Pollination tips and techniques.

Last updated 10/25/07.

Daylily pollination is generally trivial in practice. You grab a stamen and brush some pollen from the anther onto the stigma of the pistil. Roughly six weeks later, there's a pod of ripe seeds if all has gone well. But there are some good reasons to know more and do more, because sometimes our efforts fail.

When a pollen grain lands on a receptive stigma, it rapidly germinates and grows a pollen tube all the way down to the ovary at the base of the flower. Nuclei travel down the tube and fertilize a single ovule per pollen grain. That ovule will develop into a single seed. This growth and fertilization happens very rapidly, in just a few hours. If you have pollinated in the morning, you can safely deadhead in the evening by cutting off the petals above the ovary.

Pollen is ready to use whenever the anther has split open and the pollen has dried and become light and fluffy. This doesn't usually occur during rainstorms or dew or mist, but it can happen at any time of the day or night, depending on the variety. On a few varieties that take days to fully open, such as POLAR PICTURE, it will occur a day before the flower is open. I often will cut a bloom that will open the next day, put it in water, and gather pollen when it opens. That's a handy trick for rainy days or when travelling to other gardens.

Collecting pollen is very useful. There will be days when your pod parent is open, but your pollen parent isn't: if you have stored pollen, you're prepared. I store pollen a full year so that I can put any pollen onto my extra early daylilies. I also exchange pollen by mail with other hybridizers.

Collecting pollen is easier than you might think. The trick is to keep the pollen cool and dry. At room temperature, the pollen keeps a week. In a refrigerator, it keeps for weeks, and in a freezer for years. My favorite method is simply to drop the whole anthers into a gelatin capsule (size 0 or 00) and write the variety name onto the gelcap with a Sharpie permanent marker. I close the gelcap, shake it so that pollen adheres to the walls, then open the capsule to dab stigmas against the visible pollen. You don't need gelcaps: you can go low-tech with paper envelopes, or high-tech with disposable plastic centrifuge tubes. I like the gelcaps because they are cheap, small, and absorb moisture. However, in excessively humid conditions, they will melt in your hands. I can usually make at least thirty pollinations with one capsule. I keep a bowl of recently gathered pollen in the refrigerator, and archive it in a jar in the freezer as I gather more.

Pod parents are ready for pollination when the stigma has become receptive. The stigma usually has three small lobes that start off pressed together. These then split apart slightly to reveal the receptive surfaces The stigmatic fluid that moistens these surfaces is essential to pollen germination, though you may not need a visible quantity. Many varieties of daylily are ready for pollination some time before the flower has opened: usually, the stigma has protruded from the bud and obviously become receptive. Go ahead and pollinate as soon as the bloom is ready. Some varieties also remain receptive well into the senescence of the flower, and can be pollinated even after the bloom has closed.

When I pollinate, I also label the pollinated bloom. There are lots of ways to do this, and what works for me is cheap paper tags on strings. I write on them with a Micron Pigma permanent pen. These have never failed me yet though they are fragile when wet. Some people get big storms that would destroy these, and use plastic tags, like the closures for bread bags. Others use color-coded wires. And some people tag entire scapes or entire clumps for single crosses. Any system will do: the goal is to know the pollen parent when you harvest the pod. Memory will not suffice. Choose the system that you find easiest to use, because tagging is usually slow and tedious.

There are many problems that can arise in pollination. The first is insect interference, especially pollen theft by earwigs and bees. Some mornings I'd wake up, and none of the nocturnals had pollen left because the earwigs ate it. I've solved that problem two ways: by collecting pollen in the evening and by eliminating the earwigs. In the mornings, I also race against the bees to gather pollen. They generally show up at around 8AM, which gives me plenty of time to get what I want for the day. Bees might also pollinate the blooms with the wrong pollen: such bee pods are not a big problem in my yard. But the solution is simply to pollinate before the bees do. The pollen tubes grow that fast that they should only need an hour's head start. Some folks have reported that ants damage the base of their pistil. That's an uncommon problem, and probably could be resolved with a little ring of vaseline around the scape as a barrier. Pete Wetzel suggests stuffing a few stamens into the tube so that the ants can't get down to the nectar.

High heat is a notorious cause of failure to set seed. It's not much of a problem in the north, but in the south it is generally solved with winter breeding in greenhouses and shade for plants grown outdoors.

Other problems revolve around difficult parents or errors:

There are some tricky pollinations with converted parents and parents that have unreduced gametes. Attempted conversions may be partial or may not succeed: if they have failed and the pollen is still diploid, pollination of tetraploids will not work. A few diploid (2N) varieties supposedly produce some pollen that is diploid (2N) instead of haploid (1N). These are called unreduced gametes. Tetraploids (4N) expect 2N pollen, and will accept this unreduced pollen. The ploidy of these pollens can be checked with a microscope.

In situations where pollination is iffy, and you really want to be sure that ONLY the pollen you put on could be fertilizing the blooms (such as when using converted or unreduced pollen), keeping bees away from the stigmas can be a nuisance. Screening works, but a simple small-scale solution is to put caps on the pistils. I break a round toothpick, and then roll a small rectangle of aluminum foil around it to make a tiny cylinder. I pinch one end shut, slide it off the toothpick, and then just slide it onto the tip of the pistil. Pistil caps are easy to make in quantity ahead of time. I've used this method to test for the presence of unreduced gametes. (So far, only negative results.)

When pollination fails, you will usually know promptly. Usually, the swelling of a pod becomes visible in two to four days or else the whole bud drops off. But sometimes you get air pods, pods that contain no seeds. Or pods that contain only seed coats. Those pods might appear normal until harvest.

But despite these challenges, most pollination is easy. Carry some stamens tucked in your lips and blooms behind your ears like the Stamiles, and give it a try!

Counter image omitted.

Copyright 2007 by Mike Huben ( mhuben@world.std.com ).
This document may be freely distributed for non-commercial purposes if it is reproduced in its textual entirety, with this notice intact.