Blog – Page 52 – Gardener Report

Yes you can grow roses successfully in rocky soils. Rocky soil tends to be poor in nutrients and drains too quickly for roses to draw up water so its necessary to make some amendments to the soil before planting. This includes adding plenty of organic matter to retain water, add nutrients and improve the soil structure. Roses are a lot more hardy then people think and they can grow in a variety of soil conditions. As long as you make some adjustments and care for them in the proper way roses can grow healthy and produce flowers in rocky soils. In this article we will look at: How to prepare rocky rock for planting roses. Why it is so important to add regular mulch on rocky soils. How much and when you should water roses on rocky soil. How to fertilize roses in rock soil. How to Prepare Rocky Soil for Rose Planting 1. Dig a hole that is roughly twice the size of the root ball of your rose. This is to allow you more space to add organic material to the hole to help the soil retain more water and improve the soil structure so that the roots can grow through the soil properly. The hole needs to be twice the depth and well as width of the root ball so that you can layer the bottom of the hole with organic matter. Rose roots do like well draining soil but the problem with rocky soil is that it drains too fast for the roots to draw up moisture. Organic matter such as compost or leaf mould has a far greater capacity to hold onto moisture so that the root can draw upon this water when they need to. Organic matter breaks down into a structure that allows excess water to drain away, which is the perfect balance for roses. 2. Place the rose in the hole at the desired angle (Ideally with the most foliage facing the sun) and make sure that the bud union (the point at which the rose canes are attached the roots) will be under the soil line once the hole is filled in. The bud union should an inch underground so that the rose bush remains stable before the roots have a chance to establish and anchor themselves in. 3. Discard the rocky soil from your hole and fill in the rest of the space around the rose with organic matter. This can be leaf mould, well rotted horse manure, compost or a combination of all three. Leaf mould in particular has a high capacity to hold water to combat the naturally dry, rocky soil. Horse manure and compost are also highly fertile and will encourage worm activity as well as feed the overall soil ecosystem. Worms digest the organic matter and produce worm casts, which concentrate nutrients and minerals in a form that is easier for the roots to absorb as well as regulate the pH of the soil. Healthier soil produces healthier more disease resistant roses with strong, plentiful blooms. 3. Firm in the soil around the base of the rose to keep the rose bush stable, ensuring that the bud union is below soil level. This is a really important step, so make sure you really heel in the soil around the base of the rose. Rocky soils make it harder for roots to establish so providing stability is essential. 4. Once the rose is in the ground you can give it a good long soak with the soaker hose with at least four gallons of water. Watering Roses in Rocky Soil Rocky soils do not retain water very well and rain can drain away too quickly for the roots to absorb the moisture, leading to dehydrated plant with wilting, yellow leaves. This is why adding mulch and amending the soil before you plant the rose is essential. Organic matter holds onto water far better and creates the ideal soil structure the roots of the rose to grow deep so they can draw moisture and find nutrients. You need to water each rose bush once a week in the growing season with a good long soak. Roses prefer one good soaking per week rather then a little and often watering schedule. You can do this by watering slowly with a soaker hose, which gives the water time to absorb into the soil and not run off the surface, or of course by watering with a 4 gallon watering can. This may seem excessive but I assure you roses really do love a generous soak of at least 4 gallons even in temperate climates. You may need to increase the frequency of your watering schedule to twice a week if the weather is particularly, hot, dry or windy. Windy weather can sap moisture from the ground and increase transpiration form the rose’s leaves, so consider providing a wind break from your rose with other vegetation such as conifer trees or a nearby fence. If you are in a particularly windy location then the best rose variety for you will be a regosa rose. These roses are the hardiest of them all. They’re disease resistant, grow in a variety of soil conditions and can even tolerate salt spray which useful if you are by the coast, not to mention they produce beautiful red blooms with a wonderfully sweet fragrance. The Importance of Adding Mulch to Roses in Rocky Soils It is worth reemphasising the importance of regularly applying mulch around your roses on the surface of rocky soils, particularly in the height of summer. In the warmer weather, intense sunshine can bake rocky soils into a hard crust. This hard crust can cause the rain and water from the hose to simply run off the surface without absorbing into the soil and reaching the roots of your rose and cause the plant to wilt. If you add a thick 2 inch layer of compost of leaf mould on top of the surface of the soil around the base of the rose, this will encourage the water to infiltrate into the soil so it goes where it is needed. Also the mulch does not harden in the sun in the same way that rocky or clay soils do, but instead retains a softer texture and thus retains more water and improves the soil structure for both good drainage and better root growth. The roots also benefit from being kept cool by the mulch, as excessive heat can damage rose roots. Rocky soils tend to be poor in nutrients so mulching is paramount to add fertility and to fuel the soils ecosystem so that you have strong, healthy roses with plentiful blooms. Apply a two inch layer of mulch around your roses twice a year in rocky soils: The first application should be at the start of spring to encourage new growth, keep the roots cool and to hold moisture. Layer 2 inches around the base of the rose but keep the mulch 3 inches away from your rose canes as they do not like to be exposed to moisture for prolonged periods. Apply the second layer in around September or October to insulate the roots from the worst of the winter cold. It’s thought that well insulated roots are able to repair themselves and grow over winter. Also this will give your rose a head for next years growing season. In particularly dry areas I tend to favour leaf mould as my mulch of choice however I think the optimal mulch for rocky soil is a mix of leaf mould, compost (from general garden waste) and well rotted horse manure composed of a third of each. With these three types you have all your bases covered in terms of water retention, soil structure and of course adding fertility to the soil. Horse manure is particular good for enriching soil as it is packed with nutrients and the earth worms love it and repay you by providing the rose with highly fertile worm castings. Fertilizer for Roses in Rocky Soil An important part of successfully growing roses (with as many flowers as possible) is to add fertilizer as rocky soils are relatively low in nutrients compared to other soils. Applying mulch will always add fertility but roses are heavy feeders so the addition of fertilizer is a welcome helping hand. In terms of organic fertilizer, bone meal, fish emulsion and alfalfa are all good sources of nutrients for your roses. I like to use alfalfa to feed the soil and a dedicated rose fertilizer such as miracle grow rose and shrub. I would recommend using a specific rose supplement as it has a balance of all the nutrients and minerals that your rose needs, in the right concentration to grow strong and produce beautiful flowers which will compensate for the poor fertility of rocky soil. All you need to do is scatter the granules over the soil twice a year; once at the start of the growing season and once in the middle of summer. You should not add any fertilizer to your shrub after the 15th of August as the nitrogen in the fertilizer will promote new soft growth that is susceptible too cold weather and frost damage and it will turn black in winter. Another incentive to add fertilizer is that your rose will grow stronger and more resistant to common rose diseases and pests such as black spot. Conclusion In summary it is possible to grow roses in rocky soil if you make the correct soil amendments and some adjustments to suit the growing conditions of roses. They key to growing roses in rocky soils is to be generous with your mulch application as this will be improve the soil and retain more water so your rose does not become dehydrated in the hottest months of the years. Fertilizer is also key as rocky soils tend to be nutrient poor. Remember to water your roses with a 4 gallon soak once per week and check moisture levels of the soil in the summer. If the soil is dry at a fingers depth then do not hesitate to increase the frequency of your watering to twice a week to keep the rose healthy and hydrated.