Plants are living things—and all living things will eventually stop living. The trick is knowing when your plant has either shuffled off this mortal coil or is going to, so you know to stop investing resources or risking nearby plants with something infectious. While a brown, withered plant in a dry planter is as close to DOA as the plant world can offer, it's not the only sign you should pull up roots and move on.
If your plant has turned brown and crispy, it’s likely time to call it a day. You can always try to drench the plant to give the roots a chance, trim back the brown leaves and see if, in a few weeks, any new shoots are produced. The roots are really the factor here. If the roots are moldy, smelly or slimy, the plant has gone to the other side. If the roots are just brown and dry, your plant could be dormant. To tell, scratch a branch or root and see if underneath it is green and damp. If so, that plant is on winter vacay and can come back in spring with adequate water, light and food. Plants go dormant for all kinds of reasons, but it’s usually environmental stress like cold weather or a lack of nutrients or water.
Since the weather is harder to control outside, you may lose plants, even large ones like shrubs, to extreme heat or cold. We experienced a freezing event this year that took out giant 20-year-old hydrangeas, artichokes and daphne, which I mourned. Heat domes can cause the same problems, and it’s not always likely you’ll see the results of these extreme weather events immediately. The plants may be dormant when the event happens, so you’ll only know when it doesn’t spring back to life in the warmer weather. If you’re in the prime season for a shrub or bush and it is still just brown and unproductive, it is reasonable to perform a scratch test on the bark to see if it’s still viable. If it is following a weather event, it’s likely not. In those cases, while the plant is not hurting anything by staying put, you’re missing the opportunity to replace it. Gardens are always changing. You can cut the shrub or bush at the ground, leaving the roots to decompose in the soil. Be sure to give the soil some food before you plant something new.
The other reason you’ll lose plants outside is disease like viruses and funguses—this is more problematic because it can spread, and in many cases, remain in the soil, where it will infect new plants. There are thousands of viruses and funguses in the plant world, some specific to a type of plant like peach leaf curl, and some which can affect a lot of different types like mosaic virus. Generally, the signs you need to look for are brown or black spots, brown or black ends on leaves or yellowing of leaves. Once that happens, you should immediately cut that vegetation away, using shears that have been sprayed with bleach solution or vinegar to clean them, and ensure you do not touch other plants with the clippings. Put them in a plastic bag and get thee to a nursery to ask what the problem is. Once diagnosed, you’ll know if it’s solvable with a fungicide or other treatment, or if these plants need to get pulled and go in the trash (not compost!). Again, this process should be done quickly—you will be less traumatized losing one tomato plant than all your tomato plants. You’ll also want to ask about how long to leave the soil or how to treat it so that it's safe to plant in next season.
By the way: For many nurseries, you can actually return a dead plant. I’ll admit, I have always found this practice somewhat mortifying, but now that I know nursery owners and workers, I have a different perspective. They encourage the practice because they’re invested in your garden for a lifetime, and it’s likely you’ll buy something else when you return the expired plant.
Trees are fantastic for shade, fruit, and natural habitat. They are not so good for staying up in storms, getting all the water they need, and being impervious to pests. Trees are expensive and can be dangerous when one is dying or dead—dead trees cause massive damage to structures and are a real threat to people, too. Unfortunately, treating or removing trees is also expensive, and could require permits.
First, examine the trunk of the tree. Look for splitting, cracks or peeling bark. These are warning signs. Are there mushrooms growing near the trees roots or trunk? That's a sign of decay. Finally, are you seeing many branches without any active buds during spring? You may have a dead tree, and that means you need to get a qualified tree trimming company to check on the health of your tree.
