GloucesterTimes.com, Gloucester, MA

July 26, 2013

North Shore Gardener: Cultivating hibiscus on the North Shore

North Shore Gardener
Barbara Barger

---- — Q: I purchased two hibiscus trees this year and placed them on my hot, sunny decks. One of them has lots of flowers, but each day more and more leaves turn yellow and fall off. It’s starting to look like there will be no leaves left soon! The second hibiscus has no flowers and the same problem with the leaves. What do I do? I am starting to panic, as they looked so pretty on the decks, and I really want them to live. I was hoping to be able to bring them in for the winter.

A: Hibiscus trees or plants aren’t the easiest plants to grow in our climate — even indoors. Let’s start with the pots on the deck; a perfect place for the tropical plant, assuming there’s sun all day. You brought them home from a greenhouse or an indoor shop and you don’t know how they were cared for, so now it’s all up to you. The hot weather is perfect for them — keep them well watered. If the plant has more than a few leaves that are yellowing, a bug may be the suspect, so get out the garden hose. Spray every leaf on every side, every week or two throughout the summer. In the winter, put the plant in your shower every week or two; spraying will knock off any bugs and raise the humidity.

Fertilize the hibiscus regularly when it’s growing. Remember that a hibiscus plant blooms on new growth; trim gently when necessary. In late summer, plan to bring the plant inside next to a very sunny window, but even this might not be enough sun; artificial light may be necessary. Summer or winter, never allow plants to stand in water.

Q: One of my favorite things about summer is my endless blue hydrangeas. This year I have lots of blooms, but they are smaller than usual. I admit I did not fertilize it, but could that be why the flowers are so much smaller?

A: Yes, it may be the lack of fertilizer, but also the type used. Feed the plant with a low-nitrogen fertilizer. To make it easy for you and the plant, use a time-release, all-season fertilizer or a slow-release fertilizer, like Osmocote. You may be able to make the flowers larger by the end of the summer, but you may have to wait until next year.

Q: I am writing to get some guidance on a pine needle Christmas tree (evergreen). The tree is part of the house and is very tall and getting bigger each year. It has already overtaken our hydrangea bush and is making the pathway between our holly bush and the Christmas tree smaller and smaller. Can we trim the branches? It is too tall, so we would not be able to reach the top. Or should we hire someone? And will the service of a landscaper be suitable? Your advice, suggestions and knowledge are greatly appreciated.

A: Yes, you could certainly try trimming the branches, but remember I said “trim.” You didn’t say what kind of evergreen, but almost all kinds of evergreens are bought for their beautiful shape. Keep that in mind — you don’t want to ruin it by over-pruning.

If the budget allows, a professional tree company could do the trimming, top to bottom, in less than an hour. Or, the most costly way to handle the tree would be to have a tree company dig and replant the tree, then replace it with another species. You’d have some guarantee on the work.

This week’s dirt: Do you have some plant cuttings sitting on the windowsill and just turning to mush? Some plant cuttings, like rosemary, are difficult to start. Try using a green glass container instead of clear glass. I think you’ll see a difference.

---

North Shore Gardener by Barbara Barger is a Beverly resident and a frequent Times columnist. Reach Barbara by email at nsgardener@comcast.net or write to her c/o the Gloucester Daily Times, 36 Whittemore St., Gloucester MA 01930. Previous North Shore Gardener columns can be found at www.nsgardener.com.