Why has our Acer Palmatum Atropurpureum gone straggly?
By Valandy
Cumbria,
United Kingdom 
We have had the Acer in a large pot for ten years and last year it was magnificent, but this year although it started well it has gone very straggly. We wondered about planting it in the gravel in the small front garden which has the sun in the mornings and is also where it is now, but worry it might grow too large. Also it never goes bright red in Autumn, what could be the reason for this?
22 Oct, 2009
Answers
Also add, this particular variety is usually seed grown and can be very variable for autumn colour
23 Oct, 2009
Sounds like it needs root pruning.
Pot growing maples need to be repotted at least every two years.
Removing thick roots below soil level encourages fiberous root growth which is to be desired. Plant in free draining compost. Good drainage is essential.
Don't overwater. Use a chopstick or a wooden bbq skewer to determinate if it needs watering. Push into soil amongst the roots, leave for five minutes then pull it out, if its wet don't water. If its dry or barely damp, water until water flows from drainage holes in pot.
24 Oct, 2009
Thanks everyone for your advice, the Maple is around 6ft tall as it stands in the pot so maybe a bit of root pruning and repotting will do the trick.
24 Oct, 2009
Height for this plant is about 13 feet (in the ground) after 10 years, eventually up to 40 feet, though slow growing, so maybe you don't want it in the ground. You could though, put it in the ground and keep it pruned back, but either way, it sounds as if it might have outgrown its pot, so you could just try repotting it into something larger, or replenishing the compost by removing what's there already, and pruning back the top in early January to reshape the plant. Autumn colour on these trees varies from plant to plant and year to year, no guarantee of lovely reds in the autumn, I'm afraid.
22 Oct, 2009