When your celery plant is established . Carefully dig a hole starting about 8inch away from you plant sloping towards roots ..Insert a 2inch or 3inch pipe into this about 8 to 10 inch into soil just away from roots,, Backfill soil around pipe ..water steadily down pipe till pipe overflows. Leave a minute, then fill pipe to top again with water ..You can use a weak liquid feed down pipe too .. Leave about 10inch to a foot of pipe sticking above ground level .. Hopefully This should help make sure your plant has got plenty of water where its needed and never dries out ... cheers.. Jim