It's nice having flower-filled containers on our patios, decks, and balconies. They add a refreshing touch of color and life to areas where we spend our outdoor time. Right now they're probably looking lush, colorful, and healthy. But as summer progresses and the weather warms, container plants can become stressed from too little water, too much heat, not enough nutrients, or insect infestations.
Here are some ideas for keeping your container plants looking great and staying healthy all summer.
Water. Nothing kills a container plant faster than a lack of water. As the weather heats up heading into July, containers that might have needed watering once every few days now need water every day. Small containers may even need watering twice a day. It's a chore, but it's also an opportunity to enjoy your plants, and check in to see what they might need.
The need for consistent water is one reason why gardeners are advised to err on the side of a larger pot rather than a small one when choosing containers. Adding a layer of mulch over the top of the soil helps keep it moist and reduces the need to water.
If a plant dries out so much that the soil pulls away from the sides of the pot, there's still a chance to save it. Watering from the top will just send the water pouring through the sides, leaving the soil mix dry. Put the pot in a bucket or bowl with enough water so it comes halfway up the pot. Let it set for at least an hour. The water will wick up from the bottom and saturate the soil. The plant's leaves should rehydrate in a couple of hours.
If plants dry out repeatedly, even if subsequently watered, they can be permanently damaged. Growth, flowering and fruiting will be affected. Don't let plants dry out so much that you are constantly rehydrating dry soil.
Keep them cool. Consider moving heat-sensitive plants – those that wilt by the end of the day, even when they've been watered – to a place out of the direct afternoon sun. This is especially important if they are sitting on asphalt or pavement, or near a material that reflects heat, like metal siding.
Group plants together rather than spreading them out. It not only looks nice: the plants provide shade to each other, and it raises the humidity around them.
Metal and black plastic containers in the sun can get hot and heat up the soil. Metal containers can get so hot that they fry a plant's roots. Save metal containers for plants that won't be in direct sun all day. Or pot up a plant in plastic and use the metal container as a cachepot.
Deadhead or pinch. An annual plant's mission in life is to set seed. Once it has fulfilled its biological imperative, flower production slacks off. So to continue to get flowers, snip or pinch off any fading blooms before seeds start to form.
Petunias and calibrachoas can get leggy. Cutting back the foliage by about half will spur new growth. All plants benefit by taking off any dead leaves. It keeps plants looking neat and avoids spreading disease.
Fertilize. Plants in pots need to be fertilized more often than plants in the ground, because watering flushes nutrients out of the potting soil. Even if you are using potting soil with fertilizer already in it, or mixed granular fertilizer into the soil when planting, plan on feeding your plants every two weeks or so with a balanced fertilizer diluted to half strength.
Overfeeding, however, can make plants leggy and floppy, plus produce so much succulent foliage that it becomes a magnet for insect pests. Which brings us to…
Watch for bugs. If you've been paying attention to your plants, then you'll catch any insect infestations early. Aphids, spider mites, fungus gnats, scale and caterpillars are all potential problems. Figure out which pest you have before treating your plants, so you can choose the least-toxic method. Insecticidal soaps are often all you need to take care of pests on container plants.
Hand picking caterpillars and washing off spider mites or aphids with water or a wet paper towel usually takes care of the problem. If scale isn't too bad, wiping with a cotton ball soaked in alcohol should take care of it. Remember to check the stems and the undersides of the leaves as well as the tops, because lots of pests like to hide there.
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