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Club News – February 2020

Workshop – Help Your “Problem Child” Tree
February 15th @ 7PM

By Richard Phillips

Do you have a tree that’s a “problem child?” Stays up all night playing online games and looks droopy in the morning? Probably not but you might have a tree that you know you need to work on, but you’re not sure what to do. It might be a tree you’ve started, but now you’re stuck about what to do next. Or it might be something, such as a nursery stock plant, that you need initial styling help with. If so, the February meeting is the time when you can present your questions to your fellow club members for their insights and suggestions. And if you bring tools, wire, etc., you can get right to work while the ideas are fresh in your mind. And, even if you don’t have a tree to present for input, you will advance your knowledge as you observe how others approach the bonsai design decision process. From advanced bonsai artists to absolute beginners, we all run into situations where another pair, or a dozen pairs, of eyes, gets us to the solution we need for our tree. So, come to the meeting and find a solution for yourself or help someone else figure out what they need to take the next step. 

Monthly Tasks

Each month there are a number of tasks you need to do to your bonsai – from repotting, to fertilizing to spraying for pests. We have put together a checklist, customized for the San Francisco Bay Area to help you. This checklist is adapted from earlier work by Mitsuo Umehara. 

This month: February Tasks


January and February Potting Parties

By Lynne O’Dell

Thank you to Gordon Deeg for hosting our January potting party and to members who came out to enjoy Gordon’s garden, learn a bit more about repotting and styling and enjoy the camaraderie while working. Thank you for joining in: Gordon Deeg, Charlene Fischer, Barbara Shahinian, Mark O’Brien, Jim Faulkner, Michael Greenstein, Lynne O’Dell, Richard Murray, Richard and Barbara Phillips, Katherine Glassey, Rita Curbow, Idris Anderson, Donna Farmer, and Mitu Bhargava.

See you at our 3rd and final potting party on Sunday, February 24 from 10-4PM.


Soil Making Event “Thanks”

By Lynne O’Dell

A sincere thank you to our soil making team of Tom Romer, Charlene Fischer, Jim Faulkner, Armand Navabi, Lynne O’Dell and Andrew Lipson who put together 350 lbs of bonsai soil and took home 30 lbs. each for their own use. Our soil mix is one-third acadama, one-third garden pumice, one-third lava and a bit of fir bark.


January Meeting Recap

Ryan Nichols gave a very informative presentation on how to achieve optimal roots for our bonsai. Ryan has degrees in Horticulture and Biology respectively from Cal Poly Pomona and UC Riverside. Ryan has only been practicing the art of bonsai for ten years but got off to a fabulous start by entering the Joshua Roth competition in 2008 and winning First Place! Ryan started his presentation by discussing principles vs. practices.

Ryan discussing Root Conditions
Ryan discussing Root Conditions

Principle and Practice

Principles should never change. Practices change as we adapt to achieve desired principles. “How often you water during different parts of the year” is an example of a practice. “Your plants always need watering” is an example of a principle.

In order for your tree to grow, it will need water, air/oxygen, light and nutrients. To fully understand how a tree uses these resources, we need to understand how roots work.

Main Functions of Roots

The main functions of roots are to handle water uptake, nutrient uptake, enable gas exchange (mainly oxygen), provide structural stability for the tree and enable excess energy storage in the tree trunk, branches, etc.

Roots use oxygen and water to respire and give off carbon dioxide (same as humans) but trees store more carbon dioxide than they emit. That is why trees and other plant material are so critical for our planet.

Root Anatomy

Root hairs are where eighty percent (80%) of water and nutrients is taken up. When we repot we cut those off but new root hairs can regenerate over the next two days. Therefore, you would not fertilize directly after a repot because the fertilizer would stay in the soil and then pull water out of the tree. It’s okay to use bone meal during a repot because organic fertilizer requires a lot of microbial activity that takes time to build up after a repot. In other words, the organic fertilizer is not used until this happens.

After a repot, you don’t have to do a Foliar feed but you might want to do so in certain circumstances (e.g., the tree was losing color). Apply the Foliar feed on the bottom of the leaf because the stomata is on the under side of the leaf. The amount taken up on a Foliar feed differs based on the type of tree. Note that the stomata are located on both sides of the needles of pines and junipers.

The balance of water and oxygen in the roots is really important for healthy root development. Over-watering means there won’t be enough oxygen in the roots. Tilt the pot during rainy season for hydrostatic pressure to cause the water to drain. Plants will take up any water left after the gravitational free water is gone.

Foliage Reduction

If you repot at the most appropriate time for the given type of tree, then you don’t have to take off foliage. Junipers prefer more foliage to recover after a repot. They need more foliage mass to regenerate the roots. Pines are the opposite from junipers. So it is species specific. You can prune a pine back in the fall if its root system is healthy and then repot it in March.

Ryan discussing foliage
Ryan discussing foliage

Optimal Root Conditions

In nature plants grow where they can compete the best. In other words, they grow where they have the least competition.

In bonsai, we can improve our success rate by taking note of the optimal growing temperatures for different types of species.

Ryan discussed how a heat mat could be used to raise the temperature so the roots will start growing before the foliage starts growing. A heat mat could be used after a repot or at any time the root system isn’t growing vigorous enough and needs improving for the health of the tree.

During summer months bonsai pots can get too warm and black plastic nursery pots are often too hot for roots. Ryan wraps foil around the container in hotter months to lower the temperatures in pots. Other speakers have suggested other approaches, including draping shade cloth on top of the roots and pot. Or, even stretching shade cloth above the entire bonsai collection during the hottest days.

A temperature range of 60-90 degrees Fahrenheit is optimal for root growth. Within that range, cool climate species grow best in 60-75 degrees Fahrenheit. Warm climate species grow best in 70-85 degrees Fahrenheit.

Root Zone Heating

Gently warming the roots of new plants is a common technique used in production nurseries and greenhouses (search for Root Zone Heating). However, this technique isn’t widely used in bonsai. Ryan talked about how he uses it during cold weather or following repotting. 

  1. In a greenhouse plants often are at ground level, but a slightly higher level makes it easier to work with. Ryan builds his table at a height similar to other bonsai benches.
  2. Use concrete blocks to build a base – or whatever you normally use when building your benches. Top with a piece of plywood (bench base) that’s a few inches wider than the heat pad you have. Many pads are 12 to 16 inches wide, so a bench that’s 18 to 24 inches wide might be a good starting point.
  3. Build a wooden frame that’s a couple of inches larger than your heat pad using 1×3 or 1×4 boards. Simply nail the boards together at the corners. This frame will sit on top of the plywood base and will contain pumice that will surround the plants (later). It isn’t attached to the base with nails or screws. 
  4. Ryan places a sheet of Styrofoam house insulation (from Home Depot or Lowes) on top of the plywood. This will reduce heat loss thru the bottom of the bench. The Styrofoam should be cut to the same size as heating pad. 
  5. Most heat pads require that the bench be grounded. Ryan accomplishes this by placing a galvanized screen on top of the Styrofoam sheet. Using a ground wire, attach a thermostat to the galvanized screen (if you installed one).
  6. Temporarily lift the wooden frame and place a sheet of plastic on top of the Styrofoam sheet. This will keep the Styrofoam and plywood from getting wet. 6mil thick plastic should be good.
  7. Cover the plastic with a 2 to 3-inch layer of pumice. Without the pumice the pots will only be in contact with the heat mat thru the pot bottom. The pumice helps transfer heat to the sides of the pots and reduces heat loss due to air movement between the bonsai pots. 
  8. To use the heated bench, scoop a space in the pumice large enough to hold the pot you want to add. Leave an inch or so of pumice at the bottom and then place your pot. Now scoop pumice up to the sides of the pot. 
  9. After placing your trees in the pumice water everything lightly. When the pumice is damp it retains more heat and transfers it better to the pots. As you water your plants the excess will flow out the bottom of the wood frame. 
  10. You still need to check your tree to make sure it doesn’t dry out. It is not uncommon to have tree roots growing quicker than usual and requiring water sooner than you think if you have never used a heat mat before. Don’t let cool outdoor temps fool you into thinking that your recently repotted tree does not need water if you are using a heat mat properly.

If you a purchase mat make sure it is sturdy enough to tolerate the elements. Some are too flimsy for use outdoors. 

See Making a Heat Box for detailed instructions on how to build a box to keep tree roots warm. Also see the Member Story about a similar tool – Building a Temporary Greenhouse.

I know everyone will agree Ryan did a great job. Thanks Ryan!

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