We are in the depths of winter so I thought I would look ahead to the flowers of summer and focus on roses for a few days. It is not just wishful thinking because now is the time to plant bare-root roses from specialists and only a few months away from pruning time. I like to buy roses by mail order rather than from garden centres because bare-root roses get away better than potted roses and it is good to support specialist growers which will offer the widest range of varieties and the most modern varieties. Potted roses, bought in spring will be field-grown roses, just potted up, with their roots cut back to fit in the pots while later in the season potted roses can be bought with leaves and flowers on. This is a nice way to buy them, especially as a gift, but roses are hungry but have lazy roots and I firmly believe it is better to buy bare-root roses and spread out the roots in the soil, which you cannot do with potted roses. More importantly, not every garden centre looks after their roses well in summer and it is not unusual to see diseased and hungry roses for sale after the spring rush. Planning ahead and buying good roses in winter is the best plan.
Roses are, with a few exceptions, not grown from cuttings but are grafted. More precisely they are ‘budded’ which means that a bud from the desired variety is placed on a rootstock, above ground level in summer when the green bark of the stock can be cut, lifted and peeled back and the bud slid under it. The bud soon grows and later the rootstock is cut back and ‘voila’, there is a new rose bush. The advantage of this method is that a large number of plants can be produced from the ‘scion wood’ – the desirable variety. Although roses can be grown from cuttings, you get far more plants of the variety by using just one bud from the scion wood to produce a new bush than using the whole length of stem to get one plant. You can see a row of budded roses below with the grey foliage of the rootstocks and new growth with flowers of the scions.
Before I get on to the pretty pictures, a couple of oddities. I will not go on about mildew or black spot or rust because, common though these are, they can be controlled by spraying with many fungicides. These will control these diseases but they have to be used as a preventative measure – they will not make existing symptoms disappear. You need to apply them early and regularly throughout the season on vulnerable varieties. Bear in mind that many modern roses, and especially those selected (in the UK) as Rose of the Year (ROTY), are usually more or less free from disease. But the problem below is balling, something that affects roses but is not a disease. It occurs on some varieties more than others, especially those with fully double flowers. The outer petals stick together, either because of wet, cool weather or sometimes because sun scorches them, and then the bud cannot open and if the weather is cool grey mould can set in. Though not practical over the whole garden, if you cut these blooms and peel off the outer petals they will last in the vase as long as they have not been in this form for too long because the inner parts of the flower continue to develop and if they are old the flowers can just fall apart. In wet weather it is best to remove affected flowers just to control the spread of grey mould.
A much less common problem is to find a robin’s pincushion. These strange growths are found on garden roses and more commonly wild roses, and are caused by an insect. The tiny gall wasp ( Diplolepis rosae) lays eggs in the plant and the rose responds by forming a furry gall to contain the grubs that feed on the tissue. Little damage is done to the plants and seeing these growths is a bit of a treat. They are usually tinted with red, especially as they age, but they can also be green. They are not always at the ends of the shoot.
Of similar colouring, and looking superficially similar are the flowers of Rosa chinensis ‘Viridiflora’ which is an unusual rose. A rather weak growing and spindly plant, it has blooms that are composed wholly of sepals and open pale green but develop red colouring as they age. Not surprisingly, they have no scent and are for lovers of the curious rather than for anyone that wants a showy border!
The rose at the top is ‘Crazy for You’, sold as ‘Fourth of July’ in the USA and will be featured in the coming days.