Have ready a large bowl of ice water.
Dice carrots, parnsips, turnip, rutabaga, and celery into cubes approximately ½″ square, keeping them separate.
In a large pot of salted water, boil carrots for about 5 minutes, then add parsnips, turnip, and rutabaga. Continue boiling for 5 minutes more, then drain vegetables and plunge immediately into ice water. Drain again and spread out