From: klier@cobra.uni.edu
Newsgroups: rec.gardens
Subject: Re: Don't forget to pinch!
Date: 9 Mar 95 19:42:13 -0600

> Kay Klier (klier@cobra.uni.edu) writes:
>>Just a reminder to all the folks starting seeds and cuttings this time 
>>of year:  regular "pinching" (removing the terminal bud)  makes
>>bushier plants.

Jeff Cook (Jeff.Cook@FtCollinsCO.NCR.COM) writes:
> How do I identify the terminal bud?  I'm raising seedlings for the
> first time this year, and I'm a newbie at this; I don't want to
> pinch off the wrong thing and kill my plants.  Does this technique
> work with all plants?

It works well for dicots, which are most of the flowering plants, and
most of the flowers and veggies.   Their terminal buds are out in
the open compared to the terminal buds of the monocots (grasses, lilies,
etc.)

[Dicotyledons are plant that have two seed-leaves. That are the very   ]
[first leaves that the plant develops after sprouting. Morning glories,]
[roses and daisies are in this huge category. Monocotyledons have only ]
[one seed-leaf. Tulips, grasses and irises are in this much smaller    ]
[category. So is corn (maize). They usually have strap-shaped leaves.  ]

(Challenge to the reader who has a good magnifying glass or access to
a dissecting microscope: Find the terminal bud (apical meristem) of a
corn plant.  Nope.  Look.  Lower than that!  Lower still! You're
getting warmer!  ;-) )

Back to the dicots: look at the stem of a plant, and notice how the
young leaves get progressively smaller as you go toward the tip of the
stem.  Look also at the point where the leaves join the stem, and
right above the place where the leaf joins, there will be a little
knot of tissue.  That's a lateral bud, or axillary bud if you prefer,
and it's got the potential to become a branch, a flower or an
inflorescence if it gets the right chemical signal from the rest of
the plant.  Mostly it just sits there and stays a bud, because the
terminal bud (apical bud) is producing a hormone, auxin, which keeps
the lateral bud dormant.

Go back to the tip of the stem.  See the leaves get progressively
smaller and closer together?  At the very tip, the smallest leaves are
curled over the stem tip, protecting some actively dividing cells
called the apical meristem.  The apical meristem and the young leaves
around it make up the terminal bud.  The apical meristem keeps
cranking out new leaves for its stem, and auxin that keeps the lateral
(axillary) buds from developing.

If you remove that terminal bud (traditionally done with nail of
thumb and forefinger, hence "pinching"), the supply of auxin
is stopped.  The next 2-3 axillary buds below the place where the
terminal bud was removed will start developing, usually becoming
branches, and making the plant much "fuller" and "bushier"
("Thriftier" in garden parlance).

When you pinch, you need remove only the terminal buds (and obviously,
the young leaves surrounding them if you don't want this to be a
high-precision surgical operation!).  Some people tend to overdo it,
and, with an unbranched seedling 4" tall, take off 2" of stem and
young growth!  That's kinda radical, and it tends to set the seedling
back more than needs be.  If you're careful, only a careful observer
will be able to tell you've just pinched a flat of seedlings.  If it
looks like you took the kitchen shears to the plants, you've probably
overdone it...

Kay Klier   klier@cobra.uni.edu
(whose mother used to go in the house and cry when her father
decided to prune trees.. rather brutally... in an attempt to
make them branch!)