Soil Preparation Before Planting in a Raised Bed That Has Been Used Before

Question from Stephanie:
We have just moved to a house in Los Angeles, equipped with two 7-foot-long boxes already filled with soil that’s been in there for a year or more. My daughter and I would like to plant an herb and vegetable garden but have no idea how to start. I’m assuming we have to prep the soil before we do anything else. How might we do that? Thank you very much!

Answer from Pat:
When planting vegetables in raised beds or the ground it is always necessary to prepare the soil first. You are exactly right to surmise this must be so and I am glad you asked me to explain. I presume your boxes are filled with top soil or something akin to garden soil. If so, this is good. Potting soil is meant for filling pots, not for filling raised beds. I also hope they are in full sun—vegetables need full sun. We will also hope that whoever installed them also covered the bottom of each one with hardware cloth or chicken wire to keep out gophers. We will just trust they did that. If not, you can address that concern at a future date.

The first thing to do is to remove and dump all weeds. You may also wish to purchase a drum composter (the kind with 2 compartments) or find a place for composting and build the 3-bin type, but you can do all this later. Next, go to a nursery or home-supply store to purchase supplies. Before leaving for the store, measure the square foot area of your beds so you will be able to purchase adequate fertilizer for your needs. You can also make a list of transplants of winter vegetables and herbs (cool-season crops) and purchase plants and seeds of these.

In order to prepare the ground for planting your two raised beds, you will need to purchase a large (2 or 3 cubic-foot, not the small size) bag of composted organic soil amendment, sometimes called “Planting Mix” or “Compost” or “Organic Garden Mix”. Read the directions while you are at the nursery garden or home supply store where you make the purchase and make sure the product you buy is designed for mixing into soil or into a planting hole at the time of planting. Do not purchase “Potting Soil” or any product called “Mulch” or “Topping”. These products are not soil amendments. They are not fully composted or “nitrolized”, and thus if they are combined with soil, they will rob nitrogen from the soil in order to rot.

Also purchase a box of organic fertilizer designed for fertilizing vegetables. (This is the easiest way to go.) Read package directions and make sure you purchase enough for the square foot-area of your boxes. If you prefer you could use chicken manure and use that instead of fertilizer or you could purchase a bag of Seabird Guano if it is available at the store where you go. It is a very effective fertilizer for all vegetable crops.

For tools you will need: 1 spade, 1 garden rake (not a grass rake), 1 hoe (optional), 1 single or triple-hook cultivator, garden gloves, and one or two trowels.

When you arrive home, begin by digging up and turning over the garden soil with your garden spade. If you see worms, that’s just fine, leave them in the soil where they belong. However, if you see white grubs curled up sideways, pick them up and remove them. You can throw them into a clean bucket as you work and then put them into an empty tuna can and set it near some trees and shrubs for the birds to get later or simply bag them and throw them in the trash.

Then pour half the bag of soil amendment into one of your beds and half into the other and use the garden spade or a hoe to mix it into the top 8-inches or so of the soil. (Cultivators don’t work well for this job. They leave too much soil amendment on the surface of the ground. That’s not what you want. Organic soil amendment needs to be thoroughly combined with soil, like flour in cake. Its purpose is to lighten heavy soil, improve the water retention in light soil, and create an organic environment for the growth of healthy bacteria in the ground that aid plant growth.

After c mixing in the soil amendment, use the garden rake to rake the soil flat again. Then sprinkle on the fertilizer applying the amount recommended on the package for the number of square feet of space you have. Use the cultivator to work the fertilizer evenly into the top 6 inches of soil. A cultivator works well for this since it doesn’t carry the fertilizer away from the spot where you put it, whereas a hoe would do that. After doing all these jobs water the bed thoroughly with the hose, applying an inch or two of water or however much is necessary to dampen the ground thoroughly to a distance of about 8 or 12 inches. Then let your beds settle over night. The next day plant your crops.

I am planning on covering soil preparation this week on television next Wednesday, August 1. The show is San Diego Living, and I will be appearing live between 9:00 a.m. and 10:00 a.m. for 15 minutes of the 1-hour show on San Diego Channel 6. The segment will be shown later on U-Tube. Just Google “Channel 6-San Diego Living” and you will be able to get it. We will also run it on this blog. On September 11, I am planning to go up to Hollywood to make a few videos on fall planting and we’ll put them onto my blog as soon as possible thereafter.

Please also follow the instructions in my organic book. How to prepare soil and how to plant vegetables are covered in detail on pages 39 to 42 and also in many other places throughout the book, especially in the sections on vegetables in each monthly chapter. If you don’t have a copy of this book I recommend you get one and begin reading the parts that pertain to vegetables each month, beginning in September. It will be a huge help since it takes gardeners by the hand each month and tells them what to do and when to do it. There are many tricks and hints with winter vegetables that most people don’t know. Knowing the facts will help you have success. Now good luck and have fun!