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What should I know about watering plants in containers?
By Kerry Michaels, About.com Guide
Watering plants in containers doesn't sound like rocket science, but can make all the difference to the health of your plant. Here are 7 tips for watering plants in containers.
- Water Deeply - The most important thing when watering plants is to give them a good, long drink - optimally, until water runs out the hole in the bottom of your container. You do this because, depending on the size of your pot, many of the plant's roots will be down towards the bottom and you want them to be able to get water too. It will also encourage roots to grow down toward the bottom of the pot, which is better for plants.
- Check Moisture Level - Before watering plants, check to see if your plant really needs it - the top of the soil can look dry, even though just below the soil line it is still moist. Stick your finger into the soil all the way to the second knuckle. If it feels dry at your fingertip, your plants need water.
- Know Your Plants - Most plants prefer to live in moist soil, not wet, just damp. Fortunately with modern potting mixes, which are designed for good drainage, this is not impossible. However, different plants have very different moisture needs. Some plants like to be dry, some like to be a bit dry between waterings and then there are those princessy plants that, if they get even a little dry, will swoon and drop all their buds and leaves. However, as a rule of thumb, flowering annuals don't like to get too dry. Succulents like to be a bit dry and vegetables - particularly those that are juicy (tomatoes, cucumbers, melons) - like to be kept moist and need a huge amount of water. Some herbs (basil, rosemary, thyme, dill, oregano, cilantro) like to dry a little between watering and the flavor will be stronger if they do. Some herbs like (parsley, sage, chives) like more moisture. One way to keep track of your plants' watering preferences always nearby is to keep the plant tag, either under the pot or buried in the soil.
- Water in the Morning - According to Horticulture Magazine, plants' roots are more receptive to watering in the morning and the evening and less so in the midday sun. However, it's not a good idea (if you can prevent it) to water in the evening, because when you let water sit on the leaves overnight, your plant is more likely to contract some plant diseases, like mildew. That said, if you get home from work and your plants are dry, even if it's in the evening, give them a good long drink.
- Water the Soil, Not the Leaves - It turns out that some plants - ones with hairy leaves - are susceptible to sunburn if you get water on their leaves in the sun. Water droplets can act like mini-magnifying glasses and burn your plant. Even if your plant's leaves are smooth, it is still a good idea to water the soil and not the leaves, if you can. Wet leaves can lead to an increased chance of fungus, mildew and other diseases.
- Don't Rely on the Rain - Even if you think that a rain shower has watered your plants, check anyhow. Sometimes a plant's foliage and flowers can act like an umbrella and actually keep water from getting to your soil - shedding the moisture right out of the container.
- Don't Let Soil Dry Out Completely - Most potting mixes become tough and won't absorb water efficiently, if you let them completely dry out. Your potting mix can also pull away from the sides of your containers when it gets too dry, so while you may think you are giving your plant a good drink of water, the water may be just flowing over the soil, going down the sides of the pot and out the bottom, leaving your plant gasping for a drink. If you do let your soil dry out, you have a couple of options. If your pot is relatively small, you can take the whole thing and submerge it in a larger container of water, taking it out when it has stopped bubbling. For a large pot or one that is difficult to move, poke holes in the soil with a pencil or skewer, and then give it a good drink, making sure the water is penetrating the soil and not just flowing down the sides.
- Don't Assume Once is Enough - Depending on where you live, the size of your pots, and the kind of soil you use, don't be surprised if you end up having to water your container gardens more than once a day. Heat, wind and dry air can quickly parch your plants. Terra cotta pots, hanging baskets made from coir and metal pots all can dry our ridiculously fast on a hot, windy summer day. Over the season, you will probably get to know which containers need to be checked more than once a day, but when they are first planted, it's a good idea to check your containers in the morning and again in the afternoon.