Articles

Why Does My Aloe Have Black Spots?

“We live in South Florida (Miami). My daughter-in-law has planted an aloe plant in the ground.  It’s growing nicely but has black spots on it.  Should she be concerned?” Question from Brenda of Miami, Florida

Answer: Florida rains are too much for succulent Aloe (Aloe vera). It is a dryland plant from the Arabian Peninsula that is best suited for cultivation in Southern California and the American Southwest in the US. It requires dry, fast-draining soil, once established. Too much moisture stresses aloes and invites fungal disease. Black spots on the leaves are due to fungal disease, but there are several things you can do to stop its spread.

To grow aloe well where you live, it should be potted. Before potting up your aloe, remove the worst of the infected leaves; just cut them off. Choose a pot big enough to accommodate its root system that has drainage holes at the bottom. Your aloe will need very fast-draining soil, such as Black Gold Cactus Mix. When you are ready to transplant, dig the aloe from the soil, remove the excess soil from its roots, and plant it in the pot with fresh mix. Finally, water it in lightly, and once its foliage is dry, spray it with a natural & organic, copper-based fungicide (click here for an example).

Place your potted aloe in a sunny to partially sunny spot under an eave or covered patio where it will not get rain. This will allow you to water it as needed. I recommend watering no more than twice a month, and water it from the base while being sure to keep its foliage dry.

From there, your aloe should thrive!

Happy gardening,

Jessie Keith

Black Gold Horticulturist

How Do I Prevent Rose Black Spot?

“Please give me advice on the prevention of black spot before it occurs.” Question from Carol of Drums, Pennsylvania

Answer: Black spot (Diplocarpon rosae) is such an annoying fungal disease of roses. Here are six measures to help prevent it:

1. Clean your bushes in fall and winter. Remove all fallen leaves and any dead branches from your rose bushes. The fungus overwinters on dead, infected plant material.

2. Apply a dormant oil spray before roses leaf out in spring. Dormant oil sprays deter fungal diseases existing on the plant. (Click here to learn more about horticultural oil sprays.)

3. Prune roses to promote aeration. Moisture on the leaves helps fungal diseases, like black spot, take hold. (That’s why roses grown in dry climates have fewer disease problems.) Prune off extra branches and sprouts to open up plants and help prevent black spot. (Click here to learn more about how to prune roses.)

4. Space roses to promote aeration. Space your roses according to nursery recommendations. Overcrowding can encourage foliar moisture and subsequent fungal problems.

5. Plant roses in full sun. When you plant roses in full sun, their foliage dries faster, which creates a less favorable environment for black spot to proliferate.

6. Water roses from the bottom. Bottom water your roses to help keep their leaves dry.

I hope that these tips help!

Happy rose growing,

Jessie Keith

Black Gold Horticulturist