Fertilizer Initiation in Spring

[miker]

I understand the conventional wisdom for temperate deciduous bonsai is to withhold fertilizer until 2-8 weeks after a tree leafs out in spring. Does this only apply to newly repotted trees and/or to established specimen bonsai to prevent damage to roots and control growth respectively?

Is there any harm in beginning to moderately fertilize trees that have not just been repotted right about the time the first green appears on the buds or at least once the tree is really leafing out?

 

[Guy Vitale]

You want to withhold fertilizer on established bonsai so the new growth isn't too strong. After the growth hardens off you can start fertilizing, there are spices specific recommendations like JBP you'll want to read up about though. I hold off fertilizing newly transplanted trees for a couple weeks, though some say that's not necessary. Trees in development start getting fertilizer as soon as they start to wake up.

 

[MichaelS]

If the tree has not been repotted you should begin light fertilizing early spring. (liquid is best until the weather warms up). This particularly goes for trees in development - which lets face it, is 95% of them. In this case you want the strongest growth possible and as soon as possible for as long as possible. That means feeding as soon as the tree is receptive. Let the tree be the judge when that is. If it is leafing out, it can take fertilizer. If the tree has been repotted, there is no need to hurry to feed as there is quite a bit in fresh soil and you should wait for the roots to take hold first anyway. If the tree is over 100 years then it still should be fed at the same time only more lightly and with possibly a lower N to P/K ratio. Most people way under-fertilize their trees in development. Use the scissors to control growth on them, not withholding of fertilizer.

 

[M. Frary]

Is there any harm in beginning to moderately fertilize trees that have not just been repotted right about the time the first green appears on the buds or at least once the tree is really leafing out

I fertilize them at next time I fertilize them. If fertilizing day is the next day after repotting then I fertilize them. With my normal fertilizing mixture.

 

[Eric Group]

I don't really stop fertilizing. We have such a short dormant period, I may cut back or stop around December, but this year, we were getting up into the 60-70 range in January and stuff has been waking up in February... so I was fertilizing again as early as January... that isn't really much of a break!

Typically I use mostly slow release organic fertilizer... with this, I want to have it added to the tree before it grows. You want strong vigorous growth in the Spring right? Tree can't do that without food... obviously on an ancient, establish bonsai of a variety prone to grow fast and mess up your design, you might do something different... withhold the ferts a little more... but with the vast majority of the trees I see people posting here, they are (or at least SHOULD BE) still in some form of development... don't worry so much about withholding food! Worry more about GIVING THEM LOTS OF IT! Too little feed, and too little water are the biggest issues I see affecting trees negatively among those new to Bonsai. (Why is my tree dying, why is Pine turning yellow, what is wrong with....) They read all this stuff about timing fertilizer and how to avoid "root rot" and think they should stick their "sticks" into a coarse bonsai mix, never water them and feed sparingly, then they wonder why the tree dies! Water a bunch, feed a bunch, error on the side of MORE with both and your trees will be happier for it.
*Obviously massive amounts of chemical ferts can be damaging though, so mix it up with what you feed and I strongly recommend using mostly organic... if you do use chemicals, especially liquid- stick to recommended dosages and don't feed as often. The salts can build up in the soil and cause major issues...

 

[Guy Vitale]

Water a bunch, feed a bunch, error on the side of MORE with both and your trees will be happier for it.

Could not agree more, I would preface make sure you use a course mostly inorganic mix.

I use tea bags filled with fertilizer organic mostly and I water weekly using a liquid seaweed and balance Jacks or miracle grow. I was guilty of under fertilizing, once I got on my new regiment, my trees are thriving which allows me to incorporate better Bonsai practices.

 

[quietobserver]

http://walter-pall-bonsai.blogspot.com/2009/06/feeding-again.html?m=1

I use the Walter Pall method. Early, often, and heavily. Since I've 'switched' a few years back the improvements have been significant for me.

 

[Paradox]

It really is species dependant and stage of development dependant. Also depends on your local climate.

Most Pines (JBP, JRP) and junipers start feeding early-March in normal years because that's when the roots start waking up here. I'm going to start this weekend this year for the ones I have in the garage. Will wait a bit for the ones in the cold frame which are cooler.
You want strong growth on pines early. For 2 flush pines where you'll be cutting candles, feed heavy until you cut the candles in July. Then hold off until the new candles open and harden off. You want slower growth on the second flush to keep smaller internodes and tighter branching.

Junipers: feed. You want strong growth at this point and will cut back later.


Rumors are March is going to get cold again so be careful of putting trees outside yet.

For maple and most deciduous, conventional wisdom is to hold off until the first flush of leaves is hardened off, especially on trees that are undergoing branch ramification and trunk size is already accomplished.

Again the goal is smaller internodes. You've also got to stay of top of pinching or the tree will get away from you and your internodes will be too long. If you feed heavily you better be on it every day. Most of us with jobs have a hard time doing that. People that are growing bonsai full time or have a team of apprentices full time can do that.

You're not starving the tree, it has reserves from the previous year to make new growth as long as you fed it after the first growth last year. You are controlling growth to produce tight foliage.

If you are trying to grow a trunk still then feed.

 

[jeremy_norbury]

I believe this is advice based on old soil compositions.

Old school soil often consisted of significant amounts of potting compost - which already contains fertiliser/nutrients.

It therefore made sense that immediately after repotting you would not need to apply even more fertiliser.