Gardeners' queries

Press, 17 September 1976, Page 10

Gardeners' queries

Our lemon now has its crop of new buds but I think the tree should be pruned down a bit. How far can one cut a lemon back? (2) Regarding mushroom compost a friend applies six bags of it on the ground every year. I find it is inclined to cause a whitish crust on top of the soil and it made me wonder about it. (3) My flowering aspidistra was divided into two. Mushroom compost was mixed with the soil and now some of the leaves are curling up lengthwise. What would be the cause? (4) By covering it well, our rose boronia has survived the winter, but now it looks pale and dry. Should it be pruned back a bit?—E.W. (Christchurch)

Lemons are remarkably tolerant of quite severe cutting back and even after having suffered greatly as the result of frost they have often shown this ability to recover. When cutting back,' the objective should be to try to improve the structural formation of the tree rather than just simply cutting it to reduce it in dimensions. (2) Mushroom compost tends to vary its composition aS individual growers have their own recipes. Most mushroom compost, however, has a high pH (alkaline reaction) and should not be used in conjunction with acid-soil-loving plants. The white surface encrustation of the soil is a harmless fungus growth and will disappear with moisture and cultivation to the ground. Six bags of this compost can be a very negligible amount or it can be excessive. It all depends on the area to which it is applied and, of course, the size of the bags. (.3) Aspidistras are very dependable and hardy plants which will tolerate conditions which very few if any other Indoor plants will stand. It is possible that the compost which you have used in your soil mix does not agree, with your plant, but inspection is the only possible way of trying to determine the

cause of the problem. An occasional application of liquid manure will help to maintain gloss on the leaves. (4) Boronias are generally capable of surviving the winter unprotected unless they are growing in an unsuitable situation. It is possible that your plant is suffering from dryness or the too close attentions of an animal. Boronias are tolerant of light pruning which helps to keep them in a denser, more bushy state. It is advisable to prune them back immediately after flowering has ceased. Some time ago someone wrote to you saying that their Puya alpestris flowered for the first time in 25 years. Will I likewise have to wait so long before my four-year-old plant flowers, or is there something I can do to it to encourage it?—N.N. (Christchurch)

Just how early in life Pu.vas will flower is not known, but under local conditions eight to 12 years is regarded as about average. Good drainage and a soil on the dry side together with a position in full sun is requited. How to make them flower earlier than the average is not known.

Could you please identify the enclosed plant for me and advise how it can be got rid of. It is growing in the lawn and seems to be taking control.—J.M. (Christchurch) The plant in question is Hydrocotyle species, a very tenacious weed which can become invasive in lawns but predominantly in those which do not flourish and where the soil tends to remain damp. The perfect control for this weed in lawns does not appear to be available yet, the combination of picloram and 2,4,5-T giving the best results.

Now that my lawn is growing once more, large patches of prairie grass have become evident. Do you know of any way to eradicate it, other than chipping out each plant,

which I am at present endeavouring to do?—"Problem" (Nth. Otago) The tussocky nature of prairie grass, its coarseness and its suppression of fine grasses, makes it an undesirable plant in the lawn. It is, however, regarded as a short term perennial which does not tolerate close mowing for too long. There is only one chemical at present which can be appUed to eradicate a particular grass (Poa annua) without at the same time damaging all others.

Can you please give the name of the shrub of which I enclose a piece.—E.L. (Christchurch) Stachyurus praecox, a most desirable late winter to early spring flowering deciduous, tall growing, hardy shrub which deserves to be more widely grown than it is.

Yew tree problem: this tree, having been more exposed to winds and sunshine after being crowded by other trees now looks unhealthy, the leaves browning and falling off. Can it be saved? Can you tell me the name of the enclosed creeper, please, which has small trumpet-like whitish flowers? Could you suggest some shrubs which would tolerate dry conditions but would need frost protection?—H.W, (Darfield) Yew trees are inclined to suffer from very exposed positions. Tills is more likely to occur in the case mentioned because the surrounding shelter has been removed. Providing that no other problem prevails the onset of better weather should see a flush of new growth. It is recommended that (he tree be given a light clipping all over to encourage this. The creeper may be a honey suckle but it would be preferable to see a specimen in flower before verifying this identification. Shrubs which tolerate dry conditions but are not frost hardv include some of the smaller growing callistemons. accacias and banksias, proteas, Pomaderris kumeranou, calliandra, various ericas and some of the grevilleas.

We have a very healthy looking daphne about 15 years old and every year at this time it is a mass of bloom. This year there is only one cluster of flowers. Could you tell me if this can happen to a daphne bush? It is sheltered from the frost. —E.F. (Christchurch)

It would appear that many daphne bushes have been sparse of bloom this year and although this is most likely due to climatical influence the exact cause is not known.