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The Plant Lady: Soil prep is dirty work that pays off down the road

Here’s how to start your vegetable seeds indoors

"The Plant Lady" Marlene Simon, a horticulturalist at UC Davis, shows how to start vegetable seeds indoors, Friday, February 8, 2019 in Davis.
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"The Plant Lady" Marlene Simon, a horticulturalist at UC Davis, shows how to start vegetable seeds indoors, Friday, February 8, 2019 in Davis.

Did your summer vegetable garden not produce to your expectations? Most likely, your soil played a critical role in this. Often overlooked, soil is key to a healthy, productive garden. The good news — February and March is the time to prep your garden beds (raised or in ground) for a productive vegetable harvest.

If your garden did not perform well, the first thing you want to do is remove as much plant material from last year’s garden as possible. This should be done directly after the season, however, if you missed that window, remove any debris now. Even small portions of roots and leaves can harbor certain plant diseases. Many gardeners prefer to till plant debris under — this is okay, but if disease is suspected or pests were abundant, I recommend debris removal instead.

Second, do not work wet soils. With a wet late winter/early spring, it can be tough to get into the garden. Regardless, it is crucial you wait until soils are a crumbly consistency before you dig or turn it. Working wet soils will break down the air pockets and can reconfigure them. If you want to hasten the time until which you can work the soil, try laying plastic or plywood over your beds to keep them dry.

Third — it is time to amend your soil for nutrients and/or structure. People are often surprised when I tell them that at most I fertilize two times after my plants go in the ground. Many years I altogether skip post-planting fertilization. The key is to start with a healthy soil, which in turn supplies everything required for the upcoming season.

Following is a breakdown of common soil amendments and their characteristics.

Red lava fines (dust)

Heavy clay soils can be difficult to garden in. They are ideal for holding water, but this can be a detriment as well. Heavy soils can inhibit deep root growth which prevents plants from growing to their full potential. Adding red lava fines (dust) breaks up the clay, creating a quick draining, highly aerated soil.

Gypsum is another known soil softener, however the results are short-lived ( six to 12 months). Red lava is an inorganic material that will not break down, therefore you will not see a decrease in soil volume and height over time. As such, red lava fines are ideal for permanent ornamental beds. How much to add depends on many variables, but I recommend at least 6 inches of lava dust to be turned under.


Compost is broken down into green and brown organic material (nitrogen/carbon). Microorganisms, fungi, bacteria and earthworms break the components down, releasing nitrogen, phosphorous, potassium and micronutrients. Homemade compost will work, but if that’s limited in supply, you can purchase. A word of caution: Not all composts are made the same. Many bagged composts are redwood debris, with little nutrient value.

In addition to benefiting from the added nutrients of compost, your soil structure will also be reconfigured over time. Clay soils over many years will become more loam in nature, which leads to better drainage and aeration. The downside is that since compost is an organic material, it will break down. If used to raise your soil level, be prepared to see a decrease in soil volume at the end of the season.

Compost is also my go-to top dressing. When laid on top of your soil, it will insulate both soil and roots from heat and water loss. Additionally, earthworms will move up closer to ground level and help add nutrients.


Manures such as steer, chicken, sheep, bat or horse add various nutrients to your garden (nitrogen being the primary). Sheep and chicken have the highest levels of nitrogen, with chicken also being a good source of phosphate. Nitrogen is the greening nutrient, so adding manures will help your plants grow lush and green.

If harvesting from a farm or stable, make sure the manure is broken down. So-called “hot” manure will burn your plants. Be careful with horse manure, as you may end up with oats growing in your garden.

Soil Conditioner, Soil Booster, Garden Soil

These are ‘one stop’ bagged amendments. The base is generally a redwood byproduct with various manures or fertilizers added, such as bat guano, sea kelp and chicken manure. Be careful with these; .they can pack a punch of nutrients, so they should be mixed into the soil well.

I have to give a special mention to alfalfa meal. There are many other nutrients that can be mixed into soil before you plant, but my favorite is alfalfa meal. It is a mild source of nitrogen and other macro and micronutrients. Alfalfa pellets/meal can be found in the fertilizer aisle of nurseries but I buy mine in large bags at animal feed stores. If you buy at a feed store, make sure molasses has not been added. To use, the pellets can be broken down in water or laid on top of the soil and turned under.

There is no correct recipe for perfect soil amendment. Many longtime gardeners have their go-to blend which they swear by. In spending time on the soil before planting, you are not only creating a healthy base for the future, but you are also making fertilization for the upcoming season a highly unlikely need.

James Patrick has covered the beer scene from Maine to California. (OK, mostly just those two.) He’s worked at newspapers in six states as a sports reporter, sports editor, social media editor and newspaper carrier. He’s as comfortable drinking a High Life as a wild-fermented raspberry sour.