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My Surprising Nicotiana Trial Results

A border of 5 foot tall nicotiana after my interesting trial that I conducted to test various cultural methods to see if I could get better results from what is typically a ho-hum flower.

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 range of new and old Nicotiana varieties, some crosses and those with features I liked such as height or interesting colors.

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.

Nicotiana ‘Selected Night Flight’ were huge plants with flowers that became highly fragrant at dusk.

‘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? 

Nicotiana ‘Hot Chocolate’ delivered on the deep-brown color promise despite reviews I had read on-line. This was my absolute favorite nicotiana, perhaps of all time.

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.

Nicotiana ‘Hot Chocolate’
Nicotiana ‘Starlight Dancer’, a hybrid between N. langsdorfii and the Jasmine tobacco. Fragrant and floriferous, this made my list for growing again with its abundant blooms. It would be a great moon garden plant.

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.

Seedlings were all sown in flats or 4″ pots, using sterile Pro Mix and a light 1/7 inch coating of fine vermiculite.

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.

Under bright lights set to 16 hours and warmth (72° F) seedlings that were sown February 2nd grew quickly and were ready to transplant once they grew their second and third pair of leaves by March 3rd.

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

Young plants were provided the luxury of large, single pots to see if pot size would affect quality.

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.

Various sizes of pots were used. These are deep 8 inch root trainer pots that are 4″ in diameter.

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.

The plants set into 4″ deep pots quickly outgrew their pots, requiring an upgrade to 6″ or 12″ combo pots so that roots would experience no constriction, allowing plants to reach their optimum size. Plants also didn’t ‘bolt’ into bloom in larger pots, waiting more than a month longer before starting to send up florals stalks. Seedlings from the same seed tray that remained in 2″ pots were often already in bloom by then.

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.

Nicotiana ‘Starlight Dancer’ set into 6″ pots grew even quicker, with larger foliage and maximum root growth in comparison to other seedlings from the same seed tray that were being grown on in 2.5″ cells, which were significantly smaller and weaker.
All of these seedlings were started at the same time (Feb.2) but by May 14 matured and started blooming at very different heights.

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.

Newly set out giant plants along the greenhouse path.
Smaller plants, those grown on in 2.5 inch pots were smaller overall, reaching about 2.5 feet in the garden. The still bloomed well but were significantly less showy that the 6 foot giants that were grown in 12 and 14″ pots.

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.

Plants from the very same seed pot that were bring grown in 2.5″ deep cells were substantially smaller and weaker. These are closer to the quality and size one might find at a garden center. Final size once planted out was half the height of those grown without any root constriction.
The same seedlings that were planted in 10″ and 12″ pots (recycled nursery pots) were the largest. Clearly when roots are allowed to grow without any interference the plants do indeed grow much larger. This was the method used by estate gardeners a century ago. Single clay pots, spaced out on greenhouse benches, the giant plants were gorgeous.

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. 

The largest plants were eventually moved outdoors and planted along the greenhouse path. Not the ideal site, I found that plants were still too brittle as they had grown underclass for too long, so bamboo stakes were required (plus terriers like to rub their backs along the boxwood hedge. These were still spectacular while in bloom, taller than I was.

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 greenhouse walk had never looked so good, and just in time for our Garden Conservancy Open Day’s tour.
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Nicotiana ‘Perfume Mix; from Harris seeds also performed well, and the color palette worked nicely in the perennial border I call the Painter’s Garden”
Beauty in the perennial border a full month earlier than a typical display which allowed for some interesting combinations.

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