Container plants need extra care in summer

Container plants are much more vulnerable to the devastation of summer heat and sun than those planted in the ground. Therefore, you need to provide special care to help them survive -- and more importantly thrive -- during the dog days of summer.

Location: Where you place container plants is very important. Provide some protection from afternoon sun for those grown on patios or entryways. Protection may be shade from house walls or overhangs, from privacy walls or fences, or from shade trees. Most plants thrive where shifting shade provides protection for the afternoon hours. Also, think about moving pots to temporary locations during the heat and then move them back in the fall.

Morning sun is best for flowers and vegetables planted in pots. Most general references for these plants call for a minimum of six hours of direct sunlight. However, our sunlight is so intense that bright indirect light usually is sufficient to encourage good flowering and fruiting.

Irrigation: In addition to the appropriate location, the amount of water that container plants need also is critical. This is because air circulates around and the sun shines on container sides, so the inside soil dries out rapidly, especially with temperatures exceeding 90 degrees. You may need to water twice daily if plants are in full sun with temperatures now more than 100 degrees.

It is a must to water small- and medium-sized containers with such a small volume of soil daily, because they can't hold enough moisture during dry weather. Larger, barrel-sized containers may go a day or two between waterings. You'll know how often to water by the appearance of your plants; if they wilt between waterings, water more often.

Always water enough to thoroughly moisten the soil from top to bottom. Let the water running out the drainage holes be your signal to stop watering.

Easier watering: Invest in an automatic watering system, especially if you have several potted plants; it's easy to forget to hand water. You'll find battery-operated timers at garden supply stores. They easily connect to a water faucet and irrigation tubing.

Select drip emitters in pots based on pot size. Use higher volume drip emitters on large containers and lower volume ones on small pots. This will allow for more consistent watering when all the pots are run off of a single irrigation line.

Water time: Remember to water at night or in the early morning. Water coming through a very hot hose during the middle of the day can damage plants.

Hydrophobic: Sometimes container soils become hydrophobic. That's when potting soils dry out and actually repel water. When this occurs, you may think your pot is accepting water, but it is simply running around and down the edges of the soil and out the bottom of the container.

To correct this condition, add a few drops of liquid dishwashing detergent to a gallon of water and irrigate slowly. The soap breaks the barrier so your soil can absorb the water. You don't need to do this again, unless the pots dry out.

Saucers: You don't want pots sitting in saucers. Drainage water collects in them and salts concentrate, allowing them to reabsorb back into plants, causing damage. You'll also find saucers can be a haven for ants to nest. Elevate your containers with bricks or the like to prevent these problems.

Lining pots: Here's a way to keep moisture from seeping out of clay pots: Line them with plastic before planting. These liners will drastically reduce moisture loss from potted plants as compared to unlined clay pots. Trash bags, whether they are black, white or brown, make ideal liners because they come in a variety of sizes. Just be sure that after you've placed the bag in the pot, you poke holes in it to line up with drainage holes in the bottom of the pot. After filling the pot with soil and planting, trim off the bag top to conform to the rim of the pot.

Another advantage for using plastic liners is that they'll prevent salt stains from forming on the outside of the pot. Salts in water build up, causing a white staining on the outside of clay pots.

Mulch: To conserve moisture in pots, cover the soil with mulch. The best mulch for containers is a fine bark. Blanket the soil with an inch of mulch, which reduces evaporation, moderates soil temperatures and reduces moisture fluctuations. Whenever you're potting plants, always leave room at the top for mulch.

Feeding: Finally, to keep container plants healthy, fertilize regularly. For best results, fertilize flowering and fruiting plants with a liquid solution such as Miracle-Gro every two weeks and leafy plants monthly. Las Vegans have to fertilize more because we have to water so much that it leaches the nutrients away.

One of the best ways to fertilize container plants is by using a timed-release product such as Osmocote. These products come in various release times for as long as a year. These kind of products can really save you time. Gear the product to what you are growing. For flowers and vegetables, use a three- or four-month release fertilizer. For long-term plants, such as perennials, herbs or shrubs, use longer lasting formulations.

Plants will need the full complement of macro and micronutrients. If you are fertilizing leafy plants, select a fertilizer high in nitrogen. For flowering plants, choose one high in phosphorous.

IRIS SALE

This is your last chance to get award-winning irises and lots of new varieties with many unique colors to add new dimensions to your landscape. The Southern Nevada Iris Society is having its annual iris sale from 8 a.m. to 5 p.m., or until supplies run out, today at Star Nursery, 8725 S. Eastern Ave. Society members will be on hand to help you be successful in growing your new irises.

TROUBLESHOOTING PLANT PROBLEMS

What are some flowers we can add to our landscape that will take the summer heat? Why are the leaves on my olives turning yellow and dropping? Why won't my figs get any bigger than a marble? We are following the guidelines in watering our lawn, so why is it still drying up? These are just a few of the questions I will attempt to answer at 8:30 a.m. Saturday as we tour the gardens at the Springs Preserve, 333 S. Valley View Blvd. Call 822-7786 for reservations. Bring a hat and water.

The Springs Preserve's eight-acre botanical garden and gardening exhibits through the site will inspire you. All educational classes highlight water-smart landscaping, gardening for small spaces, organic gardening and cultivating your own farmer's market. Come get your hands dirty, along with ideas to improve your landscape.

Linn Mills writes a gardening column each Sunday. You can reach him at linn.mills@springspreserve.org or call him at 822-7754.