believing that it was indeed a jasmine. I am rarely that fooled. ‘Night Flight’ is also unique from a performance perspective. It’s truly night blooming, opening in the evening when it’s highly fragrant, and the blossoms also lift up at that time as if to emit more scent. I would often think that they were wilting during the day, and the lack of daytime fragrance often caught me off guard when I asked guest to smell it at noon.

This is hybrid between Nicotiana alata and Nicotiana forgetiana. ‘Night Flight’ was offered by Select Seeds, and it seems only by them, so maybe it’s proprietary to them? 

I’m a sucker for brown flowers, so I had to try a selection called N. ‘Hot Chocolate’ as well as N. ‘Bronze Queen’. Both, selections that include my famed, self-seeding green-flowered N. langsdorfii in their genes.

Another N. langsdorfii crosss called N. ‘Starlight Dancer’ (N. langsdorfii x N. alata’) a white flowering variety with loads of blooms made my January list. N. alata itself, is often called ‘jasmine tobacco’, so yeah – fragrance was promised. N. alata itself is a long-time favorite around here. ‘Starlight Dancer’ is a relatively recent introduction, a hybrid from the Netherlands. It can grow up to 4 feet tall so yes, height appealed to me. 

I did add at the last minute, two popular shorter-flowering species, purely for beauty. The clear purple strain ‘Perfume Deep Purple’, which is an AAS winner. (N. x sanderae), and N. ‘Lime Green’ with similar heritage. After all, I am not a prude. One must have simple, awesome beauty. These bloomed later as I sowed them in April and May, but they lasted until…frost.

I started these under lights in the house. Contrary to what many winter-sowing folks believe, Nicotiana do not require any stratification or cold temperatures to germinate. They may re-sow or self-sow, surviving a harsh winter, but they certainly do not want nor need feezing temperatures. Seed will not germinate until the soil temperatures reach 72° F or higher. 

By December and later, January sown seedlings emerged within a week. I covered seed with a light coating of fine vermiculite as soil can dry out in winter quicker, though seed sown outdoors will germinate best if sprinkled on the surface. Seeds are tiny.

I knew that most species of Nicotiana look similar when not in bloom. Any differences are subtle and don’t appear until the plants begin to form flowering stems or buds. This means that you must label seed flats as it’s easy to get confused. I discovered that I had to label individual pots, as I grew the varieties and even then, I have to say that things got mixed up so I created a parking lot of confused, unmarked pots. If you’re growing a few under lights, this won’t be a problem if you keep individual pots set inside of another flat.

It is also worth noting that nicotiana plants, especially seedlings but also young plants have surprisingly brittle and clingy leaves that are sticky to the touch. The stick to one another and will rip or break easily if you don’t take great care when separating them.Another reason to sow seed thinly, and to repot when the seedlings are still tiny. And believe me, they are tiny. I over-pot them, meaning that I left out a 1/2 inch wide seedling and set it with the tip of a plant label into a 3 or 4 inch pot. 

Nicotianas are hungry plants. too. I used both a balanced Osmocote, and a liquid fish emulsion weekly. As I often do, not only do I look at old books, I compare those with contemporary science and research. One of the best places to look for information are on professional grower or culture sheets (just Google Nicotiana Culture Sheet). I used those from Florinova, but most provide good basic information in regards to temperatures and fertilizer. Be prepared for these pdf’s to suggest ridiculously high concentrations of fertilizer, which of course, I don’t follow, but it’s helpful to know if a species is sensitive to magnesium or an abundance of nitrogen. All too often I see unfounded recommendations on sites such as “just use seaweed” or “Epsom salts will do the trick”. Luckily, Nicotiana aren’t that fussy, and either a balanced feed (Miracle Gro) or even a fish emulsion will work fine. Pro’s use a 20-10-20.

Temperatures should be warm during germinations (75° is ideal) and 70 while growing one when young, so I kept seed trays under lights until mid-march. After that, 65° F is ideal and while nighttime temps dropped to 50 in the greenhouse by then, once transplanted, all seedlings were kept in the greenhouse. l

Plants were all grown on in progressively larger pots as soon as roots started to emerge from the bottom. As spring progressed, and the greenhouse became warmer and the days longer, plants started to grow larger and faster. I completely understand that not everyone has the luxury to grow annuals in this way, but it does teach us that with care, some of even the most common annuals can excel if grown carefully at home, even if you start them under lights in your garage or cellar and just sow them later.

Pot size was key to success. I learned that seedlings must be transplanted young, before they become too large (before three pairs of leaves). If you want incredibly tall and stunning Nicotiana, avoid letting roots touch the edge of their pot. I know this sounds crazy, but if you’ve observed self-seeded plants in the garden, you can clearly see the difference. Once nicotiana become pot-bound there is no recovery. Plants will be spindly and they’ll that bloom too early, on hopelessly short stalks.  Unfortunately, that’s what we typically find sold at retail, and no cutting back, pinching or spreading the roots will help those recover to match the performance of those grown without root binding. I kind-of knew that, but never really believed it.

I upgraded some to 8″ nursery pots, and other were kept in 6″ square plastic pots. A few of the ‘Night Flight’ variety though began to meet the promise of 6 foot plants, so I moved them up to 12″ clay pots, one per pot – clearly overkill, but they responded so well, that I started to move more plants into larger pots.

I started to run out of room, but the results of moving plant up into larger pots did confirm what I had expected, and what the old books all advised – that Nicotiana will sulk if kept pot bound (again, think about those nursery 6 packs where the root ball is entirely white with roots). Nicotiana are also sensitive to plant growth regulators, but I also know that commercial growers could not possibly deal with 4 foot tall seedlings. We’ve all seed nicotiana in-bloom at the garden center in 6 packs, often that’s all we can find, but while they perform just OK, I knew that self seeded ones were always better. I wasnt all that surprised.

I did pinch a few back, which surprised me that it was advice in these old books, and while the final effect wasnt as elegant as the first, tall single stem, the plants that I did pinch did produce side shoots and many more blooms. I might pinch if I planned to set out plants into a mass planting in a border, but I tend to like the natural look of unpinched.

Clearly I grew too many, but the results were interesting. Most noticible were blooming size and overall plant habit in relation to pot size. All species and varieties bloomed weeks earlier on significantly shorter stems if they were kept in 2″ pots. The plants that were in the largest pots continued to form rosettes of gigantic leaves for many weeks before they started send up their first main flowering stem. These stems did reach up to 6 feet tall as promised, looking more like those self-seeded plants that would pop up in my garden.

In the garden, these more mature plants bloomed profusely in June and early July, but they did peter out by the end of July. A few that were cut back did rebloom, but the effect wasnt even close to that first rush of bloom. My later sown plants (the purple and lime green) bloomed well all summer. In the end, I again noticed that my self-seeded forms were still the most agressive and strongest growers, but they didnt emerge until mid to late June, which tells me that I could sow outdoors as late as the summer solstice in June. All the plants that were started in the greenhouse produced tremendous but early shows, but they all required staking and failed to continue after mid-summer.

All of this tells me that we shouldn’t start Nicotiana indoors at all unless we want early blooms. We should not use the winter sowing method as that is just bad horticulture, but we could sow seeds in seed trays and pots in June, which is when they really want to germinate. These grow very quickly. I will do both, sow some under lights in January but primarily for early greenhouse color in April and May, and for some spectacular outdoor beds in June and early July. My second crop will be sown outdoors in June, that will replace those that are fading. 

I will add that all of my methods this year were usable and produced far better results than any plants that I bought at garden centers or nurseries. The only exception are those that I buy from a few specialty growers (like Bunker Farm in Vermont or Walker Farm Stand also in Vermont) who truly know what they are doing as they sell small seedlings in larger pots or 6-packs. Maybe you have a grower like that near you, or better yet, order some seeds now and experiment yourself!

By May, I could tell that pot size and fertility affected performance. The seedlings that were transplanted into standard 2.5″ modules, pots or six packs were all starting to bloom even though they were less than a foot tall. The seedlings transplanted into 3″ pots weren’t much better, but had foliage that looked healthier. Plants in 6″ pots (one per pot) looked far better, were at least 4 feet tall and were not even beginning to form flower buds yet. Plants in 12″ pots had foliage as large as cabbages, and were forming central stalks as thick as 1″ in diameter. I’ve never seen such a difference with an annual.

The post My Surprising Nicotiana Trial Results appeared first on Growing With Plants.

My last post, (which was surprisingly this past February) proves not only how busy I’ve been, but how time can fly by. First, just so you know – I’m mostly posting to my Instagram account lately (mostly everyday). So if you need more updates than my blog offers, follow me at @matt_mattus on Instagram and see what’s happening in the garden, greenhouse and sometimes in the kitchen.

My 2022 trials we as obsessive as usual, but perhaps even mores this year as we were honored to have our garden included as a Garden Conservancy Open Days garden in May. If any of you have participated in this event, you know how time consuming preparing ones garden for a tour can be. OK, I know it’s already October, but even though our tour was in May, it was well attended (sold out in 24 hours) and for about a month and a half after that, we were just wiped out. Then, summer hit full-on, with drought, heat and then COVID for both of us (we’re fine, just mild but exhausting symptoms) and the one garden client we have required much attention for a big photoshoot – more about that later. Anyway, time flies, and I don’t think that I’ve ever skipped so many months posting to this blog. Maybe blogging itself is changing as well, in a world of faster social media like Instagram? Please let me know you still read and follow this, or if you prefer a different medium (Podcast, video, something else), as that will help me decide where to share.

I’ll bet that very few people grow, if even care about the old fashioned annual flower called Salpiglossis or bearded Tongue, but to follow through from my last post, this year I decided to try various techniques and methods, most of which challenged what one will find on the internet or even in books and seed catalogs. Cultural information for more uncommon annuals is often incorrect – I really don’t know why other than this information is often second or third-hand. I would bet that many garden writers research via the internet, Google search or via the latest books, and to be fair, many freelancers are on a tight deadline. I’m really not trying to be critical here, but instead – simply honest. My guess here is that some cultural information is just passed along via respectable sources (university sites, seed companies and in gardening books) but rarely are they challenged or researched deeply. My findings may still be incorrect, but after three years, I am getting extraordinary results with a few annuals, and this Salpiglossis trial is confirming some surprising findings.

Briefly, Salpiglossis information from seed to flowers often starts with germination advice that is contradictory. Germinate dark, surface sown, sow seed 1/4 inch deep, seed needs light or complete darkness to germinate. For years I used to follow directions from a very trusted book on raising annuals – I covered surface sown seed with tinfoil, kept trays warm until seeds germinated. While I don’t know where this information originated, it may have come from early seed collectors who noted that in its native habitat, Salpiglossis sinuata grows in a unique coastal climate where the marine air is cool, frequent fog and overcast in winter, but the seed drops down onto a rocky surface where it is shaded. I should note that my research is certainly flawed, I usually try to look backwards through history to see where a plant is native to, I make notes about the climate there, and how it relates to the plants natural cycles. Salpiglossis is unique in this case. Still, there is no excuse for such contradiction when it comes to germination advice – and some seed packets from large seed companies offer contradicting information printed on the same packet in different locations.

The above image shows my reward for following directions, both from two old books (reviewed in my previous post). I couldn’t believe that my tiny seedlings would grow -with great care, but not all that much effort – into what the books once promised – 4-5 foot tall plants, some as tall as 6 feet tall. If you’ve ever tried growing salpiglossis in your flower beds from seedlings bought at nurseries, you know how unusual this is. I wanted to figure out why nursery plants often topped out at 1.5 feet tall – maybe 24″, and what were we doing wrong.

I used a number of sources for both seed and cultural advice, but the 2021-22 seed catalogs offered only a few varieties of salpiglossis. It seems the few breeders only introduce a strain that is interesting every few years, and most seed companies default back to the old standards. This is understandable as so few of us grow salpiglossis. It’s not a great cut-flower, and a good majority of home gardeners don’t even know what it is, let alone have actually seen a plant in bloom before. Thumbnail photos are often misleading, and many might just write it off as another petunia-look-alike (it is released, however, as salpiglossis is organized within Solanaceae, along with petunias and tomatoes).

I should also add that while I had success growing salpiglossis following the cultural advice often found on-line or in books (surface sow, but keep trays in complete darkness until germination), I always found that even if I catch the seedlings just as they have germinated, they would still be too elongated and never seemed to recover. Not to mention that I always wondered why such advice existed, as it just never made sense. I found that the very old books (19th century) often suggested covering the seed lightly, but my mind was changed once I started downloading professional grower guides supplied by the major seed suppliers (where seed catalogs get their seed from). These guides are written for commercial growers – often plug growers or wholesale nurseries who depend on raising healthy crops of bedding plants. While often not helpful for home growers, as these can be complex or offer information such as feeding schedules that are in code, or parts per million, they do offer some valuable bits of advice, one of which was soil depth for seed sowing which was 1/8 – 1.4″ deep. Not surface sown.

I germinated all 5 packets of seeds indoors, between January and early March to see if timing made a difference. seed pots and flats where sown thinly, covered with fine vermiculite at about 1/8 inch deep, and set under high intensity, full-spectrum LED lights in a spare bedroom. The warm, indoor temperatures were beneficial and it’s a method I’ll do again as it worked much better than heating mats outdoors for me (maybe because the temperature differential from day to night was measurable, and not consistent.).

Professional grower sheets provided another clue, and that is as with snapdragons and sometimes pansies, the seed trays and pots were allowed to dry out between watering. This is a critical step for salpiglossis, as they tend to be weak rooted, and dry medium forces roots to go searching for water, and thus, nutrients. Drying out between watering to a point of slight wilt also stimulated seedlings to grow denser and produced stockier seedlings.

Fertilizer was also key, as salpiglossis has some demands and sensitivity as with petunias and snaps. I used the recommended amount of a Cal-Mag feed (you can find it under the Peters or Jack’s Brand on Amazon sold as Petunia Feed. It’s hard to find at retail offered in small amounts, as most sources only offer Cal Mag in 50lb bags for professional growers. It’s a must for growing snapdragons, pansies and petunias). You an find more info about the benefits of using a cal-mag feed here https://www.gardenmyths.com/cal-mag-plants/ and you can read here https://www.greenhousegrower.com/crops/petunia-finished-production-tips/ about why snapdragons and petunia seedlings require cal-mag feeds.especially if you use an acidic potting mix (peat based) or coir based. If you’ve ever tried to grow snaps and found the leaves starting to yellow while still very young, this is probably why. All the Miracle-Gro in the world won’t turn them green. (note: Not all flowers or veg need additional calcium or magnesium, and while these elements aren’t added to regular fertilizers, and not always needed, I’d avoid using home made solutions (such as Epsom salts and eggshells). Epsom may work if you can measure it precisely, but it still will need calcium to work well, and egg shells aren’t a good choice for seedlings due to the year, or so, required for eggshells to decay and convert to usable calcium).

Another good tip came with when and how to transplant. Salpiglossis dislike root disturbance or better yet, root restriction. They like a free root run, and seedlings will sulk and bolt if pots become root bound, as in nursery 6 packs – one of the main reasons why I think nursery plants in small modules are often don’t perform well. I can understand why nurseries grow their annuals this way, it’s easier to grow all of ones crops the same way, but unlike their kin snapdragons or petunias, where extra fertilizer applied to even tiny pots, will still produce strong, yet root bound, seedlings. One benefit of keeping salpiglossis in small modules rootbound, is that they’ll bloom younger, which obviously has its benefits as most consumers want to buy a plant in bloom, but buying a salpiglossis 6 pack with flower buds will do you no favors. They’ll bloom for a few weeks, and maybe reach a foot or so tall, but then that’s it. I wanted to see if I could produce those 5 foot tall plants with dozens and dozens of flowers that the old gardening books promised. As you’ll see, I did, but it took the luxury of greenhouse space, and daily coddling.

I potted young seedlings up into larger pots as soon as they formed their first or second pair of true leaves. The older texts suggested a final pot size of 9″, so I began transferring into 3″ and 4″ pots at first, so that I could easily dry out the pots between watering, but then moved them up to 6 and 8″ pots. I thought that these might be the final size, but plants began to grow so large that I decided to upgrade 12 of them to 12 and 14″ deep clay long-toms. I used Pro-Mix BX as my primary medium, and continued a seeking Cal Mag feed if I could dry the pots out slightly (this depended on the weather). I quickly learned that the larger the pot, the better the results, but what surprised me was that while plants were growing tall and branching well in the largest pots, in the smaller ones, and especially those seedlings that I kept in 2″ 6 packs, that were root bound and fed the same diet, they began to form flower buds and bloom early at 9″ tall. These looked more like the typical seedling I would find at my local garden center.

Clearly the best results came from plants in the largest pots. I did pot some containers with 3 seedlings, but these didn’t grow as large as those did in the 14″ pots. Kept in the greenhouse, the leaves grew lush and large, requiring 5′ bamboo stakes one the central stem began to extend. I pinched some, which was advised, but found that the most elegant look came with those that were not pinched, and it seemed, just as many blooms. I relocated some plants outdoors around June 1, but that subjected them to an infestation of leaf miner, that ruined many leaved with their winding paths, just like spinach that was planted nearby. I removed most of the leaved, and moved all plants back underclass where the seemed to not mind the high heat on sunny days (near 100° F) if watered daily.

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