Can I transplant young Rose of Sharon plants in July in Zone 6a?

Question

I live in Massachusetts, growing zone 6a. Yesterday my husband was given some young Rose of Sharon plants from a friend at work, grown from seed by someone else. I've always wanted some, and would like to know how best to ensure successful growth. There are six seedlings, ranging in height from 7" to 12", in a 9" by 9" plastic pot filled with dense wet soil, which looks to me like garden dirt.

Can I transplant them now? I've been told this is the worst time of year to do that. Our temperatures are between eighty and ninety degrees F during the day, sometimes hotter, down to the sixties at night, and it's quite humid.

How should I care for them while they're in the pot? As you can see, the stems are bending. Is staking a good idea, or would that disturb the roots? Should the pot be in the sun or shade, and what's the proper amount of water? If it's too soon for planting in the ground, do they need separate containers, or are they okay together?

Finally, how much distance will they need between them, or other plants, in their permanent spot? I have a section of day lilies, some of which I'm planning to remove to make a home for the Rose of Sharon.

Edit to provide requested information: The variety is Hibiscus syriacus. The parent plant is full and bushy, with single purple flowers. It's six years old and just over six feet tall.

click on pictures for full size

Answer 1

IMPE, Rose of Sharon is a fine, hardy weed with pretty flowers. As such, good time or bad, it will probably survive transplanting. I see little effective difference in transplanting from a pot to a pot and transplanting from a pot to the ground, if you stay on top of the watering. Providing some shade cloth for a few weeks probably would help at this time of year.

All of mine were weeded out of a friend's backyard, transported bare-root with damp paper and plastic wraps, and planted without special care, other than choosing spots that reflected the tendency to become a weed. All survived that, and most have survived long-term.

Depending on light and soil, up to 8 feet may easily be consumed by one vigorous plant. If you prune them, you can influence how much they are "small trees" (trim side branches up to a "crown" level, trim to single stem) or "bushes" in growth habit. IMPE "bushes" may need the occasional "drastic prune to the ground" or they become over-woody - this may be less of an issue if there is plenty of space, as it's mostly due to pruning the bush back to a reasonable size.

Answer 2

Pot them up individually for the time being - its absolutely the wrong time to plant in the ground with temperatures like that, best planted when the weather cools down towards Fall. Make sure each pot is deep enough for the roots that have already formed without cramping or breaking them, but also that the pot isn't so large more than two thirds of it is just potting medium, not occupied with roots. Water in well once planted up, and keep well watered as necessary until such time as the weather is more suitable for planting out. This will mean each plant will have a good root system of its own when it is eventually planted.

As to how much space should go between each one when planted out, need to know which varieties they are in order to work out height and spread, and therefore planting distance - I'm assuming they're Hibiscus syriacus, but they might not be, even though the leaves showing in the picture look more or less right.