Roses can grow very well in clay soil that has been amended with plenty of organic material. Clay soil contains a high concentration of minerals and nutrients that will benefit roses. In heavy clay, the addition of mulch is imperative to ease soil compaction and to increase draining so that the rose’s roots don’t become waterlogged.
Potential Problems for Roses in Clay Soil
The good news is that clay soil is very fertile and contains more calcium, potassium and magnesium than other soil types, all of which are important nutrients for growing healthy, strong roses that are resistant to disease and pest damage.
However, there are a few drawbacks to clay soil that you need to be aware of before planting roses…
- The main drawback of clay soil is that it is less porous than most other soils which will slow water drainage in your garden. This can lead to puddling and water-logged areas, for prolonged periods, particularly after heavy rainfall.
- Roses do require a lot of water, however, they need well-draining soil as the roots are susceptible to root rot when in saturated soil which will kill the plant.
- Clay is also susceptible to compaction if you walk on the beds frequently to do the weeding or till the area with a rotavator. This can exacerbate drainage problems and make it difficult for the roots of your rose to penetrate the soil for stability and to access water and nutrients.
- Whilst clay soils can be acidic they do more often tend to be alkaline. It is always a good idea to check the pH of your soil with an inexpensive soil testing kit from Amazon before you spend your money on expensive plants that may require different conditions.
The way to overcome these problems is by amending your soil to achieve the correct texture, pH, drainage and nutrients that will ensure your rose has the best blooms possible.
How to Amend Clay Soil Before Planting Roses
If the area where you intend on planting your rose is noticeably slow draining then I always recommend that you dig the hole ready for your new rose significantly deeper and wider than the root ball of the rose, ideally about 2-3 three times the volume.
Once your hole is dug to the appropriate size you need to surround the roots of your new rose with organic material. Leaf mould, well-rotted horse manure or compost made from grass clippings, leaves and kitchen scraps is perfect.
The organic material will continue to break down into the soil and loosen the texture of the surrounding clay. This will make the soil more porous and allow water to reach the roots and the excess water can drain away so the roots don’t have to sit in stagnant water.
Organic material will absorb water so that the roots can draw upon that water when it needs to in drier weather but it will also develop a structure that lets excess water drain away.
In particularly heavy clay I do recommend adding sand or grit to your compost mix with about 1 third sand to 2 thirds compost. It is important to mix the sand or grit into the compost mix before planting so that it is evenly distributed and forms the perfect structure for improved drainage.
Once you have your rose positioned in the hole, fill it in with more organic material and your mix of sand and add a surface mulch of 2-3 inches around the base of your rose. Make sure that the mulch is not in contact with the rose wood as prolonged exposure to moisture can rot the wood, so it’s best to give the mulch a 2-inch berth around the main rose cane.
Adding all this organic material will reinvigorate the beneficial ecosystem of the soil. Microbes, yeast, fungus and earthworms all work to break down organic material so that the nutrients are available for the rose to absorb.
Earthworms in particular will help integrate the organic material into the clay soil and chelate the soil into a more fertile form to benefit the rose. Earthworms also create channels in the soil which promotes the infiltration of water, and air and creates space for roots to grow in the heavy clay soil.
Another incentive to continually top up your rose bed with surface mulch is that it will counteract alkaline soils. Compost tends to be pH neutral, if not slightly acidic. Roses love a soil pH in the range of 6 (slightly acidic) to 7 (neutral). Again it is a good idea to test the pH of the soil in your rose bed as an alkaline soil will kill roses.
I recommend applying organic mulch (usually leaf mould or compost) to rose beds with clay soil…
- Once at the start of the season for additional nutrients to promote growth.
- Again in the height of summer when the sun is beating down on the soil. Clay soils have a tendency to dry up and bake hard to form a less permeable texture. Add your mulch during the summer when the sun is at its strongest to help water infiltrate and reach your rose’s roots where it is needed, rather than water running off the surface.
- It is always a good idea to pile on the mulch for a third time in the winter as this will insulate the roots from the worst of the winter cold and give your rose a head start when the weather warms up again in the following spring.
There is no need to dig the mulch or compost into the ground as this will unnecessarily disturb the soil’s ecosystem and potentially cause damage to the roots. The earthworms will pull down organic material into the ground for feeding, so put down the spade and let them do the digging for you!
Top tip: Whilst wood ash, contains a good concentration of potash (which promotes health growth and increases resistance to disease), you do need to be careful not to add too much a once. Wood ash is usually slightly alkaline, so too much will be detrimental to your rose. Scatter approximately one cup of wood ash around the base of your rose early in the growing season and water in. Potash is water soluble so the nutrient will wash into the soil and reach the roots quickly.
Roses for Clay Soil
As long as you have amended your soil with organic matter and ensured that rainfall can infiltrate without forming puddles on the surface then you will be able to grow any rose variety you like thanks to clay soils favourable natural fertility.
Just be aware that all roses need to be in a spot with about 6 hours of direct sunlight per day and they prefer the morning sun.
My personal favourite for clay soils is ‘Rosa Peace’. This is a beautiful rose with cream colour central petals that fade out to an elegant crimson pink.
Rosa Peace is a hardy, relatively disease-resistant rose with a strong bloom and a sweet fragrance that will grow well in clay soils.
The best time of year to plant a new rose is in the late autumn when the plant is dormant but you can plant a rose successfully at any time of year provided you have the right conditions.
Watering Roses in Clay Soil
Clay soils are naturally more forgiving when it comes to watering because of their ability to hold water. If there is more than an inch of rain in the week and the soil is moist then you won’t need to water your rose bushes so as to avoid the soil becoming water-logged.
To check how much rainfall there is in the space of 7 days I recommend that you buy an inexpensive rain gauge to keep track of the weather, so you can water your rose accordingly.
There is also less of a need to regularly water roses that are in humid climates due to the lower rate of evaporation from the soil and lower rate of transpiration from the leaves.
As discussed, strong sunshine can bake clay soils to the point where water will simply run off them and not reach the roots of your rose. If the soil is dry and hard to the touch, add some compost around the base of the rose and then give it a long, slow soak.
The compost will retain the water and encourage it to soak into the soil rather than running off and down into cracks.
In persistently dry weather, it is best practice to give your rose one good soak per week with plenty of water rather than watering a little bit every day.
Bear in mind that in the hottest weather, roses go into a state of semi-dormancy in order to conserve resources where growth slows and fewer blooms are produced. This is perfectly normal and can happen in any rose garden. Roses will perk back up again when the weather cools.
Fertilizer for Roses in clay soil
Fertilizing roses in clay soil is no different to fertilizing roses in any other soil.
If you choose to fertilize your roses organically then I recommend alternating between fish emulsion, bone meal and alfalfa. Roses (like humans) do best with a balanced diet so by switching through these three fertilisers your roses receive the right variety of nutrients that they need to thrive.
Apply fertilizer once per month (starting in April, just before the leave has fully opened) throughout the spring and summer and do not apply any more after August 15th.
Fertilizing promotes new soft growth which will not have time to mature and harden before winter if you apply fertilizer too late. Your rose needs time to prepare for its phase of winter dormancy and any new, late growth will be damaged by frost so make sure you stick to your schedule.
Alternatively, you can apply a pre-made rose formula. These products tend to come in granule form and all you need to do is scatter it around the base of your rose once in the spring before the flowers emerge and again in the height of the summer.
This is a great low maintenance option and miracle-gro rose formula contains all the right nutrients at the right concentration, that your rose needs to produce blooms and thrive.
Conclusion
Clay soils tend to be good for growing roses as they are naturally fertile and are less likely to dry out. However, drainage of excess water can be a problem as clay is not naturally very porous.
The regular addition of mulch and soil amendments helps to improve the structure of clay soils so that the roots can penetrate more easily and excess water can drain away from the roots.
You need to be careful in the summer as clay has a propensity to bake hard which makes it difficult for water to infiltrate the soil and reach the roots. Mulch comprised of leaf mould or compost is the best material to help soften the surface of the soil and encourage the water to drain down and reach the roots.