Thursday, October 22, 2009

Make Self Watering Planters. Easy Wicking Containers for the Greenhouse

Water. That's what plants in the greenhouse need. In northern climes, you need your crops growing all the time. Daylight hours are long but the growing season is short.  I top off the water supply to plants in my greenhouse by adding home made self watering systems to my  potted tomato and pepper plants. They get a constant source of water, so they can keep growing at will.

This is easier than you think! The wicking system saves water, keeps the plants growing and happy, and saves time. Plant roots grow throughout the entire planter, not just towards the bottom, so bigger plants can do well in smaller containers. 

The basic idea is that you have a separate reservoir of water where  'wicks'  draw water into the soil where the potted plant is growing.  

The blue pails in the picture above show an easy self-watering system . These old pails are about the same size,  and the light blue pail stacks perfectly into the dark one, with a 4 inch gap at the bottom and top between the 2 pails. In this case, the 'reservoir' of water is in the bottom pail.  I drilled 12 drainage holes in the bottom of the top pail (light blue) and dropped  4 cotton 'wicks' (from an inexpensive mop refill) down from 4 of these holes, to touch the bottom of the dark blue pail, when they are stacked. You can use other thick ropes for 'wicks',  just make sure they draw water up.

I drilled a bigger hole in the side of the bottom pail about an inch under the base of where the top pail would sit, leaving a 3 inch 'reservoir' for water in the bottom pail. This side hole is for overflow drainage of the water reservoir- so there is always a gap of air between the water reservoir and the bottom of the upper pail.  Knot the wicks at the inside base of the top pail and draw them an inch or two up into the dirt in the top pail, so the wicked water is dispersed in the soil. Fill the top pail with light soil (not potting soil but potting mix- this seems to be important for absorption) and plant your pepper, tomato or plants of choice.  Water from above directly on the soil, and/or below-  into the hole in the side of the bottom pail. Make sure there is always water in the reservoir and once in a while, flush it out by filling through the bottom drainage hole to overflow. 

The reservoir doesn't have to be under the planted pot - it can be beside it, or even inside it. Experiment! Self watering window boxes, self watering hanging baskets, this is an adaptable watering system. I use plastic containers rated as safe for food to plant in.

wicks are from a cotton mop


Denise said...

I have read about the wicking watering method but have not tried it. I will have to add it to my experiments this winter.

I understand the need for light with my short winter days approaching and being an unpredictable zone 5 climate. I am out preparing the greenhouse today for another cold season ;) Great article! Denise

Anonymous said...

Carol, I would like to plant a garden for the first time. And I would really like to try growing from seed. Could you recommend seeds? When should I start preparing my yard and buying seeds?

Greetings from said...


Choose a sunny spot, and start NOW (April) Be sure to add compost or peat to the ground. From seed, plant carrots, lettuces, green beans,peas, radishes, spinach. Get bedding plants for tomatoes.

Michelle Olchowski said...

Carol, I am in zone 3 in Saskatchewan so I am dealing with many of the same variables. I was wondering what vegetables do you grow in these containers and keep in your greenhouse. I have found the growing season is too short for peppers. What else do you think would benefit from growing in a greenhouse all summer?

Greetings from trekdigest said...

HI Michelle, Sorry for the late response, I just noticed your comment. Mostly I grow tomatoes, basil and hot peppers in my greenhouse, as the greenhouse extends the season, with higher temperatures at night.