Hopefully all your bonsai trees were protected over the winter and you are starting to look forward to the onset of Spring in the UK so here is a quick generic guide to bonsai in March.
Continue to check your trees daily and water as required. Watch for buds swelling and ensure to keep trees topped up with water during this period especially for flowering trees who are coming into bloom. Water in the mornings ideally to avoid the colder temperatures at night. Spray any repotted trees to ensure they do not dry out.
You should now be in full swing of your re-potting as the onset of Spring is now upon us. So with your soils sifted, pots selected and wire to the ready let re-potting commence in full if your haven’t started already.
During repotting smell the soil that the tree comes out of, check roots for dead sections and rot ie look for black roots and remove any dead roots.
Check also for pests in the soil and roots and remove or treat any pest problems like vine weevil larvae and mites. Prune roots dependent on the stage of root development and ensure the correct pot size if changing the pot.
Ensure that the soil mix is suitable for the tree species and that you use a range of techniques that are suitable for the tree species, stage of root development and health of the tree.
For any trees that you are not repotting still remove the top surface and re-top dress to remove any crusting on the surface to improve airflow and drainage down through the soil. Plus clean the pots of the trees if they have got green algae forming on them.
For broadleaved trees, feeding should not be necessary yet as the leaves are still not out and do not feed until at least 6-8 weeks after repotting for all trees that have been newly repotted.
Tropical trees and Evergreens can continue to be fed with a low nitrogen feed to maintain health and vigour at the onset of spring.
Species to avoid pruning in Spring due to potential for sap bleeding would be Acer, Betula, Carpinus, Carya, Juglans, Magnolia, Morus, Populus and Tilia.
If you haven’t carried out your winter re-structure pruning if the buds have not started to fully swell then it would be alright to carry out any branch removals to address defects but ensure to cover with wound paste.
Remove and thin out unwanted buds or buds facing the wrong direction but do not over trim or prune at this stage.
Until the leaves appear trimming will not be required on broadleaved trees but continue to prune tropical trees to maintain their shape.
Where too much growth is expected and buds are well advanced, removal of unwanted future twigs may be anticipated by pinching out buds now. Where density is required of foliage, pinch or remove the terminal bud to promote side buds to develop. This is also a good opportunity to check buds to see if they are viable.
Species to avoid severe root pruning in Spring due to potential for sap bleeding would be Acer, Betula, Carpinus, Carya, Juglans, Magnolia, Morus, Populus and Tilia.
Insects and pests
Hopefully following winter treatments the pest and insects should not be a concern in March but check for scale, mealybug and red spider mite just in case on overwintering twigs in old bark wounds and treat as necessary.
Moss and weed control
Continue to keep this in check and treat or remove unwanted moss and remove any newly forming weeds.
Check wires and guys to ensure they are not cutting in and this is a good time to straighten out dis-used wire, which can be re-used for training wire.
Continue to protect from late frosts as it is still not very warm outside and ensure to harden off leaves before moving your trees out from a cold greenhouse.
Continue to update your bonsai records and photograph your trees to record their progress.
This is a good time to still collect trees from the wild (subject to permission) as broadleaved trees are still dormant generally and lifting trees can usually be carried out from October through to the end of March subject to avoiding frosts or frozen ground.
This is something everyone should do each time they use their tools but often it is not easy to do depending on how often you are using your tools. However, it is good practice to clean and sharpen your tools after use and this is a good time to go through your tool kits and clean them up before the start of the pruning season.
Subject to how you display your trees, if you are looking to bring your trees out later in Spring from their winter protection it is an ideal time to clean off your display areas or benches and disinfect them as well as re-treat with a wood preservative or relevant treatment for the material so they show your trees off once they are ready to come out.
Sow any seeds this month like Dwarf Quince, Cedar, Pine, Punica, Cypress, Sophora. Take softwood cuttings when buds are well on the move.