Trachycarpus does not make it's best growth in very hot weather (especially with very warm/hot evening). They grow better with moderate temperatures (60-80s). As the temperatures are cooling down, they may push more growth for you. This is one reason they tend NOT to really thrive in South Florida.

Leaving them in the pot should have minimized or prevented any transplant shock. Translant shock could easily stall them completely since June.

They will become severely rootbound, if they aren't already, which will mean the pots will dry out quickly due to having some much roots in touch with so little soil, in touch with the container and with other roots, hindering uptake of moisture and nutrition.

I agree that you should hav seen no shock and some growth over the summer. I don't know why you didn't.

We have a lot of very tall Tr. forunei in San Antonio, like 8 or more feet.

Our weather in San Antonio can be 75F min and 95F max from March to October. They may not grow much in such untemperate heat, but they certainly survive for many, many years.

The heat stalling Tr.f. in the summer does sound like the best explanation, leaving me worried about those Tr. f becoming "bonszai'd" later if not already.

I am speaking solely from firsthand experience and local observations, when I say that T. fortunei (windmill palms)planted in full sun in the DFW area, don't do as well as those planted in partial sun.

With 42 days at or over 100f this summer and them being planted in June that is most likely why they are exhibiting heat stress and a slow growth rate. I have 6 windmills and their best growth is in the spring and fall when nightly temps are in the 50's and 60's. The overnight lows in the 80's really seem to almost stop their growth in the summer.

I have read of some success in pot planting but I have never tried it myself. Do palms planted in pots break through the thicker and larger pots or is it more intended for the thinner and flimsier pots you sometimes get when buying smaller sizes?

Keep them very well watered while it is still warm and good luck.

David

Thanks for all of your comments! I really thought the heat was my biggest issue seeing that they are in full sun and I had read that they do better in part sun but I have seen others around town who've planted theirs in full sun and though the crowns are small they are still full. Here is a pic of the two trees about a month ago.

As for remaining root bound I believe with the slits I cut in the sides after they were in place they should have a good start on ripping those pots apart.

Even here in Northern Virginia where we had a few days in the 100s, but many more in the 90s with overnight lows in the high 80s a few nights and more in the low 80s, my Trachys stalled out in the middle of June. These have been in the ground a two years and they never liked it much when the temperatures were high and in direct sun. We had some very wets spells that allowed them to grow in July, but as soon as the rain stopped, they stopped growing. I watered mine like crazy to keep them from getting too much damage, but I still got several fronds that suffered sun scorch on the 6 I have planted in direct sunlight. Those that were in partial shade did much better. Now that it has cooled into the 70s and 80s with cool 50s and 60s at night they are starting to grow again. Getting mine through the winter has always been the challenge, but the summer is also a time of concern from the heat stress it subjects the palms to. The sabals I have love the heat and humidity and don't suffer from this malady. Same goes for the needle palms as they really took off this summer.

I have never had good luck with pot planting in the ground and I think your Trachys will do better if they are allowed to develop a good root system directly in the soil.

Well... they might do better if they were planted directly in the soil but with the hot temps this summer they might have substained more shock had I not planted them in the pots... They didn't appear root bound in the 95 gallon pots and I cut slits every 6 inches. I guess I could go back, remove some dirt around the pots, cut the pot apart and slide it out before replacing the dirt. That would be a chore but very well worth it if it increases their survival rate. What is the concensus on me removing the sides of the pot?

The pots in my experience offer nothing over planting a palm in well amended soil on a mound or berm with a good layer of mulch to hold in the moisture. Restricting the roots in pots even in the ground creates a barrier for new roots and may actually add to the stress. I am not trying to sound like Mr. "Know it All" but, I would get the palm out of the pot and backfill the area with compost/native soil mix. Add more mulch, add a little epsom salts and water well, and there should be an improvement. Take my advice with a truck load of salt, but I think it would really improve the health of the palm. Best of luck and keep us posted.