Answer: If you purchase container grown clematis, you can plant them in the spring or in the early fall, in early September once the heat of summer has passed. The selection may be better in the spring if you have specific varieties in mind.
Spacing will depend to some extent on which specific variety you plant, but as a rule of thumb maybe six feet apart. It depends on the mature size, some are larger than others.
Be sure to keep them watered correctly for best results. Your goal in watering is to keep the soil evenly moist like a wrung out sponge, not sopping wet and not dried out. To know if you need to water, dig into the soil with your finger. If it is still damp, do not water yet. When you do water, apply it to the soil surface and water thoroughly and slowly so it soaks down to the deeper roots. After watering, wait a few hours and then dig down to see how far the water soaked in; it can be surprising.
There is no set schedule for watering, it depends on your soil type and on the weather. Using an organic mulch several inches thick over the root area will help reduce watering needs as well as feed the soil gradually as it breaks down over time.
I hope this answers your question.
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