By Patricia Jordan
I am always being asked why some trees don’t bear fruit. Recently someone asked why their almond tree, which was very mature and usually flowered profusely, often yielded no nuts at all nowadays. Sometimes trees are loaded down with fruits or nuts one year and have few if any the next year. Some are like our mulberry, which has been in the ground for 10 years and has never borne a fruit. It could be the age of the tree, past fruit bearing, or there are other reasons for non-fruiting.
For fertilisation it is usually necessary to have a male tree as well as a female tree in the orchard in order to have fruits. Sometimes the tree has both male and female parts, and is known as hermaphrodite. Pecans are a good example of this with tiny female flowers and long, pollen-laden male tassels on the same branches. In some cases, insects are necessary for fertilisation, as they flit from flower to flower, transferring pollen from one to another as they do so. This method may also be followed by human hands, with the aid of a fine-haired paintbrush, but this is generally only performed in greenhouses, where there may be a lack of insects or wind. Wind pollination is normal in plants with tassels such as pecans, casuarinas and sweetcorn, to name just a few. The pollen is transferred from the tassel into the flower by breezes, resulting in fruit, corncobs or little nuts in the case of casuarina trees.
Once the flowers have been fertilised they begin to produce the fruit. Early winds and heavy rain can cause the embryonic fruit to fall, as can cold nights and hot weather out of season. Some say that flowering almond trees are a sign of spring as they come into flower very early here, and while we enjoy looking at their lovely flowers there may not be many bees around to fertilise them. Even if they have been fertilised, strong spring winds and rain, as we had in mid February, can devastate the tree scattering the flowers all around, with the result there will be no nuts.
The stress of having a huge crop can also cause the tree not to produce many flowers in the next season. If your tree has a lot of little fruit early on, reduce the numbers as they begin to swell, only retaining the strongest looking fruit, as you would with loquats. Sometimes, this occurs naturally and is known around the world as the ‘June Drop’, although it doesn’t always happen in June!
We can’t control the wind and rain any more than we can turn down the heat during the extremely unseasonal hot weather in April that we have endured over the last three or so years. At this time of the year, embryonic fruit on the trees cannot cope with such extremes of weather, and consequently they are burned and fall to the ground!
WHAT TO DO IN THE GARDEN THIS MONTH
March is one of my favourite months here. We can look forward to better weather, warmer temperatures and lengthening days. Of course, March can be very windy with cold nights and it is not a good idea to plant any delicate plants out just yet. Someone else once likened it to the ‘Month of Expectation’ and I like that description, after winter it is always exciting to look forward to seeing new plants flowering for the first time and waiting for old favourites to pop up through the earth! All the hard work of pruning and dividing plants during the really cold and wet months will pay dividends now. As the sap rises, leaf buds swell and flowers burst out of their sepals. The earliest of the bulbs are over and need to have their dead flowers removed, so that they can rebuild their strength for next season, but there are plenty more like freesias to take their place in the flowerbeds and pots. A very pretty bulb that grows well in a pot, and eminently suitable for those who garden on verandas, is Hippeastrum, known here and other places, as Amaryllis. Once planted (with their shoulders proud of the soil) they grow at an alarming rate, the flower stem first with a huge bud on the top. You may need to give the plant some support because of the weight of the flower or it will topple over. They certainly are showstoppers in all their vibrant colours.
‘Dutch Iris’, Iris ziphium’, whose foliage has been above ground for quite some time, will be sending up flowering stems now with white, blue or yellow flowers. Iris albicans grows from a rhizome and is the first of the herbaceous irises to flower. The delicate white flowers with golden throats were discovered around Moslem graves in Arabia. Following them come the tall, slender blue irises, Iris germanica, which love our growing conditions here. They are best planted at the back of a border or in the centre of an all-round bed, giving height and interest with their rhizomes pointing towards the sun, so that they will be baked and produce lots of flowers each year.
There are lots of jobs to be getting on with this month including regular feeding of roses and other flowers and there are various proprietary rose foods on the market. Fertilisers are often available in a soluble form, which can be watered on, or in granules that you fork in around the roots.
When annual seedlings like nigella, poppies and cosmos appear, thin them out so that the remainder have room to grow. This applies to vegetables and salad crops as well. Once all danger of low night temperatures is past, then you can plant out sweetcorn, which should grow well this season, as the soil is wet deep down. If you use the same area for veggies all the time, give it a rest for a few weeks before you plant anything else, and rotate your crops so that you don’t grow the same thing in the same space every season. The break between seasons is a good time to dig in the contents of your compost bins as well, as it is much better for you and your family than using artificial fertilisers.
You should be able to pot on any cuttings you have taken from now on. Check the bottom of the pots to see if there are any white fibrous roots appearing through the holes, which means that they are ready to move up a pot. Gradually introduce them to the outside world, as they are still quite vulnerable at this stage.
Pecans may need a dose of zinc chelate at this time. The dosage is two dessertspoons in ten litres of water, watered into the ground about 30cm away from the trunk. Keep watching out for greenflies, blackflies and brown flies on any new foliage. Spray with a soapy solution or run your fingers up and down the stems to get rid of them. Roses also suffer from greenfly and the same remedy can be used for them, but watch out for the thorns!
Plant of the Month Canna Lilies
Without exception, all Canna lilies introduced into Europe can be traced back to the Americas. They are tropical and subtropical flowering plants with large, banana-like leaves. As a result of much hybridising, there are hundreds of cannas to choose from, although there are only a few available here. Many have large, showy flowers of red, yellow or orange with green or variegated leaves, Canna ‘Durban’ is a good example of this. These plants grow from rhizomes, and should be divided up every three or four years. They like plenty of heat, so grow them in full sun in the garden or in pots, but they can also tolerate partial shade. You may see them growing in huge clumps in village gardens here.
Feeding them with a monthly liquid feed with a high potassium content (last number on the box) will ensure continual flowering and deadhead as the flowers die off. Cannas have been much hybridised, so any seeds will be sterile.
Cannas are not often bothered by disease, as their leaves are covered with a waxy substance, so water is repelled and fungus doesn’t usually take hold. Grasshoppers can hide in the new furled leaves though and chomp their way through the them, leaving unsightly holes, so watch out for them and deal with them by unfurling the leaves and removing them.