Gardeners and farmers don’t control the weather. Especially in spring, unpredictable heavy rains sometimes mean water can’t drain away fast enough, leaving soil impossible to work. How do we adapt when it’s too wet? What are our best options for planning ahead?
As part of your rainfall preparedness, think about the average weather in your locality. Figure out which crops are already marginal in your climate, and decide whether they’re important enough to warrant extra protection.
For crops you do decide to keep, try the following tips to prevent flooded plants and soil erosion. First, where feasible, plan to use raised beds or ridge planting to help excess water drain sooner. Minimize tillage, because tilling accelerates nutrient burn-up and the loss of organic matter. Also avoid tilling right before a forecast of heavy rain. Instead, use a broadfork, which will open up the soil and allow it to dry faster. You might be able to mow, which will prevent weeds from seeding and prevent any cover crop or previous food crop from getting bigger. Or, lay tarps over the cover crops and weeds and wait for them to die. You might also use a string trimmer, a scythe, or a flame weeder to bring down unwanted vegetation. We successfully used our wand-style flamer to kill weeds in the potato patch one spring when it was too wet to hill the potatoes.
Increase the organic matter content in the soil so it can absorb more water in a manageable way, without compacting and becoming anaerobic. Incorporate compost, cover crops, organic mulches, crop debris, and weeds, all of which improve soil structure, organic matter, and humus. The effect of compost lasts longest. If you’re practicing no-till methods, lay these materials on the soil surface and expect the incorporation and benefits to be slower to arrive.
Maximize the volume of living roots in the soil from food and cover crops, and use both deep-rooted and shallow-rooted crops; root channels improve soil structure and drainage. Keep these roots in the soil all the time, or as much of the time as possible, whether they’re alive or dead, to tie the soil together and prevent erosion. Consider no-till cover crops, which will become mulch. Their roots will support microbial growth, form active organic matter, and rapidly release nitrogen to the plants. Low-growing, noninvasive cover crops can be planted in pathways.
Avoid a fallow period at times of the year when your plot could receive a lot of rain. For your location, that might mean year-round.
You can also try some unconventional growing tips for crops you think are in danger. For example, the International Cooperators’ Guide “Grafting Tomatoes for Production in the Hot-Wet Season” recommends using eggplant rootstocks for tomatoes when flooding is expected, as eggplant roots can survive for multiple days underwater.
Cover Crucial Plantings
Cover soil in key locations to assist with drainage. Before a storm moves in, cover the soil where you plan to plant. This can be accomplished with temporary caterpillar tunnels, low tunnels, plastic mulches, and tarping (or “occultation”). Unfortunately, these can keep some areas of the soil dry while causing runoff that makes other areas wetter. But this strategy can help you finish crucial plantings in a timely way, leaving the problem of oversaturated areas for you to resolve later.
Hoop houses and caterpillar tunnels can help protect crops from deluges. Large structures do cause runoff, but you can plan ahead by constructing a drainage system. When we built our hoop house, we made a ditch around three sides of it to channel runoff downhill. Some people who have roll-up or drop-down sidewalls install plastic guttering on the “hipwall” lumber that these structures need, and collect the rainwater for irrigation.
Despite your best-laid plans, you may still need to take immediate action for serious problems. If water drainage is a big issue where you grow, you may need to consider a swale. A swale that’s 18 inches wide by 8 inches deep in average-draining soil can infiltrate approximately 1.6 inches of rain per hour per 20 square feet of contributing area. Similarly, a “grassed waterway” — a large, gradual, grass-covered swale that you can graze or mow — conveys surface water to a stable outlet without causing erosion.
Another option is a dry well, or “French drain,” which is essentially a hole full of rock. This will likely need to be a large hole, and might require a lot of rock (that is, expense) and maintenance to keep it free of sediment and leaves. Other somewhat expensive options, perhaps best for large plots of land, include establishing tile drainage, which involves plumbing your field to remove excess water below the surface of the soil, or keyline plowing, which follows the contours of the land to open compacted soil and distribute water toward naturally drier areas.
First Aid for Field Planting
If you can’t plant when you want, try transplanting instead of direct seeding. We did this once with our winter squash when our plot was hopelessly wet. We were able to transplant the squash fairly young, and didn’t have a significant delay for our harvest.
You can also consider a different, faster-growing plant cultivar that you can sow later and still harvest in time. Some leaf lettuces, including ‘Salad Bowl,’ ‘Bronze Arrowhead,’ and ‘Tom Thumb,’ need only 46 days to mature, while romaine lettuces can take 70 days or more. Baby lettuce mixes can be ready in as little as 21 days from mid-spring to mid-fall.
Another option is to choose a different, faster-growing crop that you can sow or transplant later. Brassicas, such as kale, arugula, and radishes, are ready in 30 to 35 days. Many Asian greens will be ready in about 40 days. Try ‘Maruba Santoh,’ ‘Tokyo Bekana,’ ‘Yukina Savoy,’ Chinese cabbages, komatsuna, ‘Senposai’ (a cross between komatsuna and cabbage), mizuna, bok choy, and tatsoi. Some salad crops, such as lettuce, endive, chicory, spinach, Swiss chard, and pea shoots, can be harvested after a relatively short time. One summer, we sowed ‘Tokyo Bekana’ cabbage as a lettuce substitute, and it took only 20 days to grow to baby size, and 45 days to full size.
Corn salad, land cress, sorrel, parsley, and chervil are ready in 35 to 45 days. Beets; collards; kohlrabi; turnips; and small cabbages, including ‘Farao’ and ‘Early Jersey Wakefield,’ are ready in 60 days.
Of course, when choosing plants, keep your crop rotation in mind, as well as the next crop you intend to plant in that spot. With this attention to detail, plus your perfectly prepped growing plots, you can pull your crops through heavy spring rains for seasons to come.