bullhorn acacia lost a lot of leaves due to my learning curve of watering it in the fall with fluctuating temps

[rhawes]

anyone know how long it will take for leaves to grow back have not seen any new growth but what little it has it has kept. Should I trim it would that stimulate growth? anyone have any ideas?

 

[sorce]

May not be your fault.

I'd research their Natural seasons and see how to utilize that information in your quest.

Sorce

 

[Leo in N E Illinois]

Bullhorn Acacia is Acacia collinsii, on the Wiegert's website, and its current revised name is Vachellia collinsii. It is native to southern Central America. This area has an irregular dry monsoon climate, in that the dry and rainy periods are not as distinct as some monsoon climates. Where it comes from there is no winter or summer per se. There is the dry season and the wet season and the 2 seasons that are between the wet and dry season. Dry season for southern Central America is roughly Dec through April. Then the rain becomes more frequent. During the dry season it is perfectly normal to drop leaves. Because the sky is clear at night during the dry season, nights are cooler during the dry season than any other time of year. If you let your acacia get cold at night in Pennsylvania autumn, the Acacia probably thinks the dry season is here, and started dropping leaves.

Depending on temperature, your acacia thinks it is "dry season" or "dormant season". Keep it warm and moist and it will begin growing again. Or you can just follow what the tree does, keep it somewhat dry when it is not putting out new growth, then when you see new buds, new leaves coming, increase the frequency at which you water it.

 

[Mycin]

Bit of a tangent, but would it be advised to alter feeding regiment in a case like this? On the one hand, I could see it needing more nutrients than normal to regrow the leaves. On the other, I could see the case for reducing fertilizer on the grounds that it's a recovering tree.

Any thoughts?

 

[Leo in N E Illinois]

Bit of a tangent, but would it be advised to alter feeding regiment in a case like this? On the one hand, I could see it needing more nutrients than normal to regrow the leaves. On the other, I could see the case for reducing fertilizer on the grounds that it's a recovering tree.

Any thoughts?

Nutrients are used in proportion to rate of metabolism. A leafless tree has a relatively low metabolic rate. The trunk and roots of a leafless tree store a modest amount of carbohydrates and N-P-K type nutrients, enough so that adding fertilizer at this time is not critical. When leaves are expanding is when nutrients are being utilized rapidly. This is when chlorosis can show up, indicating insufficient nitrogen. But usually, if you see the new buds and unfolding leaves are a "normal" bright, new green to dark green, the tree has sufficient nutrient reserves. At one time it was thought that applying nitrate containing fertilizers to freshly transplanted trees was harmful to new root formation. Turns out this is not proven with any data.

So the result of my somewhat disconnected ramblings above. A consistent fertilizer program is better than anything else. Normally in winter, and dormant periods (periods where trees have dropped leaves and are semi-dormant) fertilizer is withheld or applied at a rate that is significantly less than the normal growing season dose. For example if your normal growing season dose of water soluble MSU fertilizer 1 teaspoon per gallon, applied every 2 weeks, in winter or on semi-dormant houseplants, the dose for leafless trees might be 1/4 or even 1/8 teaspoon per gallon every 2 to every 4 weeks.

Also remember, as a tree develops from pre-bonsai to bonsai approaching exhibition quality you are going to want to keep internodes short. Timing your fertilizer applications is a helpful way to do so. For example with single flush pines, fertilizer is applied ONLY late summer & early autumn, during the time period that the new buds for the subsequent year's growth are formed. At this time nice healthy buds form, autumn root growth will be healthy. Then no fertilizer late autumn through winter and NO fertilizer in spring. Buds sprout in spring, and grow using stored nutrients. Needles expand, but because nutrients are not in excess, they do not get overly long. Internode lengths are not overly long because nutrients from the previous autumn are being exhausted. New growth hardens off about middle of summer. Nutrients applied after growth has hardened off will not trigger growth. So begin fertilizing late summer and early autumn, again this will go into next year's buds rather than into current needle length and or current internodes.

SO you have competing goals, fertilize for vigorous growth, or withhold fertilizer to get shorter internodes, and more compact growth. WIth pines and very strictly seasonal trees like beech, the autumn fertilizer program is useful for manipulation of leaf and internode size. For other species, that grow more continuously, you want to feed them consistently, but at a light enough dose rate that you do not get overly vigorous growth. Feeding should be light enough that leaves are uniform and modest in size and internodes are nice and compact.

 

[rhawes]

My bullhorn grew back leaves Thank God!!!! Looking good will show a pic when I have time!!
Thanks for the input everybody!!! Merry Christmas!!!!