Many gardeners use a cold frame or a small area of the garden to start plants from seed. The soil surface is kept damp until the seed sprouts. When the plants start growing their second set of leaves, they are transplanted, thinned and spaced into rows or beds where the plants can depend on drip irrigation for the rest of the growing season.

Examples of plants started this way include carrots, broccoli and cauliflower, onions or any other plant with seed that needs to be planted just under the soil surface and requires consistent moisture to sprout.

Drip irrigation is more efficient than sprayers when irrigating deep to the roots but sprayers are better at keeping the soil surface damp in a seed bed. Micro-sprayers deliver a very fine spray over a small area, just enough to keep the soil damp but not enough water to cause a problem with runoff or compaction.

The seed bed sprayer is temporarily laid over top of the drip irrigation dripline in this 4' x 9' raised bed

Hose end detail of the seed bed sprayer

The surface of the seed bed should never be allowed to dry deeply otherwise the seed may stop growing completely. Generally it only takes 20 minutes or so to wet the surface of a seed bed, then we move the seed bed sprayer to another seed bed. Repeat daily or more often depending on the weather.

Seed bed sprayers are only needed for a period of days and are then removed when the seed sprouts. We want to build a system that is lightweight and easy to move out of the way.

Seed bed sprayers should be completely independent of the garden drip irrigation system. That way, we can leave the drip system intact and undisturbed while we move the seed bed sprayer from bed to bed in a day.

A garden hose is ideal as the water source for our seed bed sprayer. It's flexible and easy to move. You can leave the water running while you move the seed bed sprayer from bed to bed if you don't mind getting a bit wet or you can install a valve at the end of the garden hose to shut off the water while you move the system. Better yet, simply turn the sprayer heads off when moving the system.

The parts needed for the seed bed sprayer include a FLR3 filter, PR2 pressure regulator and FC16 adaptor to attach to a 8' length of 1/2" T250 tubing. Use an OE7 End Stop to close the end of the 1/2" tubing. Use a punch to install one FB10 connector, a 24" length of T350 1/4" tubing and one sprayer about 1' from the closed end of the tubing. Install a second FB10 connector, 24" length of 1/4" tubing and sprayer 5' from the closed end of the tubing.

You could make the seed bed sprayer system a lot longer but it the added length will make it difficult to move. Better to keep it short and move the system often.

Use two SP8 half-circle sprayer heads on SP5 sprayer stakes for 4' x 8' or 5' x 12' raised beds or cold frames. For a wide row in the garden, you may want to try SP6 bow-tie sprayer heads for a long, narrow spray pattern. The spray patterns should overlap for full and even coverage. Modify the design to fit your garden.

When all the seed has sprouted, hang the seed bed sprayer out of the way until next season.

Close view of the half-circle sprayer

 

Here's the parts list:

• 8' length of T2100 tubing
• 1 x FLR3 Filter
• 1 x PR2 Pressure Regulator
• 1 x FC16 Adaptor
• 2 x FB10 1/4" Barbed Connector
• 2 x SP5 Sprayer Stakes
• 2 x SP8 Half-circle Sprayer Heads
• 2 x 24" lengths of T3100 1/4" tubing
• 1 x OE7 End Stop
• 1 x TL2 Punch