Plants - Any Questions? - page 2


Q.  About three months ago I bought a Bonsai Tree named Serissa Foetida (Tree of a thousand stars, since we have had it the leaves have gone yellow and are constantly dropping off. We have followed all the advice we can get on watering and feeding and then as a last resort we have re-potted it then still the leaves are dropping.

A.  Where are you keeping it? Bonsai need to spend most of their time outdoors ideally, they don't really like modern houses in particular far too warm and dry. As it's almost still winter it'll be too much of a shock to put it straight outside, so a sheltered but cool and humid area would do. When you bring it in again, get a humidity tray to stand it in. This particular species needs a minimum temp of 7C, so in temperate regions is really a cool greenhouse plant in winter i.e. lots of light and humidity, that'll be what's wrong with it.


Q.  May Miscanthus "zebrinus" be grown from seed? I've heard contradicting rules of thumb pertaining to Miscanthus. Please describe the seed itself, and when to pick the seed at its peak.

A. The short answer to your question is no. Miscanthus "zebrinus" is a recognized variety and as such the specific genetic combination that makes up this variety can only be obtained by vegetative propagation of the variety itself. i.e. by splitting plants to make more that are exactly the same as the parent.

It is possible however to grow Miscanthus hybrids from seed to obtain a variety of forms, some of which have striated leaves in a similar manner to zebrinus. I presume that from your question you have a Miscanthus you wish to gather seed from. Late summer / early autumn is the best time to gather the seed, place a paper bag over the seed head and shake it around, the seed should be dislodged with a lot of chaff. Miscanthus seed are usually around 1/16th to 1/8th of an inch long, mid brown and spindle shaped.


Q.  I have been growing Impatiens for years, at the end of the season I collect the seed pods for use the following year. Last year I planted some double-headed Impatiens, these however did not throw off seed pods, does this mean I need to buy seeds every year?

A.  The short answer is probably yes. The double Impatiens that you grew will be further removed from the wild-type plants than the types that you normally grow. They are more altered and helped along by the nursery to reproduce than "normal" types. Hence they are more reluctant to set seed if they will do so at all.

You didn't say whether or not you grew the doubles from seed or bought them as plants. They may have been F1 hybrids and so if they set seed at all won't ever come true to the parent, or from a variety that needs particular conditions supplied by the nursery to set seed. Conditions that don't seem to exist in your garden!


Q.  Last year I acquired a Hydrangea from the midlands, (I am in East Anglia). The hydrangea is in a large tub. When is the safest time to replant the hydrangea from tub to garden and are there any special precautions I should take? I look forward to your answer as this hydrangea is very sentimental to me.

A. The best time to plant your Hydrangea is now - in the dormant season (November - March). The plant will be better off in the soil as the roots will be more protected from frosts that could freeze solid the above ground container. Give it a good start by digging a hole about twice as big as the pot and then half filling it with organic matter - well rotted garden compost or stable manure if you have it, peat or something similar if not. Fork the organic matter into the hole so that you make a transition between garden soil and what your hydrangea is currently growing in. I usually add a sprinkling of a slow release fertiliser such as blood fish and bone or Grow more. Plant in the hole and water in well, not so much to give it a drink, but to settle the soil around the roots. Hydrangeas like sunshine but aren't that fussy, it won't like full shade though. 

The soil that a hydrangea is growing in may affect the colour of the flowers. Blue flowering varieties will change to pink if grown in an alkali soil. If this affects yours, you can buy proprietary chemicals from garden centres to change it back or try the (slower) time-honoured method of burying razor blades and rusty nails around the roots.


Q. I am interested to know if my amaryllis will flower again. It was really splendid but now I am not sure if I should throw it away or try and grow it a second time.

A. It will if treated properly, but may well miss out a year which is normal as the bulb you bought will have been specially treated.

Keep it warm and sunny, watered and fed regularly as long as it has green leaves to build up energy for next year. When the leaves begin to turn yellow, stop watering and feeding and it dry out in its pot. Don't repot unless it is obviously too big for the pot that it is in. Cut the dried out leaves off just above the neck of the bulb. They need a rest of at least a couple of months with no leaves if they're going to flower again, otherwise they don't know what time of year it is.

It will start to sprout again during the winter, when it does so water again and bring into the warmth.


Q. We built a large raised herb bed last month which we filled with bought-in topsoil. The soil is dark, but very fine and sandy. We planted with established herbs and most seem fine, but we have had several "goes" with basil and Thai basil from several sources. In spite of daily watering they sicken and die within days. There is no sign of insect attack. Is it too cold for them in Norfolk, or could it be the soil? (We haven't tried shouting - Plant Lore.)

A. Basil is a very much a fair weather plant. It likes warm, sunny, sheltered conditions and little else is tolerated. It's probably just too cold for them still. The temperature has gone down quite low in the last month at night.

Basil is best grown on a sunny windowsill or a conservatory. I usually plant some out in the summer in the sunniest place that I can, but it never does as well as that under protection and it dies off well before the first frosts arrive.


Q.  I have a stock plant from last year but I didn't prune it and it is woody and the flowers are not good. Should I have pruned it?

A.  Stocks of all types are usually grown as annuals or biennials for the reason that you describe. There isn't really anything that you can do to make your stocks like they were last year, pruning may certainly help, but far better is to discard them after they have flowered and start again next year with new seed.


Q.  I planted privets (Ligustrum amurense) last year this past winter something ate some of the bark from the bottom up approx.2-6" on 5 of our plants what do I need to do. will I lose these 5? Your response greatly appreciated. Thank You in advance.

A.  It's difficult to tell if you will lose the plants or not. If the bark is completely ringed i.e. a gap in the bark at any point all the way up the stem, then you will. If there isn't, then you may be lucky, it depends on the extent of the damage. What can you do? nothing really for the damaged ones, but I'd get some spiral tree guards as soon as possible and put them on all your plants until they're large enough to be able to survive alone. These are plastic spiral devices that guard the bark of the tree / shrub against grazing by rabbits or deer, they're not pretty, but they do work.


 

Q.  As my greenhouse is overflowing with annual seedlings I decided to find out how much of a risk it would be to plant some out in early May. From 1969 to 2000 Cambridge (a nearby weather station) shows May as having a good positive average temperature and on average 3 days of air frost every 10 years. Does this mean that the usual advise not to plant until Mid May not apply so much here and does air frost kill half hardy annuals?

A.  Always a difficult one. I live fairly close to you and always wait until at least mid-May if not the end before I put out any half-hardy plants. I have put them out in early May before now and they have survived, but I've found that the frequent damp or sometimes colder conditions mean that they get a knock-back, so little or nothing has been gained.

It's true that there is little risk of a frost now, but if there is a frost, then your plants will be damaged. How damaged is a combination of how cold it gets, exactly where the plants are, what they are, how big they are etc. It's not black and white, but shades of grey. Last autumn my ivy leaved geraniums survived the first frost with blackening at the edges, but were ok once I brought them in.

On the other hand, crowding plants very close together isn't going to be good for them either. If I were you (please don't blame me if you end up losing some plants!) I'd put outside some of the largest ones to make room in the greenhouse and watch the temperature and weather forecast each night. Put them in a sheltered part of the garden, not in a hollow and not where they get the morning sun. If there's a chance of frost, take them back in to the greenhouse. You would probably get away with covering them with horticultural fleece anyhow if a frost did occur - I've done this successfully in the past. It's a question of spreading the risk really and the risk is real if relatively small.

As I said though in my experience the biggest "threat" is not from frost, but from still commonly cooler temperatures, wind and wet on small not fully hardened plants.


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