Friday, April 26, 2013

DIY Square Foot Garden (SFG): Making a Hoop House

Hoop House with Cover Closed
Easy, Functional Hoop House

Instructions by Bruce

My last two posts were about making a square foot garden: building the raised beds, and mixing the soil and planting. Today is the final chapter, on what it takes to sustain the garden: water, fertilizing, and temperature control. Making an inexpensive hoop house will allow you to plant earlier and get growing despite nighttime temperature dips. You can also use the hoop house to foil most bugs while providing the diffused lighting that seedlings prefer. I’ve also included a few tips on early-season garden maintenance. So without further ado, let’s get to it.

Hoop House with Cover Open
Plastic Option Might Need Ventilation During Day
PVC pipe can be fashioned into cheap and serviceable hoop house. Be sure to get Schedule 40 (thin wall), not Schedule 80 or 125, which it too hard to bend. To cover the hoop house, there are two main choices: non-permeable plastic or a permeable covering like white shade cloth or row covering. Non-permeable is best where it rains and/or temperatures drop below 40 degrees or so at night. Use a UV-resistant plastic at least 3 – 4 mils thick. Plastic will trap more heat, so needs to be monitored and opened up in direct sunlight on hot days. It’s not flexible so it can rip if stretched too tightly. Permeable covering works well if there’s no rain and temperatures are more moderate. It can be left on during most days, with the added benefit of blocking hungry insects and birds and providing diffused light. In Santa Cruz and surrounds, we start the season with plastic and switch to row cloth when it stops raining for the year and nighttime temperatures get moderate.

Let us know with a comment if you have more advice for a DIY SFG!

Square Foot Garden with Seedlings
Success! Bean and Squash Seedlings
Hoop House for 4' x 4' or 5' x 3' Raised Bed

1 – 20' piece ½" schedule 40 PVC tubing
Ratcheting PVC pipecutter or hacksaw
Yardstick or tape measure
Pencil or scribe
6 – ¾" pipe loops (strapping)
12 – ¾"  #6 wood screws
Screwdriver bit for drill
~10' square sheet of 4 mil UV resistant plastic or white row cloth
Box (12) of large (2") binder clips or other clipping devices

Cut bell-shaped end off PVC pipe with pipecutter or hacksaw. Cut into 3 equal pieces, approximately 6.5' long.

Measure and mark the center of the longer sides of the raised bed. Attach pipe loops (strapping) to inside of bed, approximately 1" from top of board, driving wood screws with cordless drill. Add one loop on each end and one in the middle on each board.

Put one end of PVC pipe into pipe loop and bend to fit into pipe loop on opposite board. Repeat with other 2 PVC pipe sections. This is your hoop house frame.

Unfold plastic or row cloth and lift to cover bed over hoops. Clip in place with binder clips, a minimum of 3 clips on each end hoop. If your bed is in a windy area, you can also clip to the gopher wire on the bottom of the bed, or pull in the corners at the bottom and clip. Don’t pull the plastic tight, it needs to flex in the wind, otherwise it will rip.

Transmitting part of thermometer
Thermometer Transmits Temp to Receiver
Garden Maintenance Tips

Water check: test garden every day when plants are small (and before germination) to determine whether water is needed. Use a hygrometer, or just stick your finger 2” into the soil and see if it feels damp. If not, add water.

How to water: classic SFG procedure is to fill up a watering can and leave it in the sun to warm, and use that water in mid afternoon. In practice, you might need to check and water early in the morning before work. Don’t water in late afternoon or at night.

Max and Min temperature notes
Logging Max and Min Temps to See Trend
Temperature check: You might want to get a maximum/minimum wireless remote sensing thermometer for the garden to monitor how cold it gets at night. We bought ours at LL Bean several years ago, < $20. This is useful to determine why plants don’t germinate, which could be caused by low temperatures, inadequate water, animals in the bed, or bad seeds. It’s also useful for monitoring high temperatures if plastic is used in the hoop house, to know if it’s best to remove the plastic during daytime.

Fertilizer: Not needed during first month or so, but be prepared to add compost to bed as plants grow and level of soil falls. 

Germinated Squash Plants
Our First Goal is Realized!


  1. I did similar to you on the PVC hoops, but i put the hoop attachment on the outside of the bed. I didn't want to leach any foreign materials into the soil. Since the pipe straps that I purchased were steel and the screws were zinc and other metals, I didn't want to take a chance. I purchased one 10 foot PVC pipe per hoop.

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