“I have about 150 bonsais growing in my back yard.” – Cindie Duke Bonomi

Tree Calendar: Seasonal Tips – Spring


  • What your trees need from you this spring:
  • Clean tools with WD40, which removes sap and lubricates moving parts. Clean pots before you place trees in them.
  • Deciduous trees can be re-potted when the leaf buds start to swell and extend. It’s a short time frame, so if the buds start to open into leaves, it’s too late. Place wire screens over the holes in the bottom of the pot and wire in place, so the soil doesn’t fall out when watering. Wire the tree firmly in the pot through the bottom holes to make sure the tree doesn’t move in the wind and break the newly forming roots.
  • Conifers can be repotted when the buds start to move and white tips are showing on the root ends, usually after deciduous trees.
  • If root pruning, cut off longer tap roots and enough outer roots so that the tree fits in the pot with room to grow. Cut back any dead areas. Any larger roots can be cut over the course of several years, with the idea developing a network of small, hair-like feeder roots.
  • Use a course soil mix of Hadite or pumice and dried pine bark pieces (all materials screened to remove fine particles). A mix of 3-4 parts Hadite to 1 part bark is good for conifers, half and half for deciduous, and more than half bark for tropicals.  For very small pots and fine root development, a smaller particle will allow roots to grow and hold in a bit more moisture. Use a chopstick to gently poke in the soil and remove any air pockets.
  • If you are wiring any branches, do so before repotting when the tree is more stable in existing pot.
  • After repotting, soak tree in a shallow pan of water for 20 minutes and place in a protected, shady site on the ground for a few weeks to recover. Don’t over water since the plant is not taking up much water on its own.
  • Fertilize after a month or so when the tree has adjusted to the new pot.


4 Stages of Budding

1. Dormant bud stage – When the buds are tight on the branch, trees can be collected from the wild or lifted from the pot. Do not root prune or you will be cutting away stored energy.
2. Swelling buds – Coming out of dormancy, it’s o.k. to repot or root prune.
3. Extending buds – Best time to repot and root prune, a short time frame.
4. Open buds – Usually at the top or on branch ends, it’s too late to prune or repot.

What your trees need from you this Summer:

During the growing season, your trees need proper watering, fertilizing and pest/disease control.

WATERING:  It is better to water in the morning especially if you will be gone for most of the day. By watering the trees at night and wetting the leaves, you are making the trees more susceptible to fungal diseases. If your trees are not root bound and the soil is very free draining, you should water until it comes out of the bottom of the pot. Use a gentle shower setting and try not to wash away the top layer of soil. If the pot is easy to lift, a good five to ten minute soaking in a shallow pan of water will ensure the water has reached the bottom of the pot.  On very hot and sunny days, you may need to water several times depending on the size. If you are going on vacation, either take your trees with you (my wife won’t let me), or find someone VERY reliable to take care of them. If you can, move them to a semi-shaded area on the ground where the animals won’t get to them. Show your caretaker exactly how to water the trees, especially if you are going away for a long period of time during very hot weather.

FERTILIZING:   Your bonsai is in a confined space with little nutrients so fertilizing is a must.  A liquid mix is easy to use, like Peter’s and Miracle Grow. Miracid for acid loving plants like azaleas and conifers works well also. Some people use a solid product like Osmocote, which fertilizes the tree  every time it is watered. A good organic choice is Bio Gold Fertilizer, a triangular shaped pellet which sits on the surface of the soil.

A balanced 10-10-10 fertilizer is a good choice for most of the growing season. The first number represents the amount of nitrogen, which benefits the leaves.
The second number is the amount of phosphorus, benefiting the roots. Potassium is the last number, helping the flowers and fruit. A higher nitrogen fertilizer,
25-15-15 will help the leaves in spring, while a higher phosphorus fertilizer is beneficial in autumn for strong root development for the coming year.

The tree should be well watered before applying liquid fertilizer, or you run the risk of burning the roots. The amount and frequency of application is widely discussed,
as some people use half of the label’s recommended strength every two weeks while other use full strength. The amount of fertilizer may depend
on what you are doing with the tree. Too much fertilizer may cause excessive growth which may not be the desired effect on refined trees. If the tree is in training and you
want to thicken up the trunk and branches, you may feed with a higher dose. Cutting  back on fertilizer for pines in the early summer will shorten the needles on a finished tree.

DISEASE AND PEST CONTROL   An effective spray for both disease and pests would be a spray designed for rose care. It is mild enough to take care of
most problems you might find on bonsai. If possible, apply any controls on cloudy days or when the trees are shaded.  A strong spray of water will knock off aphids and any other insects that you can see.

PLACEMENT IN THE SUN:  Most bonsai do best in full sun. Some exceptions are Japanese maples, larches, hemlocks and rhododendrons. They prefer morning sun and afternoon filtered shade.  You may notice the leaf tips burned if they sit in full sun.  Be aware of what the bonsai pot sits on, as some dark surfaces will heat up more than light colored ones.  A bonsai sitting on concrete will have more heat around it than one sitting on a wooden bench or display stand.


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