21.5" Tapered Reservoir

21.5" Tapered Reservoir


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Product Description

Make any container a self watering planter box using our helpful reservoir inserts. These inserts irrigate your containers while you're away or busy, for weeks at a time depending on climate and plants chosen.

  • Made from durable, extra thick plastic (black with white fill tubes)
  • Waters 9" past edges in all directions (fits window boxes up to 39.5"L)
  • Can be linked to other reservoirs to reduce filling tube locations
  • Ideal for window boxes in hard to reach places or for busy professionals, people who travel, or small-space gardeners that just need a little helping hand.


Product Overview

Add a self watering reservoirs to window boxes, pots and planters, and ensure plants are always hydrated just the right amount. In container gardening a planter reservoir is an easy way to cut down on manual work while improving the health of roots. Each water reservoir insert featured below is its own self watering conversion kit that turns regular containers into nourishing plots for favorite arrangements.
A 21.5" planter reservoir irrigates window box planters up to 39.5" for approximately 2 weeks depending on climate and plants growing.
Even though it's just an insert, reservoirs are really self watering conversion kits for containers. Make any vessel a self watering planter with reservoir inserts designed to provide the perfect amount of water to root balls while leaving room for soil. A gravity fed capillary is at work between the water volume and soil volume, making each self watering reservoir a well of nutrients for plants to draw on as needed, irrigating for weeks at a time depending on climate and plants used. Shop our reservoir inserts and self watering conversion kits for thriving, beautiful container gardens.

Additional Information

Additional Info

We offer two tapered planter reservoir insert sizes that fit our standard flower boxes. Standard window box lengths of 24-72" are covered here, but reservoirs can be used on larger and smaller boxes. Call toll-free or click to chat with a representative for assistance finding the right size for you.

Please note: Tapered window boxes like our iron collection and our tapered liners are smaller at the base than the top. Double check all interior measurements for proper fit.


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(Qty-1) 33.5"


(Qty-1) 33.5"


(Qty-1) 33.5" or (Qty-2) 21.5"


(Qty-2) 21.5"


(Qty-2) 33.5"

Ships In 2-3 Business Days
Product Dimensions

21.5"L x 5.5"W top of taper, 4.5"W bottom of taper, 2 1/4" H

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