You know the process known as laying in fresh soil, which unless you dug it up in one corner of the backyard and moved it across the lawn, is a newcomer to a foreign land. Don’t be overly excited about this wonderfully fluffy new dirt you just bought, because it’s not quite ready to work as hard as you’re imagining. While it may be an improvement over what you have, it has entered the realm of dirt interrupted.
Take note raised bed gardeners.
Soil that is excavated from one location, and deposited in another is going to slow you down. Yes, building raised beds is way easier and faster than improving the quality of your existing ground soil, but the native and the immigrant aren’t on the same page here. They don’t speak the same language or share the same needs, and in the average raised bed planter – your plant’s roots will be in both soils. Not good! This will throw a wrench into both your watering practices and nutrient delivery.
Ever paid much attention to the stark difference in color between newly installed sod and established grass in a lawn? It’s because of the vast difference between the soil the grass seed was grown on, and the soil the surrounding old lawn space occupies. This is also what makes sod lawns so much harder to keep healthy, and watered. Eventually that sod will acclimate itself to this new environment, but rooting into two distinctly different soils will make it a needful thing prone to insect and disease attack.
The physical properties of your ground soil and the newly installed imported soil are most likely as different as night and day… in the beginning, anyway.
For starters, there are water movement channels in established soil that are totally destroyed when you dig up soil and move it from place to place. Deep tilling and turning also messes up the natural draining system native ground soil has. So you see, this part happens even you dig the soil in your own backyard, you’ve created chaos, and getting back to normal takes time. Which reminds me… you can have several types of soil on a single property. Remember – soils are built up deposits of decayed organic matter. It never falls evenly like peanut butter spread on toast!
Make it deep.
The most common backyard raised bed garden is only 4″ to 8″ deep. How deep do your plants root? Things like tomatoes, and cucumbers put down some long roots, this shallow frosting you’ve installed is not enough to support either their water distribution needs, or good movement of fertility either. How deep should it be for good instant results? Try 12-15 inches… just about knee-high. Yup. This means a lot more soil must be purchased, but this isn’t frosting, it’s a life support system. AND weeds won’t grow up through this much dirt! No need for plastic (tsk tsk) or newspaper in the bottom to block this activity.
Trying to keep the cost down? Mounding soil above the retaining wall is only wasting your funds. It will all wash off or blow away. This garden on the left? They will lose most of what is above the boards.
It’s also a good idea to mix the new soil with the existing soil down into the top 4″ of your ground level before completely filling the raised planter. This will help to create a little smoother transition from one soil to the other; especially if you’re covering super sandy or hard clay soil.
Speaking of clay, it does not drain well. So, if the reason you’ve decided to leap into raised bed gardening is you need a jack hammer to dig a wee hole for seedlings, why not just put some dirt in a huge tub without any drainage holes! The new soil will drain very nicely, it’s loose and fluffy, and everything that enters on the surface will pool where your new layer meets hard pan clay ground. For you, this no-work raised bed garden also requires a blind drain, or French drain as some call it. Just as you put gravel in the bottom of a huge flower pot to give water a place to go so it won’t suffocate plant roots, you have engineer drainage in this clay-ground-gardening miracle solution. If you don’t, instead of growing with sweet abandon, when your plants really start sinking down deep roots, they will go into decline, perhaps become diseased if they don’t just rot away from the bottom up.
Sound like way too much bother? Then use fabric pots, and buy the good ones from Smart Pot or Geo Pot. Cheap stuff never holds up long. That’s why it’s cheap. And make sure you’re getting GOOD soil. This raised bed garden below has nice looking soil in the only two planters that have much growth going on. Getting too frugal doesn’t mean you’ll be successful at growing food. It takes more than some seeds!
When putting in a new growing bed like this, it’s a wise idea to plant a cover crop the first season, whose roots will work to establish the physical properties your garden plants need to deliver a great harvest in the most trouble-free manner possible. Yeah, I know, you’re not a farmer but they do this for important reasons besides restoring the nitrogen level after a heavy-feeding crop like corn. Till that spent acclimation crop in late fall or super early spring. Work up your soil well. Let it sit and settle for a bit. Then worry about planting your homegrown veggie garden.
Seriously, all that work?
You could work in some great compost, but it won’t be quite the same as last year’s roots are part of the structure building process imported soil needs. By the way, this acclimation period isn’t noticeable for growing things like bushes and perennials, which take years to grow to their expected stature and and display assets. This is totally different when you’re growing food. It’s a fast crop. You need results in weeks, not years.
Like any foreigner arriving from far away, immigrated soil needs to rest up from the trip, get familiar with the territory, and learn how to speak the language in this new place. It doesn’t happen overnight. So much for lasagna gardens. They’re even worse when it comes to providing roots an environment that will grow you a bumper harvest.