Gardening Again After a Flood

2025 has been a banner year for floods, and their destruction has been almost unfathomable. Here in the U.S., we were shocked and saddened by the Central Texas floods and their devastating death toll, but ruinous flooding has been happening all over the world. Large swaths of Africa have been severely affected, and Brazil has had its worst-ever floods. Pakistan, India, and China are no strangers to flooding, but even they have had bigger, stronger, and more frequent floods.  While dealing with such natural disasters is a nearly impossible task, dealing with flooding in your garden is very manageable. 

Where to begin: 

The only actions that can be taken while the water is still present are diversion or pumping it out, both of which can be impractical at best in an active flood situation. It is best to stay out of floodwaters; they can be full of creatures as well as organic (think sewage) and non-organic contaminants. Fire Ants, for instance, form rafts of many thousands of individuals to escape floodwaters, and you do not want to bump into one of those! Watch them in action here.

Once the water is gone: 

If there is trash, tree, or plant debris, you will want to get that out of your space. If you have flood-
deposited soil, you’ll have to decide if it should be removed. Although as little as one inch of silt can kill a lawn and only a few inches can kill a tree, removing the silt may not be the best idea. Adding and removing soil can be very hard work, is quite costly, puts you in danger of handling contaminants, and is damaging to the soil (more on that below). It might be best to simply scrape residue away from some of the bigger plants and start all over.

Assess your soil: 

Whatever you do, do not work wet soil – it can cause serious damage to the soil structure. Wet soil can easily become compressed, which can lead to compaction and drainage issues when it dries. Wait at least several days to weeks before digging, and if you plan to rototill, the recommended wait time is 90 days. You will want to determine how your soil biology held up to all the water. Soil microbes are an essential part of a healthy soil, and they need oxygen. If the soil is submerged overly long, water displaces the oxygen in it, and beneficial microorganisms can suffocate and die. Anaerobic microbes, which do not need oxygen, may take their place. A foul-smelling soil is an excellent indicator that this has happened and that the soil needs to be brought back to a healthy balance before any planting is done.

Plant viability:

 How your plants are affected by flooding depends on many factors: the length of time they were
underwater, what kind of plants they are, where they are in their lifecycle, the time of year it is, and the type of water that flooded. Warm-weather flooding will affect plants more than flooding that occurs when plants are dormant in chilly weather. Salt water will be much more damaging to most plants than will fresh water. Determining the condition of your plants can be tricky, as symptoms can take weeks and even years to appear. Vegetables and flowering annuals will show symptoms before trees and shrubs. Damage caused by flooding mirrors common disease problems, so the root cause is often unclear. If you have questions, contact your local Cooperative Extension to get expert information on your specific area. Here is a link to find the one nearest to you.

Vegetable gardens:

 First off, any produce that has gone through a flood should not be eaten. This is an EPA
recommendation, and it makes good sense. With all the unknowns in floodwater, it is the only way to be sure you are not ingesting contaminants. With fruiting vegetables, any fruit on them during the flood needs to be discarded, but whatever grows later should be fine. If you wish to err on the side of caution, wash those fruits thoroughly and plant a non-edible crop for a season.

What to do before replanting: 

As with all planting, start with your soil. A soil test is highly recommended after flooding. Water is notoriously good at leaching nutrients from soil, so even a minor water issue can affect what you’re planting in. If a soil test is not for you, you should still amend your soil and lightly fertilize (no heavy fertilizer while the plant struggles to come back). You can’t go wrong with the following: Apply BioAct SD to chew through organic material; use products like ROOT, EM-1, SCD BioAg or Mikrobs to return to a healthy microbial balance; add Earthworm Castings and, when the new plants are in, fertilize with Arber Soil and Root Food or any of our other excellent fertilizers; see our full range here.

Bear in mind that fungal diseases are common after floods, and they are best controlled by applying proactively; so, plan to treat as soon as you can. Cease would be a top-notch choice for this job, or choose another of our fine products on our Fungicides page.

Submitted by Pam