Question: We’ll be adding a new addition to our home in May and I wanted to move my bearded irises out of the way first. I know it’s best to transplant them from mid-August to mid-September, but that just won’t be possible. I thought I’d try to do so early this spring, when the new green shoots are still very short. I’m assuming this will pretty much ruin the flowers this year, but it’s that or abandon them.
Is it worth trying or should I just start over with newly purchased plants?
Answer: You should definitely move them and you’ll likely have great success doing so. Here’s why.
Each Plant Has a Transplanting Season
There is an ideal time to transplant any plant. For the bearded iris (Iris× germanica), also called German iris, that’s at the end of the summer. For most other perennials, shrubs and trees, it’s early spring, when the foliage is just starting to sprout, or in the fall, when the growing season is essentially over.
Normally, you should transplant plants at the season opposite to their flowering. That way, the plant will have the best chance of recovering fully before having to spend energy producing flowers.
For example, plants that bloom in spring, like tulips, narcissus and irises, are usually transplanted in the fall, while those that bloom in the fall, like asters and chrysanthemums, are usually transplanted in the spring. As for plants that bloom in summer, typically you can transplant indifferently early in the spring or in the fall.
When we transplant something at its most favorable time, it usually resumes flowering just when it always did, almost as if you had never moved it! That’s ideal … but there are other possibilities.
Moving a Plant in the Off Season
Special situations do come up and you may find yourself forced to consider transplanting or dividing a plant in what is technically the wrong season. Maybe you’re moving or you’ll be away or heavy equipment will soon wipe out the planting (as in Iris Gal’s case), but you just can’t transplant at the right season, but have to do it at another time of the year.
So, just do it!
When transplanting out of season, first suppress any flowers or buds. When you dig, take, if possible, take a larger root ball than usual and replant the plant to the same depth as before. Add some compost or all-purpose fertilizer to the soil (for plants that like rich soil) or maybe mycorrhizal fungi, but never starter fertilizer, also called transplant fertilizer (read The Myth of Starter Fertilizer to understand why). Water thoroughly to finish and, over the next 3 to 4 weeks, keep the soil a bit moister than normal to encourage root regrowth.
If the plant tries to flower right after planting, remove the buds and flowers. That way you’ll force the plant to “focus on proper rooting” rather than investing in flowering. Don’t let it flower until later, probably next year, when it is well rooted.
So, in your case, after you transplant your irises early this spring, make sure you remove any flowers they try to produce, but only this year. By next spring, you can let your irises bloom their little hearts out!
Transplant Any Time
You can basically transplant any plant in any season: at least, as long as the soil isn’t frozen! You just have to give a bit more TLC if the plant is in full growth or about to bloom.