All gardens need water, but what do you do when we get too much? It’s a question quite common in the nursery at the moment. Floods and long-standing water can be devastating to a garden and in the very least it’s something I think most are familiar with. With recent rain and flooding affecting more than just the garden for some.
How much damage is done will depend on the types of plants, the type of soil they are growing in and whether there have been any contaminants in the flood water.
When plants are subjected to water-logged soils for long periods of time, roots are deprived of essential oxygen. Water fills all of the pore spaces in the soil and roots can begin to suffocate and die.
Native trees are fairly well adapted to temporary deluges. They will generally recover with little observable damage. Large shrubs may also bounce back well. Perennials will need to be observed for a while to see how they fare. Annuals will be the first to show stress, and the least likely to recover.
Vegetables and fruits are more susceptible to periods of water-logged soils. Neither appreciates wet feet for any length of time. Herbs are also resentful of wet feet as many originate in the Mediterranean and thrive in drier climates.
So going back to that question of what to do after the wet has passed; here are a few things you can do to help your garden recover:
Don’t work wet soil
Working wet soil can do long term damage to the soil structure itself. Soil particles can become compressed, increasing compaction and exacerbating drainage issues in the future. This damage is not easily or quickly repaired.
Allow the soil to dry out for several weeks. Push a trowel into the soil and wiggle it back and forth. If visible water is in the hole, or if the soil at the sides of the trowel looks glossy, wait a few more days.
When you do start working, use hand tools such as a spading fork. Using a rotary hoe at this stage has more risk of compaction than lightly cultivating with a fork. If you must till, save it for drier days ahead.
Don’t rush to replant
Soil biology is damaged when soils are water-logged for long periods of time. Soil microbes that require oxygen to live may die off and those that survive without oxygen may flourish. These anaerobic microbes cause soggy soil to have that foul, sour odour.
This imbalance affects the availability of nutrients for plant use. The soil food web needs a chance to recover. This can happen relatively quickly if the soil was healthy before the storm. If sufficient organic matter, nutrients and minerals are present, beneficial soil biology will re-establish itself once oxygen is available again.
If you must replant quickly in the vegetable garden, support the soil biology with added compost. Many seeds will have a tendency to rot in soggy soils. Even though you want to re-establish your veggies, you should wait until a ball of soil can be squeezed in your hand and no water drops can be wrung out. Like a damp sponge, moist but not wet.
Don’t rush to prune
Stress from water-logged soil may cause some leaves on fruit trees and herbs to yellow and drop off, but the branches are not necessarily dead. New leaf buds will begin to grow in a few days. Wait until you are sure there is die-back before you prune.
Clean up the fallen leaves and any foliage that is rotting. They can harbor harmful fungi and bacteria that could affect plants.
Heavy rainfall can leach nutrients out of the soil. A light fertilization will replace those nutrients. Don’t overdo it. It is better to fertilize lightly several times than to push plants that are recovering from stress. Foliar feeding with seaweed extract can quickly boost needed minerals to reduce plant stress.
Be prepared to deal with pests and disease
Water stress weakens plants. Weakened plants are susceptible to attacks. Fungal diseases are common after periods of heavy rain. Pull mulches back from the base of fruit trees, herbs, and vegetables until it dries out. This will decrease the opportunity of fungal disease spores to form and splash on leaves. It also helps the soil dry out faster.
Make an action plan
One of the best things you can do after a heavy rain is to assess your landscape. There is no better time to identify problem areas and form a plant to prevent future issues.
Get a clipboard and a camera or your phone. Walk the garden making notes and taking pictures of places where water stood for long periods of time. Use this information to help you make future decisions such as raising beds, improving soil texture, and making future plant selections.
Make a list of plants that seem more sensitive to wet soils.. If you have to replace plants, you may want to look for something better adapted to the possibility that it will happen again.
However like always if you’re stuck or would like further advice, come down and see us at Wingham Nursery and we’ll get you growing on the right track. Stay safe.
Wingham Nursery & Florist
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