Poppies are probably my favorite annual to grow in my garden because they're dependable flowers, attract bees, and grow in poor soil. I've blogged about how I sow poppy seeds in the garden, but they're prolific self-seeders too. Poppy seeds remain for years in the ground and will sprout when the soil is turned over and they're exposed to sunlight. While I save poppy seeds from my garden, I let most fall to the ground and self-sow. The one downside of self-seeding poppies is that they'll germinate in clumps which grow weaker poppies, but I've found transplanting poppy seedlings into other areas of the garden to be pretty easy after some observation and experimentation.
I have to preface what I'm about to say by noting that poppies are notoriously difficult to transplant. Poppies, as you'll see below, have long taproots like carrots that do not take to be disturbed. That being said, if you find them in the garden early on you can safely transplant the seedlings into other areas where there's more space for them to grow or where you'll be able to enjoy the flowers.
The first step in poppy transplantation involves learning to identify the seedlings among all the other seedlings in your garden. Papaver somniferum (annual poppy) seedlings are rather easy to identify because the leaves look like little lettuce leaves. In the picture above the poppy seedling is in the center of the photograph and if you study the photo you'll see the leaves are different than all the leaves around it.
The second step involves remembering that the taproot is really long and you'll need to excavate down a few inches. I plunge the hand trowel into the soil as far as possible before lifting the poppy seedlings in an attempt to ensure that I've I have not disturbed the root. The bigger the core sample of soil around and below the seedling the better the odds are that your seedlings will survive the move.
When you're positioning the seedlings into their new spot slide the clump of soil into the ground as gentle as possible. After careful transplanting your poppy seedlings will benefit from a being watered.
Here is an example of a poppy that is a little "long in the tooth" for transplanting. This seedling already has four true leaves and the taproot is as long as the palm of my hand. There's a 50/50 chance that a seedling at this stage of growth will not survive transplanting because the root could be damaged in the process.
A poppy seedling at this stage of growth is an ideal candidate for transplanting. The first set of leaves have barely emerged and the root isn't too long.
When transplanting annual poppies in the garden success isn't guaranteed but with some trowel and error (HA, get it?) your percentages improve and you get a better crop of poppy blooms and seeds in the garden. The best time to do this is really early in the spring when the seedlings are still young and on days that call for rain. The extra humidity and moisture will help the seedlings endure the shock of being transplanted. If you want to transplant Papaver orientale, the perennial poppy, the best time to do that is in August when the plants are dormant. Perennial poppy clumps only need division every 4-5 years. Besides learning when to sow poppy seeds and when to harvest poppy seeds there's not much to learn about growing poppies. They grow in poor soil and like full sun and in my garden at least I've found them to be very drought tolerant.