Apart from the abundant large flowers, the great thing about these roses is that they are easy to look after. They only need a bit of care. We will guide you through the basics so that you can appreciate the beauty they offer.

Here is what we will cover:

Grandiflora Hardiness 

Grandifloras are a hybrid of the Hybrid Teas and the Floribunda Roses.  They have been bred since the 1950s and just get better with time. Do not expect them to be as hardy as many of the Old Roses but they need little in the way of pampering.

Occasional care and maintenance are all that is needed. Sun and decent airflow help to ward off most problems. Keep an eye on them as pests and diseases can spread from other plants in the garden. The trick is to catch any problems early to prevent a serious issue.

Grandiflora Sun Requirements

If your rose does not get enough sun, it will not produce flowers anywhere near its full potential. Furthermore, it will be more susceptible to diseases. The general rule is 6 hours of sun, as a minimum. Anywhere from 4 to 8 hours of full sun should be enough for most Floribundas but the more, the better.

Some hybrids are more shade-tolerant so make your selection with care.  

Where to Plant Grandiflora

Provided they get enough sun, you can plant them pretty much anywhere. Note that they grow roughly 2 to 6 feet in height and have a spread of about 2 to 4 feet. This will indicate where to position them relative to other plants.

They are perfect container roses so are an excellent choice if you want some potted color.

Also, note that many have a heavenly fragrance so try to position them in areas where you can appreciate this aspect.

Ideal Soil for Grandiflora 

The soil needs to be well-draining and rich in nutrients or organic matter. Loamy soil is great. If the soil is not up to scratch, you can enhance it with compost or manure. A bit of peat moss at the base will help aid drainage. They prefer acidic soil with a pH of around 7.

Watering Grandiflora  

The key to watering is to keep an eye on the temperature and the appearance of the plant. New plants and those in pots need regular watering, about 2 to 3 times a week. When watering established roses, give them a good soaking, with at least 2 inches of water. Avoid wetting the foliage as this can lead to disease.

Water at least twice a week and ensure the soil is dry between watering. In winter, little to no watering is required as the plant is dormant. The exception is, as often happens, you have a sudden warm spell in the winter. In this case, water in the morning in case the cold weather comes back.

Grandiflora Temperature and Humidity

 The perfect temperature for these roses is 70ºF. They are hardy so can handle a fair variation either way. Mulch is always a good idea as it helps to regulate soil temperature. Pine needles work well. It keeps it cool when it is hot and warms it a bit when it is cold. Spread it around the base of the rose but don’t let it touch the stem.

If it gets extremely cold you can use burlap or frost netting to protect them. This is especially important if the roses are young. In extreme heat, shade cloth or net can be positioned above (not touching) the rose bush or bushes. Older roses have toughened up and will probably only need a bit more water than normal in extreme heat.

Fertilizing Grandiflora

 All roses appreciate a fair amount of fertilizer. The repeat blooming habits of the Grandiflora, however, mean that it needs even more nutrients than most if you want the best display. Apart from the dormant winter months, you should fertilize the rose every six weeks or so. The best option is an organic slow-release fertilizer. This can simply be mixed in with the top layer of soil. Always water well after applying fertilizer.

Pruning Your Grandiflora

This is a lot simpler than many people imagine. The goal is to shape the plant and remove any dead parts or scraggly shoots. You also want to deadhead the roses as the blooms are spent. This can done throughout the year.

The main pruning should be done in late winter. Older canes can be cut back to near the base. Other canes can be cut to roughly 4 to 6 buds from the base. This will allow for a good shape and let in air and light. Once the temperatures rise the rose will be ready for action.

Grandiflora Pests and How to Treat Them

There are several pests to watch out for. Fortunately, nature often takes care of the problem; if not, they are normally easy to treat.  

• Aphids

These are normally small green, pink, or white insects. While they are tiny they form clusters making them easier to see. Aphids suck the sap from the rose and will reduce performance if the problem is severe. They also make the plant unsightly.  

Natural predators such as ladybugs and wasps often take care of aphids. If the infestation becomes large you need to take action. A powerful jet of water often does the trick although it might need to be done several times. It is free, safe, and eco-friendly. Repeat the process and keep a close eye on the situation.  If that does not work, you can spray the pests with insecticidal soap. Try to avoid chemicals if possible as they will also harm the natural predators.

• Beetles

The most common beetle found on roses is the Japanese Beetle. These destructive critters will chomp through the leaves, buds, and flowers rapidly. The evidence of their destruction is easy to identify. They are day feeders and have a green body with brown wings.

You will rarely see most other beetles they feed at night. All you will see is the result of their feast.

You can remove beetles by hand and destroy them in soapy water. There are also beetle traps that can be used but be sure to follow the instructions as you risk making the problem worse.  There are various other commercial applications that you can consider if all else fails. Neem oil is a popular option.

Grandiflora Disease and How to Treat Them

A healthy rose will cope with diseases, so prevention is better than cure. Inspect them regularly and cut back any diseased or damaged sections. Always use sharp sterile secateurs. Ensure they get enough airflow and sunlight.

Even with those precautions, you might still encounter the odd problem. Here are the main ones to watch out for:

• Black Spot

This fungal disease is easy to identify and appears on the leaves as black spots, no surprise there. It will stress and weaken the plant if left untreated. It is often caused by moisture accumulating on the leaves, one of the main reasons to only water the base of the rose.

Early identification helps. Remove severely damaged leaves and discard. You can then spray with a mix of water and baking soda (1 teaspoon to one quart of tepid water) or a copper-based fungicidal spray. Neem oil can also be used but this may harm some of the helpful critters that keep your garden ecosystem in balance.

• Downy Mildew

This can occur during damp or humid periods. It appears as dark lesions on the stems, leaves, and flowers. It can be confused with black spot. Over time, the underside of the leaves will show a covering of mildew.

Again, remove affected parts and treat with a spray of copper fungicide.

• Powdery Mildew

This is fairly common on many roses and the gray mildew coating is easy to spot. Nature often sorts the problem out without treatment being necessary. If it persists, use the same process above. Be sure to spray both sides of the leaves.

Conclusion

Caring for you Grandiflora Roses is not a major challenge and is worth the effort. Take the time to appreciate the roses regularly while looking out for any potential problems. If everything is set up correctly and you take quick action when necessary, you should be able to enjoy happy, healthy plants with masses of heavenly blooms.