"I have this giant philodendron plant which has outgrown its pot and even the doorway and is practically reaching my ceiling. It looks sad and needs help. Could I chop off the top and replant that? What can you suggest for me to do with it - and when?
Jean Konda-Witte Abbotsford
Philodendron vines are reputed to shoot back vigorously from hard pruning. They're even said to grow new plants from slices of stem.
So your idea about chopping off the top and replanting it might work, though you'll have to remove almost all the branches down to one or two leaves each because a plant with no roots won't be able to support a lot of green stem and leaves.
But for your large and very old plant, this would be an extremely stressful experience. You'd need to plant your philodendron's top in well-drained soil and water frequently, making sure it stays moist without sitting in water.
Since your plant is tropical and will be inside, I don't think the time of year will make a difference to pruning results. So fall or spring - it's your choice.
An alternative plan is cutting back some of the philodendron's long branches to fit your space better but leaving some green growth. The plant should respond by putting out new growth points on the stem and lower branches or as side-shoots on the leafy stems you left.
But before you make a major cut, why not make sure a young philodendron is waiting as a backup. Just take a couple of four or five-inch pieces, remove any leaves which would be in soil, apply rooting hormone in shallow slits near the bottom end and plant in potting mix. Keep the cuttings watered. They should root quickly.
As soon as they start growing, you're in a safe position to slice off your philodendron's head and replant it. Cutting her trunk down to a foot or so might also trigger new shoots.
"We had extensive landscaping done in February 2010 and mostly we love it. But not everything is thriving. Our Rudbeckia hirta has collapsed in the middle as though something squashed it. Now another clump has the same problem. Should I divide them?"
Jill McIntosh, Coquitlam
Yes, your rudbeckia should be divided. The middle is getting congested and the old roots there have become exhausted.
If not divided, it will eventually cease to flower in the middle. Many of the taller, mat-forming perennials need frequent division.
You should re-plant the vigorous shoots on the outside and discard the less-productive centre. This can be done in fall, but spring growth makes a faster start.
"I have some mallows which are infected by orange rust. Should I root them out after flowering?"
Kimie Takusagawa E-mail
Yes, do root them out. Don't compost them because that will only spread the infection.
Your mallows are probably hollyhocks. Hollyhocks are a type of mallow which is notorious for rust infections.
It would also be best to remove about an inch of the top layer of soil where the mallows were. Then mulch with new soil, compost or bark mulch.
This will help deter rust spores from re-infecting anything else that you plant in the same place. The Antwerp hollyhock is said to be resistant to rust.
. Anne Marrison is happy to answer garden questions. Send them to her via email@example.com