I filled a standing raised bed with a blend that doesn't retain water. - Ask Extension
On the advice of a local garden center I purchased Gardner and Bloome Raised Bed & Potting Mix. It says it is "Ideal for Filling Raised beds...
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I filled a standing raised bed with a blend that doesn't retain water. #871604
Asked June 04, 2024, 7:20 PM EDT
On the advice of a local garden center I purchased Gardner and Bloome Raised Bed & Potting Mix. It says it is "Ideal for Filling Raised beds". I spent hours making sure it was extremely well hydrated. I soaked it in tubs to make sure it was fully hydrated. Then I put it into the bed. The bed is on a stand so it is very important that it holds moisture rather than just draining out on the ground below. Also, I don't want to be flooding it with water everyday when out hot weather arrives. I had an extensive conversation about what I needed and they assured me this is the best product for this bed. But, even in this rainy weather it didn't even stay wet overnight. The next day when I was ready to start planting in it I realized the top had fully dried out. I don't want to plant in it without fixing the problem. I'm guessing it needs soil, is that right? What should I fix this with? I'm planning on planting asparagus and strawberries in this bed. Can I mix it with soil from my yard? Am I wrong and even though the top was completely dry (see photo), will this work? I would hate to plant it and have to redo the entire bed afterwards. Thank you so much for your expertise and information. Thank you.
Washington County Oregon
Expert Response
Raised beds do readily dry out, and setting up reliable drip irrigation is often recommended. If your beds dried out too quickly, it’s good to question the mix before planting. A challenge with helping gardeners online is that we can’t feel the texture and moisture to offer advice, so we need to rely on ingredient lists.
Does this product list the percentage of ingredients? I found university recommendations for 70% soil and 30% compost in a raised garden bed (example from Penn State). This mix you have lists no soil or sand as many planting mixes sold in bulk do. I will ask another expert to help answer you completely, because even considering the quotes from university sources I found (listed below), I’m not sure how to use or to modify the material you purchased. Maybe it will work well with proper irrigation?
So, here’s what I found in looking for advice to share. This article from OSU explains that raised beds can often have too much organic matter (mulch). This WSU Extension article says “Filling a framed bed takes significant quantities of soil. Purchase a garden mix from a local nursery or garden center. Mixes typically include clay, sand and an organic material such as compost, often in a 1-1-1 ration. These proportions allow water to move easily through the soil, and the organic matter holds nutrients well.”
This, Publication FS 270, from OSU, about raised bed gardening, says “When using a soil mix, good landscaping companies offer separate mixes for different uses, e.g., one with coarser soil may work well for a lawn but not for a raised vegetable bed. Choose a mix that has good nutrient and water-holding capacity.”
It is the weekend, so I expect it will be a few days before we can get another expert to help clarify what to do with your purchase.
Does this product list the percentage of ingredients? I found university recommendations for 70% soil and 30% compost in a raised garden bed (example from Penn State). This mix you have lists no soil or sand as many planting mixes sold in bulk do. I will ask another expert to help answer you completely, because even considering the quotes from university sources I found (listed below), I’m not sure how to use or to modify the material you purchased. Maybe it will work well with proper irrigation?
So, here’s what I found in looking for advice to share. This article from OSU explains that raised beds can often have too much organic matter (mulch). This WSU Extension article says “Filling a framed bed takes significant quantities of soil. Purchase a garden mix from a local nursery or garden center. Mixes typically include clay, sand and an organic material such as compost, often in a 1-1-1 ration. These proportions allow water to move easily through the soil, and the organic matter holds nutrients well.”
This, Publication FS 270, from OSU, about raised bed gardening, says “When using a soil mix, good landscaping companies offer separate mixes for different uses, e.g., one with coarser soil may work well for a lawn but not for a raised vegetable bed. Choose a mix that has good nutrient and water-holding capacity.”
It is the weekend, so I expect it will be a few days before we can get another expert to help clarify what to do with your purchase.
Your question has generated some discussion, and I have some information for you now.
The product you purchased is best as an amendment for garden soil rather than as the primary planting medium. Here is the fact sheet for it. Some of the ingredients are hydrophobic when dry, meaning they are very difficult to re-wet, and makes it a challenge to use in container gardening (which is what a fully raised garden bed is). This G&B mix is more suited to use in-ground than in a fully raised container garden.
We are concerned that you plan for a nitrogen source for your plants. These mixes (and many bagged and or bulk material from a landscape yards) have little or no nitrogen in them. The soil definitely needs to be amended consistently with sources of N (organic would be blood meal, chicken feather meal, fish emulsion, etc.).
So, with these bits of information, what do you put in your containers?
The publication Growing You Own, EM 9027, in the Container Gardening section, says in part, “A fairly lightweight potting soil is the best growing medium for container plants. Garden soil is too heavy for container growing. Most commercially sold potting mixes are too lightweight for garden plants because they don’t offer adequate support for plant roots.
If you buy a potting mix, add soil or compost to provide bulk and weight. Or mix your own with equal parts well-rotted compost; loamy garden soil; and clean, coarse builder’s sand. Add a slow-acting, balanced fertilizer (slow-release synthetic or organic fertilizers work best) according to container size. Add lime to bring the mixture’s pH to around 6.5.”
Reading the balance of the section on container gardening, I note advice about irrigating until water drains through the container drainage holes. It also references the need for a regular fertilizer (nitrogen) application and some minerals.
Asparagus has a big root system, so allow a deep and large area for it. It isn’t listed as one of the vegetables easily grown in containers. Strawberries in containers are discussed here, in EC 1307, look for the “Planting Systems” section. It gives recommendations on the best types of berries, soil, and more.
I hope the advice and cautions help you find success with your plants.
The product you purchased is best as an amendment for garden soil rather than as the primary planting medium. Here is the fact sheet for it. Some of the ingredients are hydrophobic when dry, meaning they are very difficult to re-wet, and makes it a challenge to use in container gardening (which is what a fully raised garden bed is). This G&B mix is more suited to use in-ground than in a fully raised container garden.
We are concerned that you plan for a nitrogen source for your plants. These mixes (and many bagged and or bulk material from a landscape yards) have little or no nitrogen in them. The soil definitely needs to be amended consistently with sources of N (organic would be blood meal, chicken feather meal, fish emulsion, etc.).
So, with these bits of information, what do you put in your containers?
The publication Growing You Own, EM 9027, in the Container Gardening section, says in part, “A fairly lightweight potting soil is the best growing medium for container plants. Garden soil is too heavy for container growing. Most commercially sold potting mixes are too lightweight for garden plants because they don’t offer adequate support for plant roots.
If you buy a potting mix, add soil or compost to provide bulk and weight. Or mix your own with equal parts well-rotted compost; loamy garden soil; and clean, coarse builder’s sand. Add a slow-acting, balanced fertilizer (slow-release synthetic or organic fertilizers work best) according to container size. Add lime to bring the mixture’s pH to around 6.5.”
Reading the balance of the section on container gardening, I note advice about irrigating until water drains through the container drainage holes. It also references the need for a regular fertilizer (nitrogen) application and some minerals.
Asparagus has a big root system, so allow a deep and large area for it. It isn’t listed as one of the vegetables easily grown in containers. Strawberries in containers are discussed here, in EC 1307, look for the “Planting Systems” section. It gives recommendations on the best types of berries, soil, and more.
I hope the advice and cautions help you find success with your plants.
