Here are a few common questions regarding the growing and use of the
luffa sponge gourd.
How do I know when it is time to pick Luffa?
If being grown for food the fruits can be picked anytime until they start
to grow fiber. Edible size luffa has a thin tight skin. The flowers and
buds are sometimes eaten also. Once the the skin thickens and becomes
tougher they are beginning to develop into fiber. If luffa is very bitter
it may not be good to eat. If being grown for a fibrous loofah sponge, the
seed pods must be allowed to mature on the vine. When the cellulose fiber
of the loofah finishes developing, the skin loosens and often turns brown.
Loss of weight is a good indicator the sponge is ready as it loses water.
If the skin is a papery dry brown, the loofah is probably beyond ready.
It's often better to pick them earlier, as soon as the skin feels like it
will come off. The fibers tend to get darker and develop more dark spots
the longer they hang past maturity. If the vines get killed by frost or
freeze the pods should be peeled soon, even if they aren't fully mature.
They won't develop any more. They can be allowed to hang on the vine for a
few days but once any black areas appear they should be peeled immediately
before the whole thing rots.
Why has my Luffa vine produced many flowers
but no loofah?
The most likely cause is a lack of pollination. Bees and other pollinating
insects are needed to produce a good crop. Even with an abundance of
insects only a fraction of the flowers will pollinate. Bees are diverse
and abundant here in the southern Appalachians, yet we only have about a
30% rate of successful flower pollination. Bees are having survival issues
in some parts of the world. Insecticides used near the vines will reduce
the pollinating insects. Hand pollination is an option. Use a cotton swab
to move pollen or pull off a male flower and gently rub the yellow
hair-like structures of the male flower against the middle parts of a
female flower. Another possible cause is a lack of female or male flowers.
Typically a larger single female flower grows on it's own stalk while
clusters of male flowers bloom in sequence nearby on another stalk.
Normally the ratio of female to male flowers ensures a reasonable amount
of pollination. Some plants may not produce enough males or females. The
ratios of fertilizer elements in the soil can affect flower ratios for
luffa and other similar flowering plants. High nitrogen can increase the
number of males while high phosphorous may encourage more females. So if
you are lacking female flowers some additional phosphorous may help.
Why are my seeds slow to sprout?
Seed germination is equally dependent on moisture and temperature. If the
seeds are moist but not sprouting then it may be too cold. The soil needs
to be warm, near 70 degrees F (21 C) or warmer. For outdoor soil this
roughly coincides with the local frost free date in spring. If the seeds
have been stored in a hot dry place they may become hard. Hard seeds will
take longer to sprout and may not germinate at all. To speed up
germination of any seeds, wrap them in a wet towel in a warm place for a
day or two before planting. You want just enough water to keep the seeds
moist and humid but still allow air in. Even under ideal conditions some
stubborn luffa seeds may take a long time to germinate. Over three weeks
is not unusual. Normally it takes one to two weeks, sometimes less. We
tested seeds that had hardened from being stored in a warm place. They
took 24 days but most finally did germinate. Seeds planted in soil that is
too cold or wet often decay without sprouting.
Why did my Luffa plants not survive?
Too much water or cold can wipe out a healthy luffa plant. The full grown
vines are fairly tough and resilient. The smaller plants are not. The
roots won't survive muddy water saturated soil. A drop in temperature will
stop growth of luffa. A large vine may survive and grow if it warms up
again but a seedling can die. Frost is fatal to all luffa vines. A cloth
cover can save a vine from a light frost, but not a hard freeze. The small
plants are easily wiped out by pests like slugs. Weeds will overpower the
seedlings until they start to vine. Animals like deer have been known to
eat luffa. Salt or sodium in the soil or water will have a negative effect
on the plants. Most insects don't seem to like the taste of luffa leaves
but a few may attack and cause leaf curling. This may happen when parts of
a vegetable garden die off and hungry bugs move on to nearby green luffa
vines. In some cases insecticide may be needed. Whether using chemicals or
organic methods like insecticidal soap or neem oil, apply carefully and
avoid getting any on the flowers. Why are buds turning brown and falling
off? This is most likely a fungus. A brown circle forms at the base of a
flower bud where it meets the stem. Before long the entire bud turns brown
and falls off. This tends to be a larger problem in wet weather. Losing a
few buds in a normal year is common and not a big deal. A long wet growing
season can cause significant loss. Fungicides like those used for grape vines can help prevent further infection but won't reverse existing
brown damage. The best defense is a good arrangement and location of the vines. The vines should
be uncrowded so air can flow through. More sun exposure is better. Avoid
getting the leaves wet when watering. Giving the vines a good balance of
fertilizer elements to grow strong blooms will help too.
Why did the soap I made with Luffa fiber turn
If homemade luffa soap turned green inside it was from sap that remained
in the section of fiber that was used. It is always best to thoroughly
rinse any freshly picked loofahs as the fiber will contain a fairly large
amount of plant sap. Even a pod that is completely dry with brittle brown
skin still has some dried sap in the fibers. We use a hose to spray out
sap. It takes a long time spraying to get most of it out. If it is very
green, banging the loofah against a hard surface will knock more sap loose
and then it should be sprayed again. Washing in soapy water is another way
to get rid of sap. Squeeze and knead the loofah repeatedly and follow with
a good rinse. Drying in the sun helps to break down any chlorophyll left
behind. Most commercial loofah has been cleaned of all plant sap and won't
cause this problem but it still might be a good idea to wash it well
before using it in soap making.
What do I do with immature green pods if my
Luffa vines have died?
vines are some of the longest lived annual gourd type vines. In our area
most pods reach maturity but many vines often continue to grow and make
pods until hard frost wipes out the leaves. It's typical to end the season
with a few green immature luffa pods at different stages of development.
The smallest ones may be edible. The larger ones won't be. Some of them
may have good fiber and some won't. The first thing to do is figure out
what you have. Pulling them off the dead vines and slamming the pods
against a hard surface is the fastest way to find out. The outside will
crack. If enough fiber is present it will hold the pod together and may be
worth peeling. If it breaks or falls apart then it has not developed
enough fiber. It can be a lot of work to get hard skin off but sometimes
it gives good results. It may be a good idea to wear gloves if you have
many to peel. It only takes a few tough ones to heavily exfoliate your
hands. Simply slamming them on the ground without crushing is often enough
to break the skin loose. It may take much longer to peel hard green pods.
The seeds will likely be soft, white and not viable. The resulting sponges
are usually less rigid and softer but may still be useful. If slamming and
beating the pods doesn't sound like your idea of fun then freezing or
lightly baking the pods will soften the skin and allow it to slide off
more easily. It's still a good idea to first test the loofah pod by
hitting it before investing time and effort in it.