Crop Rotation and Winter Soil Amendments


I have a plot 15 ft x 20ft at a local garden club where I have been growing mainly heirloom tomatoes (heavy feeders) in the same spot for 10 years. I use quality turkey and worm compost every year. But I hear more and more about crop rotation and the value of leaving the ground fallow for a year to allow it to rejuvinate itself. My plan for next Spring/Summer is to still grow tomatoes again but using large portable canvas grow bags instead of planting seedlings in the ground. Question is….is this a good idea for a relatively small garden? Should I go ahead with my plan to put compost on it now, cover it with straw mulch and leave it for a year before planting in it again. Or is it ok to just put compost on it now, cover in straw and plant in it again next Spring and forget the grow bags idea for next Spring/Summer?
Thank You


Wonderful to hear that you have been productively growing tomatoes for a decade and are thinking about how you can continue.

You are correct that tomatoes are heavy feeders – since they are flowering and fruiting plants they require sufficient and consistent nutrients to feed this growth.

Composted manures, such as worm or turkey manure, are top organic amendment choices for adding nutrients to the soil. Fertilizing the soil via composted manure is one way to continue to provide the nutrients that future tomato plants will need. Adding a commercial fertilizer that is high in phosphorus during the growing season is another way to provide nutrients.

You are wondering about leaving the soil unplanted (“fallow”) for a year so that the soil can rejuvenate itself. This practice generally involves leaving soil unplanted for one or several years. Fallowing soil can have multiple benefits such as increased moisture holding capacity and levels of nutrients in the soil; some nutrients like phosphorus (used by fruiting plants such as tomatoes) are able to rise closer to the surface during fallow periods. However, as an allotment gardener, leaving your entire garden plot fallow for one or more years will greatly limit the space you have to grow plants.

I would instead suggest crop rotation for your garden – the practice of not growing plants with similar nutrient and rooting needs in the same space every year. Crop rotation helps to prevent the buildup or spread of pests and diseases in a particular garden bed and optimizes the nutrients in the soil in any given year. There are different crop rotation practices, based on the number of plant families you are growing. Plant families include plants that are susceptible to the same kinds of pests and diseases – tomatoes belong to the nightshade family (Solanaceae) which also includes eggplants, peppers and potatoes. So if you plant tomatoes in the bed one year, you wouldn’t want to plant it or any other nightshades the following year if you are aiming to rotate your crops in order to not deplete your soil of nutrients or encourage diseases that affect this family (e.g., fusarium wilt). For nutrient optimization, a typical crop rotation order would be root crops one year, followed by legumes, leafy crops and then fruiting crops (tomato would be a fruiting crop).

If you opt to give your garden bed a rest, or grow something other than tomatoes, grow bags (like other containers) are a great way to add growing space to your garden that will ensure you can still grow tomatoes. Since grow bags are containers, you will likely need to adjust your normal routine of caring for your tomatoes. You should use potting soil in the bags, as it’s designed for growing in containers. Plants in containers need to be watered more frequently in order to keep them adequately hydrated (soil dries out more quickly when it has holes for water to escape) which leaches nutrients from the soil. Choose a fertilizer that’s higher in phosphorous for plants that produce flowers and fruits (phosphorus is the middle number in the NPK ratio; specialty fertilizers for tomatoes are available to purchase as well). When moving to container growing you may also want to consider choosing a variety of tomato that is resistant to blossom end rot (BER) since inconsistent water availability for plants in containers contributes to blossom end rot. Some of those that are resistant to BER though, are hybrids (e.g., Mountain Delight). If you want to stick with heirloom tomatoes I would go with cherry tomatoes since those are more resistant to BER.

Best of luck with your garden plot!

Oct 15, 2022