I would add for beginners to read Hartmann & Kester’s Plant Propagation, Principals and Practice to obtain an in depth understanding of why there are several critical factors that determine success or failure. Also some research into compatibility to know when you need an interstem depending on what varieties you want to graft. And finally I offer several tips that can be useful, particularly if you want to get ahead of the season by preparing in advance.
- Create ways to achieve near optimal callousing temperatures of the graft union. If bench grafting potted rootstock, you can use dark callousing by covering the graft to prevent light on the scion over a 1-2 week period while keeping the grafted plant covered in a moist environment.
- If you have a greenhouse, use it to you advantage to graft earlier than you could achieve optimal temperatures in ambient conditions.
- If you need an interstem, you can graft the scion or chip buds to the interstem and dark callous indoors for 1-2 weeks in a moist container prior to performing an outdoor graft to the rootstock. Once ready store interstem scions in the refrigerator until ambient temperatures are adequate for the type of tree being grafted.
- Keep an annual record of when you plants naturally break bud. This and the optimal temperatures curve below will help you anticipate when to start spring outdoor grafting:
Callusing temperatures of Fruit and Nut trees
Posted on May 21, 2013 by qwertyqweryt61
Many people ask me what are optimum callusing temperatures to ensure a good percentage of viable grafts.
Nectarines/Peaches – 18-26 deg C. ( 64.4 to 78.8F)
Apricots/Cherries – 20 deg C. ( 68F)
Plums – 16 deg C. ( 60.8 F)
Apples/Pears – 13-18 deg C. ( 55.4 to 64.4F)
Walnuts – 27 deg C. (80.6 F)
Grapes – 21-24 deg C. ( 69.8 to 75.2 F).
Do not forget tissue damage for most temperate fruit will occur at temperatures over 30 deg C. (86 F)
Temperatures either side of the optimum will also work, but the percentage take will be reduced. See graph below for walnuts.
Callus graph
Callus formation is required at the graft, therefore temperatures are only needed at the graft. The rootstock and scion can be held at lower temperatures to avoid breaking the dormancy.