How to graft roses: the shield grafting technique.

Why graft a rose bush?

Just like some varieties of fruit trees or vegetable plants, modern horticultural or hybrid roses (man-made) can be obtained by grafting. This is a propagation technique resulting from joining two parts. It requires a scion to provide the aerial part, and a rootstock to form the root system.

Grafting roses offers certain advantages.

• The plant combines the qualities of the rootstock and the scion. The rootstock often has good vigour, provides tolerance to certain diseases (notably cryptogamic diseases), to a particular soil type (calcareous or sandy, for example), or to a climate (resistance to drought, humidity, frosts), etc. It is often of wild origin. Its role is to allow the scion to feed by drawing from the soil the water and minerals necessary for its growth. For its part, the scion provides its ornamental qualities (foliage, flowering, fragrance, fruiting).
• It is a more reliable method of multiplication than sowing, which allows faithful reproduction of a plant’s genetic material, and thus an identical rose variety. Grafting also has a higher success rate and greater stability than propagation by cuttings.
• It enables rose varieties with a distinctive habit, not found in nature, such as stem roses or weeping roses.

For more information: Why are roses grafted?

Note that grafting also has some drawbacks. Grafted roses generally have a shorter lifespan. It is also a technique that does not favour natural genetic variation (evolution), thereby making roses less adaptable, particularly in the face of disease.

Grafting enables stem roses

The different rootstocks for roses

There are different types of rootstocks for roses, each with its own advantages and disadvantages.

• Rosa canina, or the dog rose, is one of the most common rootstocks, which has long been the only one used for the propagation of roses. It is a native plant, growing wild in our territory. Rosa canina has good vigour, great hardiness, tolerance to a wide range of soils (except acidic soils) and good resistance to diseases. It is an easy rose to grow, used for grafting varieties with large flowers, hybrid teas, Floribunda roses or climbing roses. However, it tolerates drought poorly, requires a sunny exposure and tends to sucker a lot (it spreads by producing suckers).
• Rosa laxa is the rootstock used for its tolerance to calcareous soils, where most roses would struggle under these growing conditions. It also provides good tolerance to cold and drought. Rosa laxa is used for grafting shrub roses, climbing roses and some hybrid teas. As for its weaknesses, it can be more susceptible to certain fungal diseases (powdery mildew in particular).
• Rosa multiflora provides good vigour and a well-branched habit (comprising numerous ramified shoots giving a dense appearance). Fairly hardy, it tolerates acidic soils, drought, frost and is not very susceptible to powdery mildew (powdery mildew). This rootstock is widely used for pot-grown roses, giving them a stocky silhouette. Its lifespan is shorter and the flower colours are less vibrant.
• Rosa rugosa is the ideal rootstock for gardens with damp soil. It withstands cold, salt spray and sandy soils. It is also a relatively disease-resistant species. Conversely, it does not like drought and tends to sucker.

To choose a rootstock wisely, consider:

• the cultivation specifics expected (soil and climate constraints, use, garden type);
• its compatibility with the scion;
• its vigour, according to the desired adult habit.

Rosa canina is the rootstock most frequently used

When is the best time to graft a rose?

Grafting roses is carried out from mid-summer to the end of summer, in dry weather, i.e., between mid-July and mid-September. It is a dormant-eye graft (the eye will not develop until the following spring).

A growing-eye graft is possible, carried out in late spring (between May and June).

Shield grafting technique

Grafting is a technique that can be delicate and not always easy for a novice gardener.

For grafting, an eye bud from the variety to be propagated will be inserted into the tissues of the rootstock. The above-ground parts of the rootstock will then be cut back to allow the scion to develop. Let’s look at, in practice, how to graft a rose.

Before grafting

First, obtain the desired rootstock and scion.

The rootstock should be planted several months before grafting, at the latest in early spring of the preceding year, to allow it to establish and develop its root system. Be sure to water the soil in the days leading up to grafting.

Equipment, plan for:

• a clean pair of pruning shears;
• a grafting knife well sharpened and pre-disinfected (or, if unavailable, a cutter);
• ties (raffia, wool twine, grafting tape) or a suitable dressing.

Step-by-step grafting

Shield grafting, or shield budding, is the easiest grafting technique to perform.

1- Select a mature shoot from the scion (having grown the previous year and having already flowered), measuring about 1 cm in diameter. Choose a healthy shoot, free from disease. Using a grafting knife well sharpened and pre-disinfected, cut a fragment of shoots to two-thirds of its length from the lower end. Remove the spines and the leaves, but keep the petioles (the part linking the lamina to the stem). Place the sample out of direct sun, perhaps in a damp cloth.

2- Choose an eye (bud developing) well formed. Make two incisions on the shoot with the grafting knife: this is what we call shield bud taking. The first incision will be made about 1 to 2 cm above a bud, the second below. Then gently lift the bark without penetrating the wood. Remove any wood fragments.

3- Choose a straight, healthy shoot on the rootstock. Clean the area that will receive the shield bud from the scion, removing spines, leaves and rootlets from about 10 cm above the collar (the junction between the roots and the stem). This is then a root graft. To obtain a standard rose, perform a top graft (higher up on the shoot). Make a T-cut in the bark of the rootstock : a horizontal cut about 2 cm long, then a vertical cut about 3 cm long.