Lilies and Related Plants - RHS Lily Group

Figure 2. Lilium philadelphicum × Lilium catesbaei in jars of culture medium.
losses. Consequently, the in vitro approach seemed to be the way to go and most
all of the hybrid seed went directly into tissue culture. I kept the plants in vitro for
as long as possible with material moved to fresh culture medium about every 4 to
6 months. After 18 months (February of 2011) a few bulbs put up stems in the jars
and everything had to come out of culture. Well, almost everything. It is difficult
to get these fragile tangles of bulbs out of jars without breaking off scales or even
shattering bulbs. Those left over bits and pieces went back into tissue culture.
Cultural requirements
I have not had these hybrids that long, so I cannot make definitive statements about
cultural requirements. A few of the F1 plants flowered this year and most should
flower for the first time next year. The bulk of my material is growing in pots and
will be kept inside over the winter. These do not get any special care. I have been
using a light garden soil in the pots (which I use for most lily seedlings) and the
plants are doing well in pots and have been quite easy to grow. So far there have
been no problems. This is surprising as most lilies, including L . philadelphicum,
eventually get over watered and start to rot when I grow in pots. I speculate these
have inherited a resistance to bulb rot from L . catesbaei.
About 25 seedlings were planted into my garden this July to test cold hardiness
and garden worthiness. So far the plants are still growing in the garden but this
winter will be the real test. I also shared about 100 of the tissue culture plants and
vernalized bulbs with perhaps a dozen individuals who will evaluate these hybrids
in their own gardens. Others grew these from seed. Everyone has different
growing conditions and different ideas for growing these. It will take a year or two
for most of this material to become flowering size plants. At some point I hope we
can all compare notes.
So far I understand that one person managed to flower one of the seedlings.
The lily came out of tissue culture as a small plant in 2010 and flowered in 2011. It
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