Stunted/dormant growth on Hornbeam seedlings

[zeejet]

I have some Korean hornbeam seedlings that pushed new growth in March/April but have not grown at all since then. They have been properly watered with mild fertilizer application throughout the year but were watered with very hard water from January through June - I eventually got an RO system and shadecloth but I think the damage is done. There is moderate leaf scorch on all of them.

The only exception is one of the seedlings is currently sending a side shoot but the rest of the tree and all other seedlings seem entirely dormant. It’s only about 80F here in coastal San Diego throughout the summer (occasional heat spikes or dry winds from inland) so I doubt it’s summer dormancy. The shoot seems healthy and does not burn (it pushed AFTER I switched to RO and installed 40% shadecloth).

What could be preventing further growth on the rest of the seedlings? I know KH are slow growers but is it really “single flush”? Or is my horticulture completely off?

I also recognize that KH is not likely to thrive here in my climate (Zone 10b - I only realized this after purchasing them) - could that be a reason? The seedlings were shipped from NY in the spring so they should have had proper dormancy at least going into this season.

Any insight would be appreciated.

Spring growth:


Scorched spring growth:


Healthy side-shoot:

 

[leatherback]

The keaves show classic signs of root challenges in warm weather. It might be too much fertilizer. Or you cannot water properly because it is in a pond basked (The person inventing those is responsible for loads of dead trees). Or too saline water.

 

[penumbra]

pond basked (The person inventing those is responsible for loads of dead trees).

In defense of these baskets that were actually designed with water lilies in mind, I'm sure I have close to 100 trees in pond baskets. Some are in their 4th year. They do come with a learning curve though, and I agree that many people have misused them leading to the demise of their plants.

 

[zeejet]

The keaves show classic signs of root challenges in warm weather. It might be too much fertilizer. Or you cannot water properly because it is in a pond basked (The person inventing those is responsible for loads of dead trees). Or too saline water.

Thanks for the insight Jelle!

Most of my trees are in pond baskets, wooden grow boxes, or Anderson flats. I have no issues with any of them except the hornbeam seedlings so I'm skeptical that they are leading to the causes of the dormant growth. It's still entirely possible that the soil may be a problem though - I guess there's nothing I can do this season - will have to wait until spring to do root work and diagnose further.

There's also very little fertilizer (two smaller baskets of Osmocote Plus from spring that are likely completely spent by now) although I suppose I could remove them and see how the trees responds.

I also water using RO so there's no salt in the water - although as mentioned, I was watering with hard water during most of spring so the damage might not be reversible this season.

 

[Cypress187]

Or you cannot water properly because it is in a pond basked (The person inventing those is responsible for loads of dead trees).

What happens / why can't pond baskets be properly watered?

 

[zeejet]

What happens / why can't pond baskets be properly watered?

I think there are two camps in this debate. One believes in the general theory of air pruning and improved root ramification/development when the sides of the container have open structure for ample aeration. The other camp believes that this is overstated and that the risk of underwatering of drying out is far greater than any benefit gained from the improved aeration at the sides of the container.

I don't think this is definitive. I've seen some pros who use pondies while others (like Jonas Dupuich of Bonsai Tonight) have complicated or negative views about them.

I didn't mention this before but I wrap the sides in plastic wrap to prevent drying but will remove the wrapping once every few months to physically prune back the roots that have escaped and are wrapping themselves around the container behind the plastic wrap. This allows me to keep some water retention while still allowing easy access to the longest roots throughout the seasons without needing to repot.

 

[Johnnyd]

When we go out collecting hornbeam I frequently find them near creeks. Point being they like soil on the moist side. I know it has been written before on this forum, pond basket are most frequently used on species that like to dry completely between watering, for example, pine trees. That being said, I have only lost one hornbeam in 8 years. Yes, it was in a pond basket. I think if you slip pot the entire basket in a larger container it would help. Good luck!

Edit: I skimmed over the 10b part. This is problematic.

 

[leatherback]

What happens / why can't pond baskets be properly watered?

I find if the baskets are not fully filled it is much harder to get the core of the rootbal properly wet, as well as the rootball drying out much faster than you would in a normal pot. I have a few junipers in pond baskets to trial and see what happens to the roots. I do notice reduced growth which I attribute to the dificulty of getting water well into the rootball, without half coming out at the sides.

 

[Dabbler]

I have 4 hornbeams and they like water - My guess is your too hot in your area or not enough water - or both - and judging by the half filled pond baskets - what every one else said

 

[River's Edge]

Pond baskets present one of the most difficult containers to maintain moisture. This necessitates changes in soil components and watering practises in order to use them effectively. Typically one would choose smaller particles, more moisture retentive components combined with more frequent watering and a more temperate climate for their use.
Several problems with this particular situation. Not to mention the lack of mineral content in RO water. The use of RO water requires adaptation of fertilizer to compensate for the demineralization from the RO process.
Korean Hornbeam prefer a moister environment and respond very poorly to desiccation
Multiple factors at play here!. Important to use processes that suit the climate, species and our own practises.
I concur that partial filling is not the best way to use pond baskets due to their free draining fast drying nature!

 

[johng]

I didn't mention this before but I wrap the sides in plastic wrap to prevent drying but will remove the wrapping once every few months to physically prune back the roots that have escaped and are wrapping themselves around the container behind the plastic wrap. This allows me to keep some water retention while still allowing easy access to the longest roots throughout the seasons without needing to repot.

Seems you have already discovered that pond baskets are not ideal and refuse to acknowledge it... I would never consider using them with a hornbeam and most other deciduous trees. If you like the air pruning features try switching to fabric pots...far superior in my experience. No circling roots or problems keeping them moist.

 

[zeejet]

Seems you have already discovered that pond baskets are not ideal and refuse to acknowledge it... I would never consider using them with a hornbeam and most other deciduous trees. If you like the air pruning features try switching to fabric pots...far superior in my experience. No circling roots or problems keeping them moist.

Perhaps you're right haha. I also really don't to waste these baskets and have to buy other ones at the moment. The saran wrap approach works for now.

Also, eveyrone here says KH loves moisture, which is new to me as I've been following Mirai's care guide, which says the opposite:


I have another seedling in a 1-gallon nursery pot and is kept moist with additional bark in the mix. Same fate - no growth since spring flush.

At this point, I may need to separate the seedlings further and do some experiments with the soil comp and container choice.

 

[River's Edge]

When I read your adaptation I simply thought you found a way to increase the pond baskets effectiveness in that situation. It was a common modification, I used duct tape to close off the top 3 or four inches for a similar effect without having to cut escaping roots.
With Anderson flats that are placed on smoother benches I drill holes in the sides to aid drainage. Nothing wrong with making changes as we progress. Fabric exposed to the air can act like a wick to cause faster drying out and can often lead to extra watering as opposed to ceramic pots.