Grow roots faster

Can I put a very diluted dose of fertilizer in my air layer material to get the roots to grow faster? If not, is there a some what inexpensive way to do this? I would just like to get them separated before winter.

I don't have any science to back this up, but my gut feeling is if there is fertilizer in the soil the roots might actually grow slower. To anthropomorphize a little bit, if small roots find all that they need, then they have no motivation to grow longer and seek out stuff elsewhere. It's been a long time since high-school biology, so I don't really remember exactly what the factors that stimulate root growth are, but I imagine that could be googled, if you were curious.

- bob

Well I was thinking about the first number of fertilizer encouraging root growth but you make a good point.

The general recommendation from plant propagation texts is that no fertilizer should be applied. Tests showed that nitrates inhibit the formation of roots. Nitrates actually inhibit the initiation of the root buds, once the root buds have started to grow out as roots, the effect no longer holds. So no fertilizer until after there is evidence the new roots are growing, then fertilizer is good.

I never fertilize my cuttings until after they start sending out new growth (a sign roots have already begun growing)

Jake16 wrote:Can I put a very diluted dose of fertilizer in my air layer material to get the roots to grow faster? If not, is there a some what inexpensive way to do this? I would just like to get them separated before winter.

The tree lives and grows on the food produced by its foliage. Therefore, the roots of your air layer can grow no faster than the foliage above the girdle can feed them. Further, as long as your layer is on the mother plant, the nutriments and water for the foliage come primarily (if not exclusively) from the mother-plant's roots.

Temperature certainly has an effect, with the highest growth rate occurring when the root temperature is about 70F to 80F (no root growth will occur when the root temperature is below 40F or above 95F). Anything you can do to keep the air layer temperature in this range will maximize the root growth rate. If your temperatures are higher during the day, say, covering the layer with aluminum foil would preclude solar heating boosting the air-layer's temperature. Conversely, exposing the clear plastic covering the layer to direct sunlight will boost the temperature - so too would a sheet of black plastic covering the works. You could stick a meat thermometer into your layer to see what the temperatures really are inside.

You could carefully part the sphagnum and dust the callus with more rooting hormone to add to the stimulus for adventitious cells to become roots instead of shoots. This always carries a risk of breaking off what roots your layer has generated, but is probably worth doing if you don't see any indication of roots otherwise.

Finally, if you get anxious and harvest the layer before it has generated enough roots, you get a dead stick. As long as it remains on the mother tree, it gets water and nutriments from the mother tree's roots. Foliage will reappear next season and you'll get another chance for that layer to succeed.

Thanks every one for the replies, one of my air layers has a decent amount of roots the other two have roots about 1/4 of an in. long I doing have a big problem with waiting untill next year to separate I was just worried about winter care

Don't mess with Ma Nature (at least in this procedure). Assuming you used a rooting hormone, that's all you need to promote the growth of roots. ANY messing with the moss or soil (depending on how you did it) will only disturb -- tear -- the very fragile new roots.

Being in a hurry is a VERY bad idea in bonsai. It almost always leads to trouble, if not outright disaster.

Jake16 wrote:Thanks every one for the replies, one of my air layers has a decent amount of roots the other two have roots about 1/4 of an in. long I doing have a big problem with waiting untill next year to separate I was just worried about winter care

We are heading towards milder weather...those roots will surely grow a lot more before fall/winter comes. Be patient and you might have enough to sever the air layer before winter. For now, just make sure the temperature is kept within the optimal range as Osoyoung described.

Poink88 wrote:
We are heading towards milder weather...those roots will surely grow a lot more before fall/winter comes.

Thats exactly what I was thinking. Its been really hot here in VA so I am assuming that fall will also be warmer allowing the roots to grow a good amount before winter.