SIP Construction:
Cost Estimations

SIP raised beds are a worthwhile investment. But they're more costly than other approaches. So it's important to know when to opt for an SIP, and when to just dig a hole in the ground. Despite the higher price tag, it's completely possible to get a return on your investment in the very first growing season. You just need a good strategy.

Let's start by looking at the basic price break down for an SIP. We'll discuss methods for keeping costs as low as possible. And then I'll demonstrate how you can leverage your investment for high yields and quick returns!

Maximizing Value with Your SIP Raised Bed:
• SIP Costs vs Conventional Raised Beds
• How to Reduce Costs of Building an SIP
• How to Get a Quick Pay Off From an SIP

SIP Costs vs Conventional Raised Beds

SIP raised beds require several key components, which make them more expensive than traditional garden beds. Both bed types can be constructed from standard lumber. However, SIPs also carry the added expense of a pond liner and corrugated drain pipes. Early in the planning process, gardeners may be quick to factor in those added costs. But then later on, when it's time to fill the planter, they may be shocked at how much potting mix they will need. If you're building several large sized SIPs, the potting soil could become a massive expense.

Although plants grow extremely well in it, potting mix is the most expensive component of large SIP raised beds.

Even if you're building a conventional raised bed, you'll still need to fill it with something. But you could simply get a bulk delivery of enriched top soil. Compared to SIP potting mix, that might cost less than half the price. In my calculations (shown above) my potting mix was purchased on sale, at only $3 per cubic foot. If you don't wait for a good sale price, you might end up paying quite a bit more! For optimal performance, it's a necessary expense. But you need to be aware of it right from the start.

How to Reduce Costs of Building an SIP:

Self-watering raised beds are excellent systems for growing your food. But in 2020 when COVID hit, gardeners saw skyrocketing prices on the most basic of materials. Everything from lumber to peat moss has been dramatically impacted by inflationary pressures. As a result, costs have become an ever growing concern when planning an SIP garden. For this reason, it makes perfect sense to consider strategies for keeping costs low, while still enjoying the benefits of wicking planters.

PLAN FIRST: If you want to keep costs low, then you need to take time to think things through. Determine the costs of ALL materials, not just the lumber. I've created this SIP potting mix calculator to help with your planning. If you avoid rushing into the project, then you can shop around and look for material, like potting mix, when it's on sale.

START SMALL: It might be tempting to go all in. An enthusiastic gardener sees the amazing growth in an SIP bed, and before you know it, plans are in the works to build a dozen massive SIP beds. If you have unlimited funds, that's fine. But if you've never grown anything in an SIP, it might be good to start with just a couple planters at first. This allows you to test the system, to see for yourself how these will work in your area. And the cost gets spread out over multiple seasons.

BED DEPTH: If you are on a tight budget, consider the bed size of your SIP project. Most critically, don't build a bed that's deeper than you really need. I always shoot for a depth of 16.5 inches. For a 4' x 8' raised bad, that requires about 32 cubic feet of potting mix to fill the upper portion. But if you opt for a 24 inch deep SIP, you'll need 52 cubic feet of upper mix! That's an extra 63% in costs with minimal benefit to your plants. You can still construct SIP beds that are higher up from the ground, if you prefer. But consider putting them on legs. OR perhaps you could create a cheap false bottom, inside of the sidewalls. Simple concrete blocks could do the trick.

WICKING CONTAINERS: If you're trying to have an SIP garden on the cheap, you might consider 5 gallon bucket SIPs or even 30 gallon totes. The tote SIPs are especially useful as starting systems. They support fairly large plants without requiring as much upfront investment. No need to buy a liner or any lumber. You still need to buy potting mix and drain pipes. But those materials can always be reused in the future if you decide to upgrade to a full blown SIP raised bed.

SIP totes are great starting planters. Later on, the old mix & pipes can be used to fill a wooden SIP bed.

How to Get a Quick Pay Off From an SIP

Even though wooden SIP raised beds come with a larger price tag, that doesn't mean they aren't a sensible investment. When gardeners look at the upfront cost, they might be shocked, expecting that it would take ten years for you to simply break even. Depending on what you grow in it, that might actually be true. But I've been able to demonstrate that you could see a return on your investment in the very first growing season!

LOCATION: The first step towards maximizing SIP productivity relates to bed placement. SIPs are so great, because they can supply an extended dose of water, allowing plants to grow and grow. But plants need more than just water. In particular, they need good sunlight. If a plant is not getting adequate light levels, then there's nothing that extra water or fertilizer can do to make up for that.

For that reason, your SIP beds should be strategically situated so that your plants can get as much sunlight as possible. This is most applicable to cooler, higher latitudes. In hotter climates, it's still good to choose a bright location, but you might need a shade cloth if the temps are too oppressive.

PLANT VARIETY: The key to a quick ROI, depends directly on what you grow. Large SIP beds are ideal solutions for growing large vegetables that tend to have extensive roots systems. Sure, spinach and lettuce love growing in SIP beds. But they don't require as much soil volume to maintain productivity. On the other hand, plants like peppers, zucchini, watermelons or tomatoes will make better use of a 16.5 inch deep planting bed. And they stand to yield more pounds of produce per square foot of bed space.

To save on material costs, annual herbs and greens could be grown in smaller SIPs:

MARKET VALUE: Pay attention to how much vegetables cost per pound. Some produce might be fairly cheap, costing only a dollar per pound. Meanwhile, sweet peppers or tomatoes can easily go for $3 or $4 per pound. If you want a quick return, then you need to grow vegetables that demand a higher price.

Consider my 4' x 8' SIP bed as an example. In one season I grew 133 pounds of tomatoes, and 41 pounds of zucchini. Just with those two crops, I was able to save $545 in a single season! Compare that to the construction cost in the chart shown earlier. Clearly, I would be able to recoup all of my investment right away. But If I had filled that entire bed with carrots or onions, it would not have been nearly as profitable.

GO VERTICAL: Large SIP raised beds are capable of sustaining massive vegetable plants. I mentioned that I harvested 133 pounds of tomatoes. All of those fruits were harvested from a mere two plants! I grew two indeterminate tomatoes in the corner of my bed. The plants towered at over 6 feet tall. By growing these plants vertically, I got a massive harvest in a super tight space. Essentially I was yielding nearly 29 pounds per square foot of planting surface. At a market value of $3 per pound, that translates into $86 per square foot. Can you grow $86 worth of lettuce per square foot?

Sweet peppers are also fairly profitable. In a different SIP bed I was growing 4 foot tall plants. The seven plants yielded 53 pounds of fruit over 9.3 square feet. In the end I got $22 worth of pepper per cubic foot. If you want to get the best return from your SIP, then I suggest using this approach to select the best candidates. As a point of reference, in the 4' x 8' example SIP shown earlier, you would need to yield about $15 per square foot in order break even in the first growing season.

PLANT SUCCESSION: You should view your SIP bed as prime real estate. It's positioned to get the best lighting. It gets the most profitable crops. To that end, be mindful if it is sitting vacant at any point during the growing season. In my climate, in zone 6, I was able to grow and entire crop of broccoli, during the cool spring growing season. They were harvested and removed before the temps had gotten warm enough for me to put in my zucchini crop. It's called succession planting. Depending on what you grow, you might be able to start with a spring crop, followed by a summer crop and even a fall crop. All within a single growing season!

Are you wondering how to fertilize such systems? Should you use compost? Read my multi-page article explaining the ins and outs of fertilizing SIP planters.

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