Ohio? What a coincidence. I was talking about hydrangea hedges and discussing that one could go to the Cincinnati Zoo to see an example of a hedge made using oakleaf hydrangeas. They have one hedge, not too terribly long but it looks nice and in the Fall, when the oakleaf leaves turn colors, it must be very nice.
Mathilda Gutges is a good one but it unfortunately the bad distinction that is one of a few hydrangeas that did not make it for me. I remember getting it at a now defunct plant nursery and planted it in front of a window looking north. I had issues watering it and it did not come back after the first winter. Over here in the Summer/Fall, temperatures get to the 100++ and I basically forgot all about it. I have to monitor these shrubs and provide water by hand when temps rise to the 100s daily and I did not water it. The drip irrigation probably gave it some water but being on its first summer, it probably needed more water and did not get it. Sigh. Mea culpa, not MG's. I therefore suggest that you place the pot in a location where you will not "forget" about the plant either. Regarding your questions...
What type of soil to use... There over 17,254,802 different best types of potting soils out there! I know because the Internet says so! Hee hee hee! But really, you can make your own or use any potting soil that says it is for azaleas, camellias and-or hydrangeas. There are some people who like to make their own potting soil and if you want to control the items used to make it even more well-draining, that is fine as well. Hydrangeas like well-draining, acidic soil that is as evenly moist as possible. Periods of dry soil, followed by wet soil and back to dry again are not good. Have a plan for watering purposes. Now the soil and the plant will not complain but as soon as summer arrives -especially the first summer- the plant may complain so make sure it can whatever water it needs. You can set up and automated irrigation system or just plant to water every few days.
On the first summer, a hydrangea will be fighting what is called transplant shock. It was grown using perfect conditions at a plant wholesaler and now it finds out there is such a thing as summer and wind. Until it develops a large root system, it may suffer from episodes where those big ole leaves loose moisture faster than the roots can uptake moisture from the soil; as a result, the leaves wilt and the plant looks pretty sad. The trick with this is to determine if the soil is dry or not when the leaves wilt. If you insert a finger into the soil to a depth of 2" or use a soil moisture meter and it says the soil is dry then you have to water quickly it so it will recover. But if the soil is moist then you can leave it alone and the leaves will recover on their own by nightfall or by the next morning. If you see that the leaves are browning from the edges inwards instead, it is having some of these dry-wet-dry periods so you either need to water more or more often.
Size of the pot.... some people start with the same plastic pot that the plant came in but since those plastic ones get hot in the summer and the roots do not like it hot, you can start a progression if size until you get to a size appropriate for MG's 5x5. Note that you get those advertised sizes in places where the growing season is long (meaning the South and the coasts) so do not be surprised if growth tops out as 4x4 or so. I happen to have a 12" pot and have used it for starting some mail order hydrangeas that a friend sent me. So I would use a smaller size until the plant gets bigger and needs more room. If you see the roots circling around the pot, that would be a good time to prune the roots and transplant it to a bigger size. Just stop at the right size that you want to use.
The frequent watering makes the fertilizer minerals leach out so need to fertilize more often than if the plant was on the ground. Products like MG can be used, just be aware that they have to be applied often. You can also use general purpose, slow release fertilizers with a NPK Ratio of around 10-10-10. Those will last longer so you do not have reapply every hour. I have on hand a lot of cottonseed meal, organic compost and composted manure most of the time so when I received a batch of a dozen shrubs from my friend, I applied some granular fertilizer (Osmocote 10-10-10) and, later on, I used what I had on-hand: some of all of the others I mentioned. I have a soil test kit that I bought at Lowe's. Pretty cheap and inaccurate but it can flag when the potting mix has little nitrogen, phosphorus or potassium. I would use the test "every now and then" (2-4 weeks?? I can't exactly remember) and was just on the lookout for when the solution turned colors indicating low levels. After a year or so then you get an idea of about how often to apply the fertilizers. Do not forget to add some acidifier compounds too since these will also leach out along with the water. If you notice that the leaves are turning yellow-ish with the leaf veins remaining dark brown, you need to add some of these things. You can use greensand,
Pruning... hydrangeas really do not need pruning if you place them in a location where the shrub can reach its advertised size at maturity (commercial term for "eh, about 10 years or close to that). Some minor pruning is ok: (1) You can prune stems that cross or stems that happen to grow much larger than the others. (2) prune down to the ground any stems that did not leaf out by mid-to-late May. Note that MG develops invisible flower buds at the ends of the stems in July-August (July down here; later north of me) so if you ever need to prune, do it after the plant has bloomed and before the end of June to be safe. Deadheading of the spent blooms can be done at any time but note that deadheading is not the same as pruning. It just means you cut the little string that connects the bloom to the stem. You do not want to cut the stem itself because in winter, it has invisible flower buds at the ends of the stems.
Mopheads like MG do best in morning sun and after/evening sun so place the pot in a location where you can control this. Especially during the summer. I give the new hydrangeas several days (maybe a week tops) of bright shade before I move it to a place where they got 1-2 hrs of morning sun and then to their final place where they had to get shade by 11am to 12pm. Being up north, you might be able to coax a little more sun but remember that the sun is an issue in the summer, not now in Spring. You can also drive around looking to see where people plant hydrangeas near you to get ideas.
Winter can be a problem for mophead hydrangeas. Those invisible flower buds that they develop in July-August need to survive winter so they open in Spring and so you will get bloomage. So once the plant goes dormant, bring the pot into the garage, basement, shed, etc and water it every week or every two weeks. Of all possible places to put the pot, select the one that gives more protection from cold drying winds and cold temps. Then take it outside in the Spring, about two weeks after your average date of last frost. Very cold temps or lack of water can kill these flower buds during winter. If you notice that the stems did not leaf out by mid-May and that new growth is coming back from the crown, the flower buds at the ends of the stems did not make and there will not be bloomage that year. I just got hit with this problem even though I am in Zone 8a. This last winter was very mild and even though most of my hydrangeas went dormant, many of them started leafing out from the crown back in February (later for you).
Not sure how well MG might do bloom-wise if your zone is Z5 cold though. Zone 6 is starting to push the limits of typical mopheads so the plants needs to be brought inside or people have to put winter protection around the bushes when the plants are grown outside. Mophead hydrangeas that bloom like MG are said to bloom on old wood only. But there are other mopheads that bloom on old wood and new wood that are useful in cold zones. People call them rebloomers. They develop flower buds in July-August, the buds open and bloom in the Spring; theeen, they develop new flower buds again in the summer and bloom again in the summer months. These rebloomers can be useful in cold places (Z5) where mopheads that bloom on old wood have blooming issues (cannot reliably bloom every year). Signs of winter issues: they may loose stems during winter if not given winter protection; all growth comes from the crown. However, the rebloomers develop a second round of flower buds in late Spring or early Summer and have another flush of blooms later in the summer. So you still get bloomage (not early in Spring but during the summer). The Endless Summer Series, the Forever and Ever Series and the Let’s Dance Series of hydrangeas are some examples of mophead collections that rebloom. Note: some people in very cold locations have had issues with the Original Endless Summer not blooming at all so take the Original with a grain of salt.
Does that help you?
Last edited by luis_pr
on Thu Apr 27, 2017 11:55 am, edited 1 time in total.