Plants get thirsty as they grow

June 13, 2012 

Remember those potted and hanging plants that seemed to be more dirt than plants a month ago? Well, welcome to late spring and the ensuing growth spurt.

Right about now, your potted plants and hanging baskets are beginning to need more water because roots are filling up the container. More roots and less room in the pot means the soil has more trouble storing moisture.

If your soil feels dry when you plunge your fingers into the pot, add water until you see it run from the drainage holes. But first, a warning: If you notice hanging baskets with limp plants it could be due to too much water or poor drainage – check the soil before you water. Overstuffed hanging baskets in the sun, or heavy bloomers such as hanging petunia baskets, may need water twice a day during hot weather.

Here’s a tip for easier maintenance: Place a potted plant beneath your hanging baskets to catch the drainage water. This way you’ll be “potty training” your hanging baskets so they don’t leak all over the deck or patio.

Here are a few reader questions:

QI love the tropical look of cannas and always buy a few of these large jungle plants to use in the center of container gardens. I have noticed cannas growing in ponds and pots of water in magazine photos. My question is are these the same cannas as the canna tropicanna that I grow with good drainage in containers? I do have a small pond and would like to try growing cannas in the pond. J.M., Olympia

AWelcome to the water world because cannas are can-do plants that will adapt to life in the pond or water garden. First you need to repot your cannas into a plastic or clay pot lined with burlap or a thick layer of newspaper to block the drainage holes. Use a potting mix made for pond plants or make your own by using 20 percent potting soil and 80 percent sand. Mix this soil with water from your pond to make a thick “mud pie” in the pot. Then remove your potted canna from the original pot and rinse off the old regular potting soil before adding the fleshy bulb to the new pot with muddy soil. Leave 3 inches of room at the top of the pot and fill this with stones to keep the soil in place and weigh down the pot.

Now you can lower your newly potted canna into your pond or even a large water-filled container, using a flat rock as a base below if necessary to keep the rim of the pot just a few inches from the top of the water. Fertilize your canna monthly to enjoy the tall and dramatic blooms but use only fertilizer that has been made for aquatic plants. Never use regular plant food in a pond or water garden as this can encourage algae growth. Now you can even go on summer vacation and your underwater pond canna won’t be thirsty while you are gone.

QWe have a vacation house on Lake Chelan. It gets very hot and nobody is around to water the potted plants. Is there anything we can grow in pots that will survive without water for weeks at a time? T.N., Maple Valley

ASedums and succulents to the rescue. The fleshy leaves of golden sedum Angelina can act as a ground cover or trailing plant to be a spiller in a container composition while the tall upright form of sedum Autumn Joy can be used as the thriller or focal point plant. Add the new and improved Hen’s and Chicks or sempervirens as the fillers to fill up any open space in the pot and you’ll have a colorful and texture-rich planting that can go weeks without extra water. Sedums and succulents do best when partially shaded in hot summer climates and do appreciate a good soaking every few weeks after their soil is allowed to dry out. For more potted plants without the drama of drinking problems consider lavender, yuccas, rosemary and other Mediterranean herbs that adapt to heat and dry weather.

QHelp! We need instant screening from some new neighbors that have an upper deck right next to ours in our condo community. Problem is we have very little room as this deck is small and we are gone a lot and sometimes forget to water our plants. Yes, we have killed plants in the past but really need privacy and we need it very fast.

AHere’s the easy answer. Buy a roll of bamboo or twig screening from a home-center store and put up an instant wall of privacy. You can secure the screening material by placing a rebar stake at either end of the deck and secure the rebar right to the rails on the deck with duct tape or by using concrete mix in the bottom half of a pot to set the tall stakes of rebar into pots. You need enough tall rebar stakes to create a frame for the screen so that it will not fall forward in the wind. If there is a roof on your deck you may be able to secure the screen from the ceiling as you would a roll down shade. Sometimes the answer to instant screening is not plants – especially in a small space.

Marianne Binetti is the author of “Easy Answers for Great Gardens” and eight other gardening books. She has a degree in horticulture from Washington State University and will answer questions at her website

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