Heat and Grafting

I have made a lot of grafts this season but I have a few Che and persimmon grafts left to make. The Che rootstocks (Osage orange) are prime for grafting but the persimmons are just now breaking bud, except for two persimmons which I grafted earlier this week.

The problem is that we’re about to have a 4-5 day heat wave. It will reach 90F tomorrow, 96 the next day, followed by two more days in the low 90s and gradually moving back down into the 80s.

Should I hold off on grafting until this heat wave has passed or will the grafts be ok if I protect them? Also, should I shade the grafts I made earlier this week?

I would say yes to both of you have the time and inclination to wait/install shade cloth

I seem to have better luck with persimmons when ambient highs are consistently above 70F and the leaves are about 1-2” long. If you wait a bit you may be in prime time for callousing to occur. In the 90s the scion buds are more likely to break out and wilt, before you graft union can heal enough for nutrients to flow to keep the scion hydrated and fed for growth to continue. You scions have a limited amount of energy stored, so you do not want them expending energy at a high rate during a heat spell. Given that you might expect more fluctuations in heat even if you wait, it’s a good idea to use aluminum foil to shield your grafts from mid day sun, allowing only indirect light for the first two weeks. Once you see growth emerging, and you are certain the grafts are taking, then remove the foil enough to allow several hours of morning sun. Then once you temperatures moderate and hold stream the foil can be removed. I often have the same issue here. A month ago we had 70F highs, but now we struggle to get high 50s. I’m still waiting to get into the 70s to do my persimmon, peaches, and pawpaws.
Kent, wa

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