Q: I followed the instructions that were in the paper a few weeks ago, and planted an amaryllis bulb and paperwhites. The paperwhites have stems...

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Q: I followed the instructions that were in the paper a few weeks ago, and planted an amaryllis bulb and paperwhites. The paperwhites have stems about 6 inches high, but the amaryllis is just sitting there. Nothing is happening. I was hoping it would bloom for Christmas. What’s wrong?

A: Nothing is wrong, it’s just that paperwhites are much easier to nudge out of dormancy than amaryllis. You can jump-start the amaryllis by giving it some heat. Place the pot on top of the refrigerator or another warm — not hot — spot in your house until it sprouts its fat stem.

Don’t over-water; once a week should be plenty. Take comfort from the thought that although the amaryllis may take longer to bloom, it’ll flower in January when the paperwhites are just a memory.

Q: I’m a professional gardener, and live on Hollywood Hills in Woodinville. Many of us have tried to get rid of the English beauties for which our hill is named, because of the prolific seeds. I have long wondered if the many selected varieties of holly are as harmful as the common English. For instance ‘Blue Boy’ and ‘Blue Girl,’ which are widely available at wholesale and retail nurseries, and are very cheap at Home Depot! Are these holly varieties safe?

A: The common English holly (Ilex aquifolium) is promiscuously invasive, but that doesn’t mean all hollies cause problems. According to Dr. Sarah Reichard, at the University of Washington Botanic Gardens, the holly-cultivar question is a thorny one that even the experts aren’t sure about.

“In some cases, there can be a cautious, qualified yes. For example, most (but not all) variegated cultivars are not invasive,” says Reichard. She offers the guideline that if the cultivar is less vigorous than the species, with fruit that’s less attractive to birds, then it’s probably OK.

The problem is that invasions start slowly, and most of the cultivars haven’t been grown long enough to be sure just how invasive they really are. However, that could be said about a great many of the ornamental (non-native) plants we grow in our gardens.

Q: The more I read and practice mulching, the more confused I get. I have a mixed herbaceous perennial garden with many woodland plantings. The last mulch I put down was a mixture of fine bark and steer manure. But I’m experiencing fungal diseases and whitefly on many of my rhodies. Would compost first, then a layer of fine bark be better?

A: You’re wise to be cautious, as mulches can cause problems as well as greatly benefit a garden. So much depends on the composition of your soil, the kind of plants you’re mulching, and how the mulch is applied, as well as what the mulch is made of.

One of the main reasons to mulch is to liven up the microbial activity in your soil, so be sure that any mulch you choose contains aged manure. Chicken manure is the best kind for plants, followed by cow, goat and horse.

To prevent rot, pay close attention to the instructions to keep mulch a few inches away from the stems, crowns and trunks of plants.

For detailed mulching instructions, take a look at the local utilities Web page, www.savingwater.org. Click on “Outside of your home” and then “Build healthy soil.” You’ll find a thorough article including comparisons between different kinds of mulches, and suggestions for which kinds of plants do best with which kinds of mulch.

Valerie Easton also writes about Plant Life in Sunday’s Pacific Northwest Magazine. Write to her at P.O. Box 70, Seattle, WA 98111 or e-mail planttalk@seattletimes.com with your questions. Sorry, no personal replies.