Question
I currently have three cypress vine seedlings, and they are covered webs of spider mites. I am sure because I see tiny brown dots in the soil. I tried some insecticide last year but they killed the plants. Can you suggest a way to get rid of these pests?

Answer
Antony,
Since cypress vine is a tender annual it can be vulnerable to insecticides or other sprays, especially if they are used in hot, sunny weather.  Are you sure that you have spider mites? I'm not sure what the tiny brown dots are, but most spider mites are barely visible. Yes, you see some fine webbing, especially underneath the foliage, but the mites themselves are very, very tiny.

That said, insecticides don't kill mites because they aren't insects. They are arthropods and you need to use a miticide to kill them. These can be expensive.

Since you have seedlings, the first thing I'd do is to take them to the sink and run water over the young plants and wash them off. Sometimes this is a very effective way to deal with spider mites. Secondly, you might spray the plants with insecticidal soap. This would smother insects on the plants in case you don't have mites but have some other pest at work. If you get an insecticidal soap at a garden center it should be mild and not hurt the plants.

I don't know where you live but I can say that this vine, and other annual vines, are more prone to problems when grown indoors. The sooner you could get that plant outside and planted in the ground the better. If you've started it too early so that you still have some amount of time before it's safe to plant outside in your area you should think about starting some new seeds later. Start them three weeks before you plan to plant them outside so they aren't inside for very long.

I hope this helps,
C.L.