Roses that are not blooming is usually because of too much nitrogen fertilizer. Excess nitrogen promotes foliage growth at the expense of flowers resulting in leggy growth with no blooms. Pests, lack of light and pruning at the wrong time of year can all cause rose bushes not to bloom.
I have listed each cause for roses, displaying fewer flowers or not blooming at all, in the order of the most likely reason.
Most common reasons for roses not blooming:
- Using too much fertilizer or applying too frequently.
- Nutrient poor soil.
- Pests such as aphids that extract sap for the developing flower buds.
- Too much shade (roses bloom to their best in full sun of at least 6 hours).
- Not pruning the rose annually (rose has turned woody with few blooms).
- Pruning roses at the wrong time of year (some varieties only flower on last years growth therefore pruning in the Spring can prevent the rose from flowering) .
Keep reading for how to why your rose is not blooming and how to implement the solution so that your rose blooms the following Spring…
1. Too Much Nitrogen (Scale back the Fertilizer)
Perhaps the most common reason for roses not blooming properly or to their full potential is because of too much nitrogen as a result of high strength or high frequency use of a fertilizer.
All plants require Nitrogen, Phosphorous and Potassium (NPK) to grow well, however an over abundance of nitrogen in the soil can promote foliage growth at the expense of flowers.
The increased amount of nitrogen causes the stems, branches and leaves of your roses to become sappy and droop as a sign of stress. (Yellow leaves are also a sign of too much nitrogen).
The excessive new growth is more susceptible to pests, diseases and frost damage, which is why it is so important to use the appropriate amount of fertilizer for rose bushes.
Personally I recommend using a product specifically made for roses which contains the correct balance of nutrients for roses to grow and flower and takes the guess work and risk away from fertilizing with a more generic product.
If your rose has plentiful foliage and few flowers due to over fertilizing then it is important to scale back the use of fertilizer and prune back any drooping growth, particularly if the leaves have turned yellow.
Established roses are usually quite resilient so there is every prospect of the rose bush recovering the following season and displaying flowers if you adjust the amount of fertilizer you use on the rose to a more appropriate level by following the manufacturers instructions.
2. Nutrient Poor Soil
Sandy or stony soils do not retain much moisture or nutrients which can restrict the amount of resources for the roots to absorb. This results in a sickly looking rose with poor growth and few if any blooms in the Summer.
How to Solve it…
Roses can grow and bloom in sandy or stony soils if there has been good soil preparation before planting.
Good soil preparation for roses includes:
- Amending the planting area with lots of organic matter before planting. Compost, leaf mould and well rotted manure are all excellent for retaining moisture and contributing nutrients to the soil.
- Distributing a 1 inch layer of mulch around the rose to conserve moisture, simulate the soils beneficial ecosystem, contribute nutrients to the soil and improve the soil structure to suit the roses.
If your rose is already planted and established in somewhat sandy or stony soil and it is not practical to transplant the rose then you can either try to lever the rose temporarily out the ground with a fork and some careful digging and remove some of the sandy or stony soil to amend it with compost.
Or simply apply mulch frequently and be diligent about the use of fertilizer to counter act the lack of nutrients in the soil.
Apply mulch at the start of spring to help to conserve water through Summer and at the end of Fall to insulate the roots from freezing temperatures in the Winter.
Applications of mulch over time have a profound effect on the soils nutrient density and really help to improve the structure of the soil create preferable conditions for roses to be healthy and display an impressive bloom.
The additional nutrients and increased moisture content of the soil for mulching, will stand the rose in good sted to display blooms the following Spring.
3. Pests Attacking the Rose Buds (Aphids)
Another common reason for roses not flowering is because of pests attacking the rose buds as they form.
The most common insect pest that compromises a rose’s blooms is the aphid.
These small green insects feed on the sap of roses and are particularly attracted the the developing buds of rose flowers which is why they are such a problem.
The aphids cause damage to the leaves and flowers which can contort their growth and cause a poor display of flowers.
Most gardens have some level of aphid presence however their population and therefore there potential for damage is usually controlled by predatory insects such as lady bugs.
Aphids are especially problematic for roses that have an excess of nitrogen fertilizer as the nitrogen increases the amount of sap and softens the plants tissue so that the sap is more easily accessible to the aphids.
Save Rose Blooms from Aphids
The key to saving your rose flower buds from being besieged with an aphid attack is with careful monitoring.
If you see the aphids amassing around your rose buds early in the Spring or Summer then you can address the problems before they do an significant damage to your rose blooms.
How to address an infestation of aphids on rose buds:
- Knock the aphids off the rose buds with you hands or with gentle yet assertive some shaking! Once they are on the ground they are easy prey for predatory insects and birds.
- It is possible to blast the aphids off with a hose pipe so long as the pressure is not too strong that it would itself damage the rose.
- Spray the rose targeting the buds with an organic insecticidal soap.
- Encourage a good garden ecosystem with ‘bug hotels’ rather then using chemical pesticide spray which indiscriminately kill beneficial inspects that prey on aphids (such as lady bugs) which naturally control the aphid population.
As you can see from the photo my own rose had a good number of aphids yet I was able to limit the damage by checking my rose in the Spring and removing any aphids by hand.
This is a very effective way to tackle the problem and my Rosa ‘Burgundy Ice‘ was able to display a spectacular bloom that year.
4. Lack of sun (Roses Bloom Best with 6+ hours of Sun)
Roses bloom to their best when planted in full sun (at least 6 hours of sun per day).
Roses that are in too much shade have fewer blooms and a more spindly appearance as the rose grows leggy searching for more light.
The only solutions to this is to transplant the rose to a location of your garden with more sun or perhaps cut back over hanging tree branches that may be casting shade on the rose.
It is best practice to plant roses around three feet apart to ensure the rose has enough light and therefore energy to bloom and to reduce the risk of fungal disease by increasing airflow around the foliage whilst giving you space to move around the rose for pruning and regular deadheading which increases the amount of blooms.
The amount of sunlight is one of the most influential factor for how well rose bushes bloom and important for disease resistance.
(Read my article, choosing the best pots for roses).
5. Lack of Consistent Pruning
Pruning every year is an important aspect of rose maintenance and helps to prevent your rose from becoming too woody with fewer blooms.
Pruning your rose once per year stimulates new growth of stems and branches that support a greater number of blooms as the older, leggy wood can become less productive in terms of displaying flowers.
In addition to annual pruning, regular deadheading is key to promote rose blooms as removing the faded flowers stimulates the rose to produce more flowers rather then direct its energy into producing seeds (rose hips).
If neglected, roses can grow leggy and display fewer flowers. The resulting woody rose is more susceptible to damage in the Winter as the wood can be brittle.
If your rose has not been pruned for a few years it can still be revived with careful pruning to help cut away dead wood, improve the appearance and encourage flowers.
Pruning woody neglected roses requires a visual explanation so here is a YouTube video which demonstrates how to prune neglected roses.
6. When to Prune Your Rose for More Blooms
Knowing when to prune your rose so that it displays flowers is as important as knowing how to prune the rose.
Some rose varieties of rose display their flowers on the previous years growth so if you prune in Spring then you could be removing the developing flowers and the rose cannot bloom until the following year.
For roses that repeat flower, regular dead heading throughout the season and pruning branches in the Winter ensures a tidy rose bush and prevents cutting off any developing flower buds or wood that will host the flowers the following year.
For rose varieties that flower just once in the year carry out the annual prune after the bush has finished flowering in the late summer.
If you have hard pruned your roses in the Spring then you will have to wait to next year to see any flowers.
- The reason for roses not blooming is usually because of too much nitrogen due the frequent use of fertilizer. Nitrogen promotes foliage growth at the expense of blooms so too much fertilizer results in a leggy plant with lots of foliage but few flowers.
- Roses are heavy feeders so nutrient poor sandy or stony soils can be responsible for a lack of blooms. Prepare to soil with lots of compost, leaf mould and well rotted manure, add mulch every Spring and use a fertilizer to provide the rose with the nutrients for blooming.
- Aphids feed on the sap of developing rose buds which distorts the growth and blooms of your rose. The best way to deal with aphids is to check your roses for aphids frequently and remove them for the rose by hand or with water. Aphid numbers are controlled by insect predators such as lady bugs and birds so there are rarely a severe problem in most gardens.
- Sunlight is positively correlated with the number of blooms a rose displays with roses preferring full sun (at least 6 hours per day). Transplant roses that are in the shade to sunnier locations or cut back overhanging tree limbs that are casting shade to ensure your rose displays flowers in the Spring and Summer.
- Prune your rose annually to keep the rose in good health so that it blooms. Regular deadheading can encourage more blooms in repeat flowering varieties.
- Prune roses back after flowering in the Fall or Winter to ensure flower buds can develop and avoid cutting back the previous years growth in the Spring as this can prevent roses from flowering.