October 2020 - 28

CONTROLLED ENVIRONMENT AGRICULTURE
Figure 7. A tray with drainage holes and
grafted plants.
Figure 10. Trays of grafted plants post-healing.
GRAFTING PHASE
Pre-grafting/seedling
growth phase
Grafting phase
DAY
Day 1
Day 3
Post-grafting/healing
phase
Figure 8. A tray without drainage holes
with a small amount of water poured
into it.
Day 21
Day 25
Day 26
Day 27
Day 28
Day 42
Table 1. A typical grafting timeline.
and thus breaking the grafting union. By placing
the plants under a bench, a portion of the light is
filtered out so the healing plants get approximately
60 μmol·m-2
daily light integral of 3.5 mol·m-2
·s-1 for 16 hours/day leading to a
·d-1
. A shade
cloth could also be hung in the chamber to the
same effect.
After the plants have been kept under
Figure 9. Grafted plants in trays with humidity
domes and plastic wrap placed beneath a
bench (and raised off of the floor).
second tray, making sure the water does not
reach the bottom of the tray with plants. Next,
a clear, plastic humidity dome should be placed
over the trays and the dome and trays should be
wrapped in plastic wrap to prevent any humidity
from escaping. The sealed dome should then
be placed under a bench in the same growth
chamber where the seedlings were grown
(Figure 9).
It is important for the healing plants to have
some light, but if the light is too strong it can
heat up the leaf surface causing transpiration
28 OCTOBER 2020 GPNMAG.COM
these conditions for four days, it is time to
start acclimating the plants to the outside
environment. Four days after grafting, two
large lateral slits should be cut into the plastic
wrap where the dome and the trays meet to
start letting some of the humidity out. One day
later, the plastic wrap should be removed and
on the next day the humidity dome should be
cracked open slightly to continue to acclimate
the plants to the outside conditions. On the
seventh day after grafting, the humidity dome
can be removed and the plants can be moved
onto the benches to expose them to higher
light levels (Figure 10). The grafting clip will
most likely have fallen off by this point, but
if it hasn't it should be removed manually.
At this point, the plants should be acclimated
to the growth chamber conditions and can
now be transplanted into rockwool blocks
or larger pots. Two weeks later, the tomato
plants will be ready to be transplanted onto
rockwool slabs (or into other soilless media) and
brought into the greenhouse or high tunnel.
Tip #6: For larger-scale grafting projects, a
climate-controlled chamber with a fogging system
that can achieve nearly 100% humidity can be used
in place of the humidity domes.
Tip #7: The trays and humidity domes can be
reused multiple times; however, it is crucial to
thoroughly wash and sanitize them before reusing.
Although the grafting process can take some time
and effort to perfect, the team at Cornell reports 95
to 100% success when using these steps. In general,
growers can save a lot of money, greatly increase
the quality control, and learn a very useful skill by
grafting their own tomatoes.
Charles Gagne (cg597@cornell.edu) is a recent MPS
graduate, Masaki Kurosaki (mk2555@cornell.edu) is a
current M.S. student, Dylan Kovach (dck233@cornell.
edu) is a recent M.S. graduate, and Neil Mattson (nsm47@
cornell.edu) is an associate professor and Extension
specialist within the School of Integrative Plant Science at
Cornell University. Mattson directs Cornell's Controlled
Environment Agriculture program. Go to cea.cals.cornell.
edu for more information.
ACTION
Seed the scion cultivar
Seed the rootstock cultivar
Graft
Cut lateral slits into plastic wrap
Remove the plastic wrap
Crack the humidity dome open
Remove dome, place on bench
Transplant into rockwool block or pot
Transplant onto rockwool slab in greenhouse
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October 2020

Table of Contents for the Digital Edition of October 2020
