Flowering trees and nitrogen

[Mycin]

The traditional wisdom suggests that flowering trees will yield optimal blooms when fertilized with a low nitrogen fertilizer towards the end of the summer, through fall. The explanation provided is that higher nitrogen will result in more vegetative growth and less flower budding. I would have chalked this up as an old wive's tale, but I've heard it repeated by more than a few respected bonsai growers. On the other side, I'm hearing more and more people say that next year's buds are being grown now and high nitrogen will help these very buds develop. Not quite sure what to think.

Right now I'm using Peters 20-20-20 and would prefer not to buy a seperate "bloom promoter" fertilizer for my one Chaenomeles but if that's what would be best I'll do it. FWIW the Chaenomeles is developed, I'm just looking for maximum fruits, flowers, and ramification--in that order

 

[BonsaiWilderness]

Wow I did not know that!

 

[0soyoung]

The traditional wisdom suggests that flowering trees will yield optimal blooms when fertilized with a low nitrogen fertilizer towards the end of the summer, through fall. The explanation provided is that higher nitrogen will result in more vegetative growth and less flower budding. I would have chalked this up as an old wive's tale, but I've heard it repeated by more than a few respected bonsai growers. On the other side, I'm hearing more and more people say that next year's buds are being grown now and high nitrogen will help these very buds develop. Not quite sure what to think.

I have troubles with that conventional wisdom, as well. In fact, I dismiss it as BS while waiting for it to be convincingly demonstrated otherwise.

We do know (from botanists) that flower buds are just a vegetative buds that were somehow switched into becoming a flower bud. Once this happens it never goes back (i.e., flower buds do NOT revert to being vegetative). So, we can say that once it is a flower bud it doesn't matter what you feed to the plant, it is going to be a flower or it is going to be dead. This is easily verified to be true by any gardener once they have learned to recognize the fatter flower buds.

The mystery is what it takes to make the metamorphosis happen but it isn't simply and maybe not even a lack of nitrogen. Flowering competence or age is one universal factor. Then it depends upon the species, but generally involves the set of leaves closest to the bud which sense the light color and day length, among other things (so, if you do not want flowers, simply remove those leaves). Commonly, flowering woody trees/shrubs set flower buds after the passage of the summer solstice. Many also require vernalization or a winter chilling time to fully develop (lacking this the buds die).

There is some evidence that flower induction involves a reduction in gibberellins transported to the apical meristem. There are plant growth regulators that suppress gibberellins and which seem to have positive effects on flower production. There may be an indirect way in which gibberellin synthesis is inhibited by nitrogen availability, but flowering occurs naturally without manipulation of mineral nutrition.

 

[Shibui]

I use high N fert through spring and summer but switch to 'flowers and fruit' type fert from late summer for the flowering trees. It does seem to help with promoting better flowering.
One of the problems with assessing efficacy is that so many other factors play a part in flowering and some plants don't flower well every single year so people playing with fertilizer can be misled.

 

[Forsoothe!]

I too, call BS on low N helping flowering. High P on the other hand may or may not contribute to better flowers, but is only necessary, IMHO, if the fruit is crop-like in size. It takes a lot of everything to grow big fruit. If you don't want big fruit, as in bonsai, high P is also unnecessary and probably unhelpful. IMHO.

I use 20-20-20 and expect the surplus of anything to leach out, just like the part I want in there leaches out. While it is possible and probably good to customize fert formulae to individual plants, that goes out the door once you get to some number of plants that's hard to count. If you can count them, you don't have enough. I have enough.

 

[Mycin]

I have troubles with that conventional wisdom, as well. In fact, I dismiss it as BS while waiting for it to be convincingly demonstrated otherwise.

We do know (from botanists) that flower buds are just a vegetative buds that were somehow switched into becoming a flower bud. Once this happens it never goes back (i.e., flower buds do NOT revert to being vegetative). So, we can say that once it is a flower bud it doesn't matter what you feed to the plant, it is going to be a flower or it is going to be dead. This is easily verified to be true by any gardener once they have learned to recognize the fatter flower buds.

The mystery is what it takes to make the metamorphosis happen but it isn't simply and maybe not even a lack of nitrogen. Flowering competence or age is one universal factor. Then it depends upon the species, but generally involves the set of leaves closest to the bud which sense the light color and day length, among other things (so, if you do not want flowers, simply remove those leaves). Commonly, flowering woody trees/shrubs set flower buds after the passage of the summer solstice. Many also require vernalization or a winter chilling time to fully develop (lacking this the buds die).

There is some evidence that flower induction involves a reduction in gibberellins transported to the apical meristem. There are plant growth regulators that suppress gibberellins and which seem to have positive effects on flower production. There may be an indirect way in which gibberellin synthesis is inhibited by nitrogen availability, but flowering occurs naturally without manipulation of mineral nutrition.

Great info. Ok I'll keep fertilizing it like everything else then. It's a little relieving knowing that this element of growth is largely out of my control, truthfully.

The one factor that people seem to agree on is the temperature: a colder, harder freeze yields better flowers on many fruiting trees.

 

[Mycin]

I've heard of a few plants putting out flowers when sick as a last-ditch effort to propogate. Maybe low nitrogen feeding "stresses" the growing tree somewhat, eliciting a similar response?

 

[Mycin]

While it is possible and probably good to customize fert formulae to individual plants, that goes out the door once you get to some number of plants that's hard to count. If you can count them, you don't have enough. I have enough.

Assuming you had sufficient help and money was no cost - how many formulas would one really need? Seems like an All-purpose and an "acid-loving" ought to cover it really, no? Unless you're talking about tinkering with different concentrations, different fertilizer schedules, supplementing w ancillary stuff (humic/fulvic acid, kelp, etc)

For discussions sake - would you please care to elaborate?

 

[Forsoothe!]

Assuming you had sufficient help and money was no cost - how many formulas would one really need? Seems like an All-purpose and an "acid-loving" ought to cover it really, no? Unless you're talking about tinkering with different concentrations, different fertilizer schedules, supplementing w ancillary stuff (humic/fulvic acid, kelp, etc)

For discussions sake - would you please care to elaborate?

Actually, I am found out. I have one basic 20-20-20 liquid plus Superthrive, Sprint 138, Epson Salts, fulvic acid, kelp and humic acid that I goose with Copperas for most trees except lime lovers, of which I can't think of one. I also use 20-20-20 granular and Aluminum Sulfate granular top dressing after repot for long term feeding. My potting mix includes Jersey Green Sand Meneffe Humate and bone char. If I had unlimited help, I would do the same anyway. I substitute 10-50-10 on my vegetable garden and trees ready to bloom. I also use Bayer 2-in-1 or 3-in-1 at least once a year, but I ignore the fert aspect as minor.

 

[ABCarve]

Interesting subject! It seems as though each manufacturer of fertilizer offers a low N product for flowering purposes. Are they just hype? Another product to buy and make you feel good? Possible.......
I want my wisteria (just pruned) to stop vegetative growth as it will continue as long as temperatures allow. On the other hand, hamamelis stops vegetative growth fairly early.

 

[ABCarve]

Thinking some more........I have a flowering quince that puts out a profuse amount of flower buds but less than half of them actually bloom.......they just fall off.

 

[Kadebe]

Actually, I am found out. I have one basic 20-20-20 liquid plus Superthrive, Sprint 138, Epson Salts, fulvic acid, kelp and humic acid that I goose with Copperas for most trees except lime lovers, of which I can't think of one. I also use 20-20-20 granular and Aluminum Sulfate granular top dressing after repot for long term feeding. My potting mix includes Jersey Green Sand Meneffe Humate and bone char. If I had unlimited help, I would do the same anyway. I substitute 10-50-10 on my vegetable garden and trees ready to bloom. I also use Bayer 2-in-1 or 3-in-1 at least once a year, but I ignore the fert aspect as minor.

Isn't this like Herr WP's nutrition regime... nourishes with different fertilizers and a lot... the tree knows what it needs and only takes what it needs

Attention... if you apply this also watch the other videos about substrate and watering!!!

 

[Wires_Guy_wires]

I have delved into this in the past. P+K fertilizers are used to produce fruits and increase their weight, their brix levels and overall development. These P+K nutrients are given when the fruits start developing; during and after flowering. High boron levels contribute to fruit size too, so also check your micro-nutrients.
For the development of primordial flower buds, a plant needs a bunch of nitrogen as well. Because flower development isn't possible without building blocks, and nitrogen is one of the most important building block for plant cells. Flowers usually don't produce much sugars and starches, they hardly photosynthesize, they're more of a converter of input material. This means they need enzymes, proteins and functioning biological systems which all need N, C, H, and O.

If you're growing a plant for its flowers, keep nitrogen equalized.
If you're growing a plant for its fruits, up the P and K during flowering and fruit development but don't stop dosing N entirely; if the plant has to get the N from other structures, it'll eat up its own foliage to get it. -> see any cannabis or tomato plant that receives only P+K nutrients, they go yellow from bottom towards the top. An outdated concept; crippling your plants to increase yields.. Solar panels increase yields, if the plant eats them all.. Then it can only draw energy from reserves. It needs N for those solar panels, both for upkeep and development.

 

[sorce]

The goal is not NPK, it's IPT, items per ticket.

It's just another way to get you to spend more money at one time, that time is every time you are standing in front of the product.

Who doesn't like to have 3 pretty color boxes on their shelf too? Everybody does!

Oh, it's BS alright!

Sorce

 

[ABCarve]

I must say I’ve never used the “bloom” products and have plenty of blooming other than the aforementioned mentioned quince, which may not have to do with nutrition. I’ll also say I have used Superthrive and can’t see any difference one way or the other. I still put it in when repotting cause it makes me feel better about beating up my plants.

 

[Clicio]

I have used Superthrive and can’t see any difference .

I guess Superthrive is a moneymaking scheme never scientifically proved to work with bonsai.

 

[Forsoothe!]

Everything that grows needs N. The amount of growth is dependent upon the amount of N available. I feed regularly, but not a lot or often. It is my intent to have more growth than "natural", but not a lot of intense growth. I don't want "big" or "fast" growth, mostly I feed to nurture next year's buds this year. I want to feed enough to make up for the foliage I remove in the bonsai process. Since a lot of that foliage removal is to produce increased numbers of smaller foliage, heavy feeding would thwart that and so I avoid heavy feeding and/or too often. Mostly, I like to think I am maintaining what is rather than puffing up trees. While everyone wants trees to get more mature, and mature is bigger trunks, nebari, etc., I want my trees to maintain the same profile and get "more mature" within the existing profile. Strong growth is problematic to maintaining a given design. In fact, the more refined a tree design is, the more difficult it is to maintain it without it negatively affecting the tree's health.

 

[Mycin]

Actually, I am found out. I have one basic 20-20-20 liquid plus Superthrive, Sprint 138, Epson Salts, fulvic acid, kelp and humic acid that I goose with Copperas for most trees except lime lovers, of which I can't think of one. I also use 20-20-20 granular and Aluminum Sulfate granular top dressing after repot for long term feeding. My potting mix includes Jersey Green Sand Meneffe Humate and bone char. If I had unlimited help, I would do the same anyway. I substitute 10-50-10 on my vegetable garden and trees ready to bloom. I also use Bayer 2-in-1 or 3-in-1 at least once a year, but I ignore the fert aspect as minor.

Aha! An admitted Bloom Booster in our midst

All jokes aside - do you notice a difference in the blooms when supplementing extra phosphorus?

 

[Forsoothe!]

I have my instructions. I feed, they grow, who knows?

 

[Mycin]

Having looked into this further, it seems that fertilizing with nitrogen when blooming is imminent may cause the plant to grow further vegetative growth at the expense of the flowers. So it seems like reducing nitrogen in relation to P/K may be helpful, not so much boosting the P to some obscene level. The rest of the growing season, fertilize w nitrogen as normal.

In nature, nitrogen is typically delivered via animal droppings that are quickly washed away. One paper proposed the idea of plants being "opportunistic nitrogen consumers" - taking it up and applying it to further growth whenever provided, regardless of the stage of the plant. Full disclosure: much of the research I reviewed was based on orchids, but I figured the general principles would be the same.