Water, Water Everywhere: Forming Your Greenhouse Watering Plan

Watering plants

Well, it’s almost that time again—growing season. That means suddenly finding your greenhouse stuffed to the ceiling with little seedlings or crammed full of nursery finds. It’s great to plan all those seeds or buy all those plants, but having a plan for watering a ton of thirsty plants is vital to anybody who gets the gardening bug in early spring and goes mad in the greenhouse.

What are your watering options?

You’ve got a number of options when it comes to meeting your greenhouse watering needs, but in my mind, there are only a few that are really useful in a small backyard greenhouse. Let’s run through the options:

Sprinklers – You weren’t thinking about installing sprinklers in your greenhouse, were you? Don’t. It’s a really bad idea. Not only are most sprinklers huge water hogs, they also increase the incidence of mold and mildew because of all the standing water they leave behind on leaves. Forget the sprinklers, they’re more trouble than they’re worth at the hobby greenhouse scale.

Drip irrigation – Ah, drip irrigation. I won’t lie, I’m pretty sure there’s not a better type of automated irrigation than drip irrigation. These little tubes distribute tiny amounts of water constantly to the roots of your plants, preventing them from drying out or developing puddles on their leaves that encourage disease pathogens. Drip irrigation is also super efficient when it comes to saving water.

Capillary mats – Another good option, capillary mats can be handy for seed starting or specific types of plants that need light soil. If your soil mix is too heavy, capillary watering is a lot more difficult and can cause roots to rot. You’ll need a capillary mat-friendly system to use these bad boys properly, which may require you buy a lot of special equipment or repot any plants you’re going to water using the system.

Hand watering – Small greenhouses with a hose close by can usually get away with hand watering with a water can. This is a cheap method of watering, and very personalized—you can choose which plants get watered, unlike with other systems. Depending on how many plants you have, though, the process can be pretty time consuming. Resist the urge to water from the top with a hose. Like with a sprinkler, this only encourages disease and wastes water.

The pros and cons of automation

Automation can be a wonderful thing, especially if you have a lot of very thirsty plants to water. If you’re not home during the hottest part of the day, automated watering may be the one thing standing between your plants and a miserable, shriveled death. You can set up systems to turn on at specific times or leave them running constantly, especially in the case of drip irrigation. Automation can free you from a lot of garden chores, but it’s not a perfect situation for the small greenhouse.

In a small greenhouse, every little plant counts. Every tiny shoot, every seedling is there for a reason—you planted it or started it from cuttings and you need it for something. That being said, if you don’t keep a close eye on those delicate wonders, bad things can happen, and much more quickly than they should. For that reason, more than anything, automated irrigation in a hobby greenhouse is sort of a mixed bag in my mind.

When I water by hand, I examine each plant for signs of disease or pests, check each one before I water to ensure they actually need watering and customize my fertilizing program based on what each plant really needs. I can do that because I have less than 100 plants in my greenhouse most of the time, but if you’re starting a bunch of seedlings that might be easier said than done.

A compromise between a single-controller drip irrigation system and simply hand watering would be to design a drip or capillary system (or mix the two) that places plants with similar watering needs together on a single controller. If your greenhouse is mixed like mine, you’d have all of your orchids on one drip system, your cactus on another and your African violets on yet another. You’d have a dedicated drip or capillary system just for seedlings, as well, since most seedlings have similar watering needs.

In my mind, drip lines and capillary systems are the only way to go in a small greenhouse if you must automate, but you have to make sure the plants you’re automating can handle what you’re throwing at them. There are plenty of plants like cacti and succulents that would prefer to dry out most or all of the way before being watered again and others like avocados that will drop dead if their roots are wet for too long. Consider the need of your plants before you dive right into the automated watering pool. I know all the cool kids are doing it, but the quality time that hand watering gives you with each of your plants may be the only thing that’s keeping them alive.

Kristi Waterworth
image: batintherain via Compfight cc
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