Perennial Garden Care

Red Lillies

Here are some tips on how to take care of your perennial garden.

  • Loose, well-drained, loamy soil to which compost has been added is ideal in most regions.
  • Fertilize with low-nitrogen, high-phosphorus fertilizer. Most perennials do not need heavy fertilization. A single application in spring (after the soil has warmed) is usually sufficient.
  • Water deeply, especially during the first growing season. The soil should never be overly dry or wet. Avoid getting water on the foliage to avoid disease.
  • Group plants that have similar water requirements.
  • Mulch around plants to keep weeds to a minimum and retain moisture.
  • Create a neat, clean edge between your lawn and flower bed. Use an edging tool or install permanent edging.
  • Remove spent flowers to prevent plants from using their energy on seed production and to stimulate reblooming.
  • Put plant supports in place early in the season, before plants get too big.
  • Divide big plants when they are not in bloom. Spring and fall are usually the best times to do this.
  • If your ground freezes, cover all your perennials with a protective mulch of compost or dry peat moss.
  • Leave mulch on your perennial beds while ground is frozen until there comes several nights in a row with above-freezing temperatures. As you remove the mulch, add it to your compost pile.

In our region, where temperatures can dip, we have found a technique that allows the tougher perennials, such as alpines, to overwinter right in their pots.

  • First, we cover the pots with Microfoam, a ½-inch-thick white foam blanket with plastic backing on both sides.
  • Then we scatter a thick layer (about 6 inches [15 cm]) of loose peat moss onto the blanket and put another layer of clear plastic on top. Microfoam is a commercial product not generally available to home gardeners, but by substituting several layers of white spun fabric such as Remay, available at most garden centers, you can create the same effect.

Most containers don’t have enough soil volume to insulate perennial roots from freezing when winter temperatures drop. Two or three weeks prior to freeze-up, transplant into the garden any perennials growing in all but large containers.

Reader Comments

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What about Hydrangeas Cut

What about Hydrangeas Cut back or no ???


I have a Rosemary plant in a large pot that I have had for years. It has spent winters facing north and now, facing south. Last year we had a horribly cold, freezing now and ice winter.

My Rosemary has never been damaged. It is about 4 feet long in the pot and covered with flowers. I planted one in the ground right beside it last spring and same goes for it! Very healthy! The one in pit gets water when I happen to think about it.

winterizing my plants. help please

I just planted several perennial mum's and am not wanting them to die what should I do about the frost and the winter time?

It’s important that the soil

It’s important that the soil around the mums is well draining. If not, water will freeze to ice around the roots and kill the plants. After a couple of frosts cut the stems back to 3 to 4 inches. Add mulch around the plants after the ground is frozen. Leaves or straw work well.

Hi, I have a question or two.

Hi, I have a question or two. . . I have Roses that were ordered and sent. I left them in the package and put them in the fridge because the package said perishable. But I want to know when I can plant them. . . I heard that it is good to plant them after the full or new moon. The Full moon was on May 4th and the New moon is May 18th. Please help. Is it too late for me to plant them? I also want to know about my tomato plants which I have planted in pots. . . I think one is drowning. . . I think it should go into the ground, it is about 10 in. tall or so. I don't want it to die. The other two are doing O.K. I think they should be planted in the ground too. Help. Thank you.

Hi Teresa, Plant the roses

Hi Teresa,
Plant the roses after May 18 when the Moon is waxing (when it is between new and full). Plant the tomatoes in the ground if outdoor temps. are warm enough and you don't have any cold nights.

When should I plant perennial

When should I plant perennial Delphinium in Charleston, S. C.?

Hi Shirley, Plant the

Hi Shirley,
Plant the delphiniums i early spring when the soil has warmed up a bit. See our delphinium page for more advice.

I'm planning on planting 400

I'm planning on planting 400 tulips in SE Wisconsin, zone 5A this November 8 and 9. I realize prime season was 3 weeks ago. The forecast is calling for 27 nt, 38 during day. What are risks associated with planting this close to heavy frost/freezing? If it's too late, how can they be stored for next season?

Thank you,

You can plant the tulips as

You can plant the tulips as long as you can dig in the soil. The ground is not going to freeze for some time. They will be fine during the cold winter months and will start growing as soon as the weather warms up a bit in the spring. 400 bulbs!! Wow!