Acers – Care and Cultivation of Acer Palmatum

The speaker at our February meeting was one of our own members, Joanna Baxter, who gave us a fully illustrated and beautifully presented talk on the cultivation and care of Acer Palmatum. There are 128 species of Acers, or maples, divided into 700 cultivars. Acer Palmatum is just one of these species and cultivation has resulted in over 1,000 different cultivars.

Joanna’s talk was the story of a love affair which began while away with her newly married husband but was centred on a little scarlet plant that attracted her with deep fascination. She couldn’t resist buying it and it marked the beginning of a collection of 103 acers of which 98 are cultivars of acer palmatum. Joanna’s garden is now entirely devoted to trees and shrubs.

Joanna demonstrated to us very convincingly the fascination of acer palmatum ( referred to from now on as ’acers’). They come in a fascinating variety of trees and shrubs which range enormously in size, shape and colour. Their distinguishing feature is the nature of their leaves which have between five and nine lobes separated in a way which resembles fingers spreading from the palm of a hand; hence ‘palmatum’.  They are  beautiful, shapely and strikingly colourful plants. The colour not only varies between cultivars but one cultivar may change colour three or four times a year. The leaves on some varieties may at time be bi-coloured and colour variations extend to flowers and fruit. The fruit form like little helicopters.

Acers make excellent companions to other plants but if you are looking for a combination of particular colours this will not be consistent throughout the year. Leave the acer space because their shallow but fibrous and spreading root pattern doesn’t like competition. Epimedium make a good companion plant.

Colour depends not just on the cultivar but on the position, soil and moisture level in which they are grown.  The conditions which suit most acers are acid or neutral soil in dappled shade without full or prolonged exposure to sunlight but there are exceptions to this. Green varieties are more sun tolerant although red varieties need some sun. They can be grown in the ground or in pots so that even those with alkaline soil can enjoy the beauty of acers by growing them in pots. Ensure the pot is widest at the open end or you will never be able to get the plant out without breaking the pot.

Acers are widely available but the cheapest plants may well be poor specimens and wrongly labelled. Look out for a strong growing and well-balanced structure. Get the best plant you can afford, get the right plant for the right place and see that it is labelled. Aluminium labels are best.

Joanna then dealt with the care and cultivation of acers and again stressed the importance of the right location. Moisture level is also important . Acers need to be kept moist and never allowed to dry out but they don’t want to be waterlogged. Plants in the ground won’t need feeding but mulching with bark is beneficial.

After two or three years plants will need some pruning. Prune in winter and before there is any danger of the sap starting to rise. Removing dead or damaged wood and cut out any crossing or interfering branches and thin straggly growth. Use sharp bypass secateurs (not guillotine) and don’t overprune.

The care and cultivation of pot-grown plants is very much the same as in the ground apart from the use of a little long lasting fertiliser. If you grow pot plants on soil rather than  a hard surface use a saucer to prevent the plant putting roots into the soil. Joanna recommended this soil recipe; 1/3 good quality multi-purpose compost, 1/3 ericaceous compost, 1/3 John Innes compost – No 3 for ground plants and No 1 or 2 for pot plants. One pound or more of horticultural grit or sharp sand or a good handful of vermiculite or perlite.

Acers may have some problems, chief or which is leaf scorch which can come from wind. sun or frost. Frost can be the most damaging but recovery in time is likely so don’t despair too soon. Try to plant in situations protected from frost. Watch out for black and green aphids and treat with diluted washing-up water. Verticillium wilt can be a real problem. Cut out dead wood but a badly infected plant should be removed.
A small selection of photos:

Click for more photos from Flickr

Our next meeting will be on Tuesday 20 march when nursery owner and Chelsea exhibitor Annie Godfrey will give a talk entitled “Good in Bed” (Annie is a specialist in herbaceous plants)

Jeremy Arthern

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