Square Foot Gardening at Shades of Green

Welcome to Our Garden

Shades of Green has our own vegetable garden where we grow fresh fruits and vegetables year-round. The design is based on the principles of Square Foot Gardening as created by Mel Bartholomew. Square Foot Gardening is one of the easiest and most productive gardening systems ever invented, requiring a fraction of the time, space, and water of a traditional, in-ground row garden. If you want to learn the system, along with everything you need to know in order to be a successful vegetable gardener, start with All New Square Foot Gardening, 3rd Edition. It’s a great, easy-to-read book that will answer all of your questions. If, after reading it, you’re hungry for more, check out these other great resources from the Square Foot Gardening Foundation.

This garden is actually version 3.0. Our first efforts had several design flaws which were discussed in a previous post. Since relocating the gardens here (and getting 3 cats to keep the rabbits and rodents in check) we’ve had much better success.

Why Raised Beds?

Gardening in the heavy clay soil of North Texas is hard work, so why do it? It’s much easier to grow flowers and vegetables above our soil than in it. All you need is the right container. Flower pots will work, but if you want lots of plants you’ll need more space. One of the more popular solutions is a wooden raised bed. They look good, work great, and last for years if they’re built properly.

Our garden has 4 raised beds:

  1. The medium bed (far left if you’re facing the creek) is 4 feet wide by 10 feet long and 2 feet high.
  2. The short bed (far right if you’re facing the creek) is 4 feet wide by 8 feet long and 1 foot high.
  3. The potato box is 3 feet by 3 feet.
  4. The tall bed is 4 feet wide by 10 feet long and 37 inches high. The higher raised bed solves several issues faced by many would-be gardeners including:
    • Rabbits – Rabbits can’t climb, so they’re not going to eat the veggies before we do.
    • Dogs – Many people don’t even attempt to grow vegetables because they have large dogs that would trample the crops. Making a bed over 3 feet tall should solve this problem.
    • Small Children – Much like the dog issue above, small kids can “accidentally” play in the garden and do more harm than good.
    • Older Gardeners – A tall raised bed is a good option for older gardeners who can’t (or would rather not) bend over to tend a lower or ground-level garden.

Building Materials

When it comes to wood, you have many choices. There are tons of videos on YouTube showing how to build a raised bed out of everything from wooden pallets to cedar posts. Pallets are a mixed bag as you seldom know what type of wood they are made of or what that wood has been treated with. Cedar is a solid choice because it looks really good and is naturally resistant to rot and decay. The downside is that cedar can be expensive – especially if you’re building multiple beds.

For its combination of price and longevity, pressure treated lumber is the go-to option for many gardeners. It will last for 10-15 years or more, is readily available, and is affordable. (As of this writing, a 2 inch x 12 inch x 8 foot board sells for $12.77 at the nearest Lowe’s.)  If you’re concerned about the safety of pressure treated lumber, read this excellent article from Iowa State University. The bottom line is that today’s pressure treated wood is safe for use in growing food crops. If you’re still wary, use cedar or consider cinder blocks or galvanized steel.

If you want the bare minimum of construction, you can buy raised bed kits that are easy to assemble.

DO NOT use railroad ties! They are treated with creosote. As per the Iowa State article referenced above, creosote is a restricted use pesticide / preservative containing a mixture of 200-400 different compounds. It should never be used if it will contact food or drinking water!

Soil

A common question is, “Are the beds completely filled with soil?” Yes, they are. The beds are cross-braced to compensate for the outward pressure of the soil (especially when it’s wet). That much soil can be expensive no matter what you use. We have plenty of quality soil available and the equipment with which to move it, so it wasn’t a deal breaker for us. You could fill the lower half of a taller bed with fill dirt. Contact a local swimming pool builder. They often have dirt they’ve dug up for the new pools they’re installing.

Another option is to place cut up logs in the bottom. This idea is based on the centuries-old German practice of hugelkultur. As the logs rot, they’ll act as sponges to absorb and hold water. Your plants will appreciate this in the middle of a Texas summer. If  you want to know more, watch the video below.

What’s with the Grid?

Many people who garden in raised beds tend to under plant; meaning they don’t grow nearly as many plants as they could in the space available. Square Foot Gardening solves this problem by placing a permanent and prominent grid in the raised bed that breaks up the space into individual one foot squares. Following the Square Foot Gardening principles, you then plant each square with either 1, 4, 9, or 16 plants. This substantially increases the density of the planting, leaving no wasted space.

Our grids are made using 1/4″ twisted Polypropylene cord.  Polypropylene (PP and/or Plastics #5) is considered to be the safest of all plastics and is commonly used for food packaging. It’s a robust, heat resistant plastic, making it a good choice for constant exposure to sunlight and weather.

The cord is attached to the sides with stainless steel tablecloth clamps. They work great, install in seconds, and don’t rust or rot.

With two 4′ x 10′ beds, a 4’x8′ bed, and a 3′ x 3′ potato box, we have 121 square feet of garden. That’s 121 squares we can plant in. Using the square foot gardening system, you an get a LOT of produce out of that much space!

What’s the pipe for?

You’ll notice there is a 4″ PVC pipe sticking up out of each bed. That’s not for watering. It’s for compost and worms.

Compost is the single best thing you can put in your garden, but it making it is time consuming. Another great addition to any garden is worms. They help aerate the soil and their castings (poop) make great fertilizer. We’ve utilized worm towers in each bed to enjoy the best of both compost and worms. Food scraps are placed directly into the tubes and the resident worms do the rest. Shades of Green sells composting worms in the spring and we typically sell out quickly. Another great local source for composting worms is Texas Worm Ranch.

We built our worm towers exactly as described in the video below.

The short video below shows what happens inside the worm tower.

What about the grass?

If you simply place a raised bed on top of existing turfgrass, you’ll soon have a bed full of grass instead of vegetables. Most yards in our area have either Saint Augustine or Bermuda grass. Both spread readily and will quickly invade and take over a raised bed. We killed the grass under our beds with horticultural grade vinegar. We then scraped the dead grass down to the roots with a shovel. This also allowed us to level out the area where the raised beds were going to be. We then put down two layers of cardboard and put our soil on top. In time, the cardboard will rot and become compost. It will also help smother any bits of grass we missed.

To reiterate, you need to get rid of the grass before putting your raised bed in place. You have 2 options:

  1. Use a shovel or rent a sod cutter and remove the grass completely.
  2. Kill it, Cut it, Cover it:
    • Kill the grass with an herbicide (organic is preferable since you’ll be growing food).
    • Cut it. Once the grass has died, scrape it down to the roots with a shovel or use a weed-eater.
    • Cover it. Lay down cardboard or newspaper to smother any bits you may have missed that might re-sprout.

What do you plant and when?

Knowing what to plant when is important. Cool season crops like spinach and lettuce won’t survive the summer heat, and warm weather crops like tomatoes don’t like cold at all. Typically, planting times are calculated based on first and last frost dates. Those are the dates that, historically, an area experiences its first frost of the year (November 15 for Collin County) and the last frost of the year (March 15 for Collin County). Knowing these two dates will allow you to determine when to plant any crop that you might be interested in.

  • First Frost in Collin County, Texas – November 15
  • Last Frost in Collin Count, Texas – March 15

Understand that these dates are NOT set in stone. They are guidelines only based on historical data our USDA Climate Zone (8a). It’s possible that we could see a frost before Nov. 15 in a given year, and we’ve certainly had frost after March 15 in recent years.

If you’d like some more specific dates and/or time-frames, here’s some good resources that will help you determine what to plant when:

Okay, now what?

Like anything in life, there’s a learning curve when it comes to vegetable gardening. You will make mistakes. Things will go awry. Even if you do everything right, bugs and plant disease may come along and ruin your crops. But stick with it, learn from your mistakes and mishaps, and you’ll have more success with each passing season.

Raised beds do make a difference. They can make vegetable gardening so much easier than planting in our heavy clay soil. The information above should help you get off to a good start, as will this article on 7 Common Mistakes in Raised Bed Gardening. We recommend starting small with a single 6 foot by 3 foot bed or a 8 foot by 4 foot bed. As you learn more and get better at gardening, you can add more beds to grow more crops.

If you have questions about gardening in a raised bed, post them below and we’ll try to help.


Tim Wardell is a Texas Certified Nursery Professional and a Certified Square Foot Gardening Instructor who’s been gardening for most of his life.

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