Are you in "avid daylily collection mode" and do not always have a piece of ground ready for your new acquisitions? Or is it a little too early to plant in the ground in your area? Or did you end up with a few extra plants and don't know exactly where they will go?
Growing daylilies in pots may help you extend your season or give you that little bit of extra time to convince your significant other that you need to dig up yet another section of lawn for more daylily garden.
While it is challenging and risky to overwinter potted daylilies in our USDA hardiness zone 4 garden, I have had good success with growing new acquisitions in pots before planting them in the ground.
I have even set pods on containerized daylilies. I set the pod for my daylily 'Love and Dazzle' on a pot of 'Desperado Love' (with frozen pollen—but that is another story), and that pod parent still grows in my garden today. I remember when the summer turned excessively hot that year, I brought 'Desperado Love' into air-conditioned comfort inside my house. That probably saved those pods from aborting, which happens all too often as a result of a heat wave. I waited until I had harvested the pods before transferring the daylily into the garden.
H. 'Desperado Love' (top) is the pod parent of 'Love and Dazzle' (bottom)
In general, if a daylily arrives in poor condition, potting might help, but it will take probably take six to eight weeks to see results. Do not count on a plant recovering in just two to three weeks.
I once received a new daylily as a partial fan with a small piece of crown and a bit of root. The hybridizer was not selling this daylily at the time, but he parted with this starter fan as a gift for me, so I was quite thrilled to get a piece. I potted it up so I could give it extra care. It spent most of the summer in the pot before it really took off. I planted it in the ground at the end of that summer, and in a couple of years, it grew into a beautiful clump. It was 'Judy's Penthouse Double', which won the Georgia Doubles Award at our AHS National Convention in 2007.
I use a commercial variety of soilless extra coarse potting mix made with a blend of pine bark, peat moss, and soil conditioners. Last year, I used a bulk nursery blend delivered by dump truck from a local supplier. The specific brand doesn't seem to matter as long as the mix is fairly loose. I always add my own fertilizer. Potting mix does not keep well from year to year because some components break down, so fresh is best.
I size my pots according to plant size. I try to keep the pot fairly close to the root size. That way, the roots will fill the pot and produce strong growth. I have a collection of pots in the one-quart size and larger so I can choose accordingly. I never put a tiny plant in a large pot--it will sit there forever. I might even trim the roots slightly to avoid using a larger pot (such as when a plant has one or two really long roots and not much else).
I wet the mix before filling the pot, but just until it's somewhat moist, not sopping wet--it should still be a little loose. I usually do a bunch of plants at one time, so I dump the potting mix into a garden cart (the one-piece plastic type), add water to to the whole batch at once, and let it sit for several hours or overnight before using. You could also use a wheelbarrow for this step.
I dip the pot in the mix and fill it to the brim. It will settle a bit after the final watering. Try to avoid layers in the pot (especially a moist/dry layer), but keep the mix uniform throughout the pot.
Do not press on the mix to tamp it down. Keep it loose. If using time-release fertilizer, add as you plant.
When I plant, I use a planting tray to catch spills. I remove as much of the mix from the container as needed to make room for the plant. I make a hole with a trowel and just let the roots hang down. I add potting mix around the roots, gently working it in with my fingers.
Avoid planting the daylily too deep--you want to keep the crown close to the surface. In my experience, too high is better than too deep.
After you plant, tap and shake the pot on a hard surface to settle the mix instead of pressing on it.
Label the container! You can write on the outside of a DRY pot with a paint marker. This is the most secure method, especially if you have garden visitors. You can also create a garden marker and stick it in the pot so it is ready for the garden when the time comes. I often do both.
After potting, water gently but thoroughly to eliminate air pockets. Air pockets can mean death to roots.
After the final watering, the top of the potting mix in the pot should be about 3/4 inch to 1 inch from the top of the container. This allows good air circulation but keeps water from running over the sides of the pot. If the top of the potting soil is too deep in the pot, fungus can develop.
If I receive a plant with a lot of foliage, I usually cut it back. My general approach is to keep the length of foliage similar to the length of the roots. When a daylily is dug and divided, the daylily does better if it is not trying to support a lot of foliage while growing new roots at the same time.
Because you are planting in a soilless mix, you should use a balanced fertilizer. I add about 2 tablespoons of a pelleted 13-13-13 time release fertilizer per one-gallon pot. I prefer a time release fertilizer, but if you fertilize regularly, other types of fertilizer are just as good.
I mix in about half the fertilizer throughout the mix before adding the daylily, then I add the other half just under the surface of the top layer of mix. I stir it in with a chopstick or wooden garden stake.
Check the label to see how to handle your fertilizer. The fertilizer I use needs to be protected from sunlight, so I make sure the mix covers it. It is also activated by warm temps, so in cool weather, it doesn't do much. You can give early potted plants a boost with a liquid fertilizer. Once things warm up, I rely on the time release fertilizer and do not add any more.
Place the pots in full sun. Water every day—and twice a day if it's really hot. In a northern climate, you rarely need to worry about overwatering if the mix is coarse enough.
If you are growing your newly potted plants outdoors, pests should not be a problem. Indoor potted daylilies might have more pests, such as aphids. Keep them under control by giving them a hard spray of water periodically until you can move the plants outdoors.
During the growing season, remember to check for weeds. The ideal growing conditions you create for your newly potted daylilies are perfect for weeds, too! It is amazing how fast weeds—including trees—can grow in a pot!
When it is time to plant your potted daylily in the garden, loosen the roots thoroughly and spread them out all around the plant. Remove some of the potting mix so the daylily will settle well into your garden soil. You may even need to do a little root pruning, which does not hurt the daylily and will stimulate new root growth.
Your newly planted daylily may need a little extra water during the first couple weeks while it adjusts to its new home.
Plant it in time to give it at least six weeks before the first hard frost.
I have not had a problem with winter survival of daylilies grown this way.
Have fun with your potted daylilies!