MIMOSA: 22 April 2004
NT in the U K e-mails: I have a Mimosa tree and it needs cutting back, as the holly and oak behind it have pushed it over. I would like to move it, but that just isn't an option, so I was wondering if I could take some cuttings of it and if so how and when do I do it? I understand there are two kinds of Mimosa. The one I have has a feathery leaf, if that makes a difference.
R J Harris replies as follows
1) We are talking about the acacia mimosaceae, a plant family which is made up of at least one thousand related deciduous -- i e, sheds its leaves annually -- or ever-green trees, shrubs and climbers. It is grown mainly for its delightful, pale yellow flowers and foliage in the tropical-to-warm and temperate regions of Central and South America, Kenya, South Africa and Australia. And, of course, quite freely here in Cornwall in the U K, for that is where NT e-mails from, I know. [Ed: And Shropshire, U K, for a beauty is blossoming right now in a very protected spot not two hundred yards from my office.] In Britain, where it grows in the open only in the south, it is rated as half-hardy to frost-tender. Elsewhere in fog-bound England, and in sodden Ireland, blizzard-swept Scotland and rained-out Wales, it clings on to life under glass, containerised, rooted in loam-based potting compost -- John Innes No 1 or No 2 -- and fed and watered assiduously to keep it in the land of the living.
2) To propagate the acacia mimosaceae in the U K, you use a greenhouse or a naturally-lit area in which an ambient temperature of not less than 65 degrees Fahrenheit can be maintained. You sow the seed in the Spring. You start by soaking several of the seeds in warm water until they are well swollen, and then you sow them in John Innes seed compost in a large pot spaced some two inches apart from each other in each direction. On germination, the resultant seedlings are separated carefully and then potted on each into its own individual pot containing John Innes No 1 or No 2 compost -- and again, in a constantly-maintained temperature of 65 degrees Fahrenheit temperature. [Ed: the section COMPOST: John Innes in 'R J Harris's Moon Gardening' offers a full explanation of the John Innes composts.]
3) As a different and quicker way of securing young plants, rooting is possible. It is done -- and really very easily, for this is an accommodating plant -- with semi-ripe cuttings taken in early Summer after the parent plant has completed its flowering stage. Cuttings' material is located not at the tender tips of the branches, but slightly down, where the previous year's growth is to be found. Take a half dozen or so cuttings, each roughly -- depending upon the type of acacia mimosaceae being propagated -- a 4-inch to 6-inch length of semi-hard wood, with all growth removed from it for about a half of its length. The other half is left as it was on the bush or the tree. Working in a greenhouse or a naturally-lit area, and maintaining an ambient temperature of at least 65 degrees Fahrenheit, insert the de-leafed sections of the cuttings into John Innes seed compost in a large pot. Space them sensibly around the perimeter of the top of the pot, two inches away from it. Six to eight months later, in the Spring, when the cuttings have developed root systems, transfer each into John Innes No 2 potting compost in its own 4-inch pot. Do so with the greatest of care, for the roots of these new developments are fragile in the extreme.
4) If the final planting out is to take place in Cornwall, or where local experience is that the acacia mimosaceae survives in the open, immediately transfer from where the 65 degrees Fahrenheit has been maintained to a cold frame of the kind that can be protected against the frost. Hold the cuttings there for twelve months until they mature. Then choose what is obviously the heartiest of them, and transfer it from pot to selected location. Do this in the classic way, as described in great detail in 'R J Harris's Moon Gardening' -- i e, transfer the total assembly of root ball in compost surmounted by a flourishing young plantlet from pot to pot-sized, pot-shaped hole in the ground. One key to completing this successfully is a prolonged soaking of the potted plant prior to transplanting. 'R J Harris's Moon Gardening' devotes a lot of space to this important technique. Another key is choosing the best moon time -- the start of the first quarter (New Moon) in the month chosen for the planting out.
5) If the acacia mimosaceae is to live in those U K regions not blessed with Cornwall's climate, the plantlets are held for twelve months in their four-inch pots, still in the greenhouse, still in the ambient temperature of at least 65 degrees Fahrenheit. The stoutest of them is then transferred in annual stages -- six-inch, eight-inch and ten-inch pots being employed -- to a twelve-inch pot filled with John Innes No 2 potting compost. Throughout, and afterwards, its home is the greenhouse. It is extremely unlikely to live beyond its first U K winter if it is committed to the open air, whether still potted/containerised or de-potted and then planted out.
6) When the acacia mimosaceae is developed in its native land or where it finds the climate that it must have if it is to survive, the greenhouse or equivalent elements can be omitted from the total development programme, everything being done in the open at the chosen location with the seed or the cutting as the starting point. The ideal time for this, in the chosen month, is when the moon is at the start of its first quarter (or New Moon).
7) NT's tree must be pruned only after the last of its flowers has fallen to the ground. It does not welcome drastic pruning, but light pruning it will accept. And, of course, the pruning is best done -- like the taking of cuttings -- with secateurs in tip-top condition and razor sharp, and at any time during the fourth quarter of the moon. The latter reduces bleeding and consequent loss of sap to the minimum.
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