Question
Hi Will,

I have a jasmine plant that I bought about a  year and a half ago (replanted once at that time). It spent last summer outside on the north side of the house (with not that much light). It's been its second winter inside by the north side window (my house does not have much light). It's growing well but it does not flower (it did not flower during summer time either; I did fertilize it).

Now the biggest problem is that it has developed a dry white powder (mildew?) on the vines and the leaves. I water it approx. once every 7-10 days. I give it quite a bit of water but it looks dry before next watering (I was afraid of overwatering it but maybe I don't give it enough water).

Do you know what it might be and how I could treat it?

Thank you,
Oxana

Answer
Hi Oxana,

Let me deal with the non-flowering problem first.

Jasmine usually bloom in January. Normally jasmine is cut way back to half its size following a winter bloom and then new growth is kept pinched back to promote fullness until August. Keep the soil moist and fertilize regularly when it is putting out new growth. In August, discontinue the pinching In October; give it completely dark nights and cool temps (40 to 50 degrees) to promote January bloom. Keep the soil a bit more on the dry side and provide lots of sun during the day. It is usually recommended that you do this for 6 to 8 weeks. This will help set the buds. After that normal room temperatures and a sunny window will suffice. This is a difficult regimen to provide. If you can only do this for a few weeks, it is better than not at all. If you cannot do it at all, your plant will remain healthy but it may not bloom quite as much. In any case do not fertilize during the winter months. In the late winter or early spring, prune the entire plant back by half. New growth will soon emerge. Flowers appear only on new growth. Your north window may not provide enough light to produce flowers.

It is likely that your Jasmine has powdery mildew. The mildew spores may have been introduced if you used unsterilized potting soil when you repotted or when the Jasmine was outside. Try to keep the foliage dry and the humidity low if possible. Safer's makes a non-toxic sulphur spray for mildew, but any sulphur based fungicide spray will do. It is reasonably effective but will leave a strong sulphur odor on your hands, so use rubber gloves. Neem oil and horticultural oil sprays are also effective treatments for powdery mildew.

Please let me know if any of this is unclear or if you have any additional questions.

Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]

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