Answer: First off, are you sure the plants were all the same and from the same flat? Occasionally plants will be stressed in the retail process and consequently not take off like they should once planted. (A common stress is being rootbound, for example, or perhaps suffering shock from being removed abruptly from the greenhouse without conditioning.) Also, some varieties are more sensitive than others and some simply perform better in the garden. Next, there must be some difference in locations. Pansies do best in a rich, evenly moist yet well-drained soil well enriched with organic matter. They may sulk in areas with extremely acid soil. They are cold tolerant and yet prefer a protected location out of the wind. Newly transplanted pansies need to be watered until they are established, and of course any stress (undue heat or lack of water for example) prior to planting can have a negative effect on their performance later in the ground. I hope this helps your troubleshooting.
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