Roddy Llewellyn's gardening advice

PUBLISHED: 11:19 17 May 2011 | UPDATED: 19:23 20 February 2013

Roddy Llewellyn's gardening advice

Roddy Llewellyn's gardening advice

Roddy Llewellyn sings the praises of the tender geranium


Commoner puts on a grand show

Roddy Llewellyn sings the praises of the tender geranium

There has always been a feeling of ambivalence by many gardeners when it comes to tender geraniums, commonly named zonal pelargoniums, used as summer bedding. Not to be confused with hardy geraniums or perennial cranesbills, those useful ground-cover plants for the front of the border, tender geraniums are often dismissed as too commonplace to entertain, and this is a pity. This is probably because they fell out of fashion after World War Two, at a time when many Victorian values were rejected and they have never regained popularity since. The fact of the matter is that they offer very good value for money in that they are quite capable of flowering for most of the year. What puts many people off, I think, is that they are popularly grown in public places where, especially in later summer, they are not regularly deadheaded, and this results in a messy show.

The same plants can last you for many years with a few simple rules to follow. The advantage of buying a plant in flower means that you know exactly what youre getting and this is the time to do so from the vast array available at comprehensive garden centres. They can be planted outside during early June in the South and mid-June in the North, i.e. once the danger of frost is over. They are just as well suited out in the border as they are in a container so long as they are exposed to as much sunlight as possible. This is because the majority of tender geraniums originally hail from The Cape Province in South Africa. Those destined for containers are perfectly happy growing in a soil consisting of 50 per cent potting compost and 50 per cent bagged soil so long as good-drainage is assured. When planted outside they will like you all the more if you mix the same in with your garden soil. In either case, they do much better if given a liquid feed very two weeks or so using something similar to a tomato feed.

Perhaps their greatest strength is that they are tolerant of dry air, something that most houseplants are not, and this is why they will remain perfectly happy while they are sitting on a sunny window sill during the winter after having been brought indoors in September before the first frosts. They will be happier of course, in a heated greenhouse or conservatory where there is a degree of humidity where they will continue to flower better during the gloomiest months so long as they are never overwatered, indeed they enjoy periods of being kept bone dry for small periods. The same plants can last you for years although tip cuttings can be taken anytime during summer to give you younger, more vigorous plants.

Variegated plants have an annoying habit of reverting, i.e. producing shoots bearing green leaves. One such plant is the beautiful variegated Norway maple (Acer platanoides drummondii). On a long journey by road I always see such reverting specimens and I long to jump out of the car with a saw and cut them off. The best way to do this is to cut or saw off branches right down to the point where they start to bear green leaves as soon as you are able. You may need a ladder. The trouble is, is that if you leave them, the more vigorous green leaf-bearing branches will slowly take over and eventually you will be left with a tree with plain green leaves, thus spoiling the whole point of the exercise.

April proved to be a sizzler with hardly a drop of rain in many areas and as a result, spring-flowering shrubs (and bulbs) had a disappointingly short season and then put on much more growth than is normal for this time of year. June is normally the time to give the likes of kolkwitzia, weigela and philadelphus a good haircut and so there is no time to be lost. Now that herbs are growing hard and fast now is the time to pick them for drying or freezing for winter use. My rosemary is not looking very happy after last winter, and so I intend taking cuttings from it this month so that I can keep some plants safe under glass this coming winter. It is now safe to plant out your dahlias. What a tragedy it was that we lost so many tubers during the winter when they succumbed to freezing temperatures in places that had proved safe from frost over the last decade or so.


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