Q: My Christmas cactus has run out of space in its pot. It needs watering every day. When I lifted it out of the pot and looked, there was no dirt, only roots. Is it okay to move it to a big pot? I don't really want a giant plant.
A: You have two choices, and either will make the cactus happy. If its location permits a bigger pot, that will succeed. Be sure to move up only one pot size. No Christmas cactus likes its roots to have extra space. If you have an empty pot that will give half an inch of fresh dirt at the bottom of the root ball and half an inch around the sides, that would be perfect. Change pots.
If you prefer not to have a bigger pot where the Christmas cactus now lives, prune its roots and put it back in the same pot. As far as I am concerned, this is the best method. It is how I repot my Christmas cacti every few years.
Working over the compost bucket or a piece of newspaper to decrease the mess, turn the cactus out of its pot. With a sharp knife cut half an inch from the bottom of the root ball and half an inch all the way around the sides. Put a corresponding half inch of fresh potting soil in the bottom of the pot. Set the cactus back in, and fill the gap around the sides with more fresh soil. Make clean cuts, and do not pull any roots loose. As soon as the roots meet fresh soil, the cut ends will begin growing into the empty dirt. If the idea of cutting on the roots worries you, remember that it is the plant equivalent of a haircut.
One caution: before you do anything, make sure that your Christmas cactus is not already showing the first tiny flower buds. This is the time of year when some are beginning the flowering cycle. If you see any buds, do not ask the plant to grow roots when it is trying to grow flowers. Save the repotting for a couple of months; do it as soon as flowering has finished.
Q: What should I do with my lavender plants in the garden? Will they live through the winter?
A: If they are English lavender, most varieties will live. The tag may label them as such, or may call them by their botanical name, Lavandula angustifolia. All other kinds of lavender are native to southern Europe; they are annuals here except in sheltered microclimates. If you are lucky enough to live in one of them, a tender lavender may survive.
If you have English lavender, I recommend cutting off the dried flower stalks but leaving all the foliage. The seeds will have scattered on the ground by now and will start some new plants next spring without any help from a gardener. To keep lavender in your garden for many years, don't be too neat. Let the seeds fall where they may, and compost the flower stalks so that seeds in the compost will eventually reappear. Even in the best conditions, lavender plants are short-lived, but old plants will be continually replaced by seedlings.
Q: Although my bean plants produced a good crop this summer, toward the end of the season there were a lot of brown spots on the leaves. What would have caused them? Should I worry about next year's beans?
A: Of the myriad causes for brown spots on leaves, two are reasonably common. If irrigating water comes from sprinklers, on any hot day the water in a sprinkler riser or a hose can get very hot. When the hot water first sprays out, the first drops will scald little spots on leaves. They become obvious a day or two later as brown freckles, and the spots will enlarge as the leaves grow.
Also, there are many different leaf spot diseases, all of which are caused by some kind of fungal infection. I know of none that does more than make bean leaves look ugly. There is a rust which affects bean leaves, but it is problematic only in rainy climates. If it has appeared in western Montana, I have not seen it. To be completely safe, I would not compost spotted bean leaves. Otherwise I would do nothing, and I would not worry about next year's beans.
Master gardener Molly Hackett, whose motto is “Never trust a gardener with clean fingernails,” welcomes your questions. Send them to 1384 Meridian Road, Victor, MT 59875; call 961-4614; or email firstname.lastname@example.org. Please include a garden-related subject line in emails. Hackett writes a twice-monthly Dirty Fingernails opinion piece for the Missoulian.