Q: A couple of months ago, I bought a neglected chaste tree in a 10-gallon container that was understandably on sale. Could you give me information on this tree, its growth habit, and whether it needs sun or shade?
A: You have a winner there. This species is called Vitex agnus-castus in Latin, but it’s also known as Vitex, chasteberry, or monk’s pepper. It grows to a height of up to 15 feet with bright blue blossoms.
To begin, prune your tree to about 18 inches and remove all dead wood. As you prune, the center of the branches should be green, which indicates that the tree is still alive. Remember that a chaste tree needs at least eight hours of sun in a spot where it can grow to its maximum height. It takes about five years for a chaste tree to mature, blooming in “heavenly blue” during the summer. You may also plant your chaste tree during the winter months, as long as you are able to work the soil. Select a sunny and permanent site, since it doesn’t like to be transplanted. Dig a hole that measures 18 inches deep and three feet wide. Remove clay and discard pebbles, then mix clay with organic-rich garden soil and some manure, blend it all together, and start filling the hole with this new blend. Place the tree in the middle of the hole, making sure that everything is level, then continue to add soil mix. Water thoroughly, then let nature do the rest.
Q: This is the first year I am attempting to winterize my mandevilla. Sometime in October, I moved the plant into my basement, which I think might be a good spot for it. Please advise.
A: As you probably know, a mandevilla is a tropical climber. The ultimate spot for winterizing it would be a heated greenhouse, but if you don’t have a greenhouse, you have to try to create a similar environment. So, let’s start by taking it out of the basement, which is the worst location for it.
Select the sunniest room with the largest window in your home, but away from heat sources. Then repot your mandevilla—ideally into a larger clay pot with ample drainage—and replace the old soil with rich potting soil. Once repotted, cut your climber back to about 12 inches, remove all dead plant materials as well as the old stake, if there is one. Then place a new stake among the vines and tie everything together with a piece of string. Make sure to keep the soil moist, but just barely, since this climber is in a dormant state and needs just enough of the proper care to sustain itself.
Q: I have dozens of miniature crocuses that I want to force into blooming indoors. But I’ve noticed that they’ve started sprouting in the bag. Does this mean I’ve kept them too long?
A: To check whether your crocus bulbs are still viable, squeeze them: If they’re still firm, you’re okay. What’s needed is a cool room with a sunny window, or at least a spot where the sun hits for several hours a day. Select a container, fill with potting soil, and press your crocus bulbs in, pointed end up, but leave the sprouting tip exposed. Plant them tightly together, then water sparingly. Drainage isn’t an issue, since watering will always be slight, but should take place two to three times a week. Your crocuses will begin to bloom within six to eight weeks of planting.