Garden Answers

Bulbs

When can I cut the tops off and transplant irises?
Which bulbs need to be dug up and stored over winter?
Can I still plant bulbs in late Fall?
How do I plant bulbs?
What does it mean to force bulbs? And when should I plant garlic?
What is "dividing" of irises and daylilies?
Can I cut the ugly foliage from my bulb garden?
Is it possible to save my forced bulbs for next year?
How do I plant and care for Hyacinth?
What should I do to get my amaryllis to bloom a second year?
When can I cut the stems off my spent tulips?
Should I water my bulbs through winter?
When should I dig my dahlia bulbs and how can they be stored through winter?

Question: When can I cut off the tops of my Irises and when can they be transplanted?

Answer: There are a couple of options for trimming back your Irises. Some people like to trim back the foliage of their Iris this time of year. When they do, they don't cut them back all the way, just by a third or even up to one half. I personally don't like doing that unless you're digging up the plants to divide them for replanting. I leave my Iris alone and cut the foliage off when it dries late in the Fall. The way I figure it, the plant needs that foliage to produce carbohydrates for the winter, and I don't like interfering with that.

As for transplanting your Irises, now is the time! If you're transplanting DO cut the foliage back by half and remove any dead foliage. Carefully dig out the entire clump and pull or cut the plants apart, being careful to keep as many roots intact as possible. Cut out and discard any dead, soft or dried up rhizomes. Make sure to keep the roots moist while you're working with them. Preparing the soil will help insure an easier time for your transplanted iris, so be sure to work compost or some other decomposed organic matter into it . Doing this will help with both the drainage and aeration (which we certainly need with our clay soils!). Re-space the plants and plant them at the same depth. Water your newly planted Irises well, and you're all set for next year!

Back to the top.

 

Question: Please tell me all the bulbs that need to be dug up and stored over winter here.

Answer: As for the bulbs that need to be dug up and stored over the winter, there are a number of them. Most of the bulbs sold and planted in the Spring fall into this category. Dig bulbs like Gladiolus, Dahlias, Cannas, Calla Lilies, Freesias, Ranunculus, some Anemones, Begonias, Caladiums, Elephant Ears, as well as a number of lesser known bulbs. Their storage requirements may vary; you might want to check into a book on bulbs for help (we have some here at the nursery for you to look at) or contact the Extension office (244-1834) for some fact sheets on it.

Back to the top.

 

Question: I have some bulbs I'd forgotten about that I want to plant. Can I still do that this late in the Fall?

Answer: First, check your bulbs to make sure that they're okay. They should be firm. If they're soft and mushy or dried out, throw them away. If your bulbs are okay, it's really kind of late for planting bulbs. Bulbs need to do some growing in the fall before it freezes up for the winter. They root out and start sprouting, though they usually don't emerge from the soil. Denying them this "head start" can sometimes screw up or even kill the bulb. Most bulbs survive, though they may not bloom for you this spring, or the blooms may be malformed or much smaller than normal. These effects are usually limited to this year, next year they should be normal.

So, after all of that discouraging news, I would plant them outdoors as soon as you can work the ground. The earlier you plant them, the better off the bulb will be. You may lose some, and the others may behave a little strangely this year, but in the long run, they'll be okay.

Back to the top.

 

Question: I love bulbs, but I always forget to plant them. Not this year! I'm ready to plant. I just don't know how. Can you tell me?

Answer: Sure! You'll be so glad you remembered next spring when you have clusters of bulbs dotting your flowerbeds. But I'm getting ahead of myself. Let's start at the beginning.

You can achieve two months of blooming with bulbs, if you plan carefully. Bulbs, like tiny crocuses, start blooming in late February to early March and go until the giant allium blooms in mid-spring and stands five to six feet tall. All you need to know to plan a continuous stream of blooming bulbs is on their labels. They'll tell you when each bulb blooms.

Choose a place in your yard that's sunny to plant your bulbs. They need at least a half a day of sunlight to bloom well. Early blooming bulbs can be planted under deciduous trees (trees that drop their leaves in the winter), because they will bloom before the trees set new leaves. Also, plant bulbs for major impact by placing them in high visibility areas, like entryways, patios, and walkways. Perennial beds are great places for bulbs. They'll provide foliage and color while perennials are just getting started. If you want to make a big impact with bulb color, use lots and lots of bulbs. That way you won't be disappointed.

Bulbs love well-draining soil. We don't have any of that in Western Colorado. We have impervious clay. No problem! We can make it better for bulbs by amending it with well-aged, decomposed organic matter. Don't use manure, because bulbs are very sensitive to salts. Good choices are peat moss, soil pep, and Eco Compost.

Bulbs look their best when planted in a clump, so you'll be digging a common hole for each type of bulb you plant. The diameter depends on the number of bulbs you're planting. Bulbs are spaced their diameter apart in the hole. Dig the hole to the depth the label suggests planting. Then dig it another eight to twelve inches deep. Mix the organic matter with the soil from the soil half and half. Replace the amended soil in the hole to the depth of planting. Firm the soil in the bottom of the hole. Place the bulbs in the hole with the pointy end up-generally. It's impossible to tell which way is up on some bulbs. You can look for remnants of last year's roots for a clue. That won't work for anemone bulbs, however. They look like a wad of black chewing gum. Don't worry. Bulbs will find their way to sunlight.

Cover the bulbs with the amended soil and water them well. You're done for now. If we have an unusually warm fall, check the soil moisture occasionally. You may need to water them again. Cover your bulbs with a layer of mulch after the ground freezes in late November to tuck them in for the winter. Now for the hard part-waiting for spring and your glorious bulbs.

Back to the top.

 

Question: I have several questions about planting bulbs. What can I plant now for the spring and what does it mean to 'force' bulbs? Also, I've heard that this is a better time to plant garlic than in the spring. Is that right?

Answer: Fall is the time to plant Crocus, Narcissus (Daffodils), Fritillaria, Muscari (Grape Hyacinth), Hyacinths, Dutch Iris, Allium (Flowering Onion), some Anemones, and, of course, Tulips. Usually you can pick up individual tags with each type of bulb which will tell you how deeply and far apart to plant. It's also a good idea to amend your soil before planting your bulbs. It's important to do a good job of amending the soil before planting your bulbs since most of them prefer well drained soil. Mix in a low salt decomposed organic material like Soil Pep, Compost, or Peat Moss into the soil. I like mixing it half organic matter and half soil. Be sure to mix it in well below when you're going to be planting your bulbs. You want nice soil for the roots of the bulbs to grow into and you want water in the soil to drain down past the bulb. You can also mix in a little fertilizer at planting time. Lots of folks like to use either Dutch Bulb Food or Bone Meal to help their bulbs along.

Forcing bulbs is a way to add a little indoor color through the winter months. There are two different groups of bulbs that can be forced: those that need no pre-treatment, and those that will have to be chilled. Paperwhites and Amaryllis don't need any special care. Paperwhites can be put pointy side up into shallow pots with water and rocks. Amaryllis bulbs are planted in a deeper pot with soil, making sure to keep the neck of the bulb above the soil.

If you plan to force Hyacinths, Narcissus, Tulips, and Crocus, they all need to be chilled as part of the forcing process. I think the Hyacinths and Rock Garden Narcissus are best because they look fuller, staying low and bushy, and will maintain their blooms for a week or two. Each of these needs to be chilled 12-14 weeks, so planning ahead is essential! The first three weeks can be without soil, but after that, you need to pot them and put them in the refrigerator or an unheated garage. I usually water them a couple of times during this time, but that varies with different refrigerators. After the 12-14 weeks is up, put them in a warm area with bright light. It's important that the area has lots of light so they don't get leggy. Once they set flower buds, you can move them to where you want to enjoy them.

Yes, fall is a good time to plant garlic. It does best if planted 4 to 6 weeks before the ground freezes. This allows the plant time to develop good roots, while keeping it from generating leaf growth. Garlic won't do well if waterlogged, or if the soil is compacted around the bulbs. Since we have clay soils here, it's best to amend the soil BEFORE planting the garlic. Soil Pep, bark mulch, or peat moss should work just fine as I mentioned before.

Once you're soil's ready, break the bulb into individual cloves and plant only the larger ones (smaller ones can be used in your kitchen) as those will yield larger bulbs. For regular garlic, plant the bulbs 2"- 4" deep and 6" -12" apart and lightly mulch over the top. If planting elephant garlic, plant is 4"-6" deep and 12" apart. Hope this helps.

Back to the top.

 

Question: My neighbor asked me if I was going to divide my irises and daylilies. What is she talking about?

Answer: Occasionally dividing and transplanting perennials keeps them healthy and vigorous, which means better blooming. A typical perennial gains girth by growing new roots and stems, usually around the outer perimeter of the plant. Every 3 to 5 years, the clumps get too big for their space. Most perennials are divided in late September to early October. But now (late August to early September) is the time to divide your irises and daylilies.

Start by cutting back the foliage by half and removing any dead foliage. Carefully dig out the entire clump. Pull or cut the plants apart, being careful to keep as many roots intact as possible. Don't let the roots dry out while you're working. Keep them moist. Before replanting the plants, it's important to prepare the soil. Work a compost or decomposed organic matter into the soil to improve its drainage and aeration. Re-space the plants and plant at the same depth. Water the newly planted irises and daylilies well. You're done.

Back to the top.

Question: All that's left of my beautiful spring bulb garden are the leaves. Can I cut the ugly foliage off yet?

Answer: You'll be disappointed in your blooms next year if you do. The plant needs the foliage to build up the bulb for next year's bloom. You can tidy the plant a bit by removing the flower stem. Wait until the foliage is yellow and dry-about a month from now-to cut it down to the ground. Some folks like to braid the foliage, but it's a bad idea. The braiding damages the vascular tissue, hindering the plant's ability to prepare for next year. Now that your bulbs are done blooming, it is time to fertilize. Just sprinkle with Dutch Bulb Food and water in.

Back to the top.

 

Question: My forced bulbs have just stopped blooming. They were beautiful. Is it possible to 'save' them for next year? The one garden book suggested they be thrown away when finished blooming.

Answer: It is difficult to save paperwhites from year to year unless they have have been treated in a specific manner during the forcing process. The problem is that most people force their paperwhites in water. This works fine for getting and enjoying the blooms, and it's kind of interesting seeing the roots growing in the water. The problem is that water doesn't provide the nutrients that the plant needs to build itself up for the following year. The plant has been growing and blooming from stored reserves of energy built up last year. The upshot is that the bulbs need to have been planted in potting soil. This provides an environment that can support longer term plant growth and where you can fertilize them with a houseplant type fertilizer like Miracle Grow. I suppose you can try to grow them hydroponically, but that is a difficult process, requiring specialized fertilizer mixes and the know-how of how much and when to feed them.

If the plants have been growing in water, transplanting them now into potting soil usually doesn't work because the shock of the transplanting interrupts the ability of the plant to build up its reserves at a critical moment. If it was me, I'd throw away the bulbs this year. It just isn't worth the time, expense, and effort to save them. Next year, plant them in a good quality potting soil for the beginning , and treat them like a houseplant. They need very bright light to grow well. Fertilize them regularly, especially after they're done blooming. Cut the flower stalk off when the flowers have dried up, but leave the foliage! In a month or two, the foliage will start dying off. Once it has completely dried, cut it off, unpot the plants, and store the bulbs in a cool, dark spot for replanting in October or November. Hope this helps. By the way, thanks for the kind words about the column.

Back to the top.

 

Question: I need information on the planting and care of Hyacinth plants.

Answer: True Hyacinths are bulbs that are planted in the Fall. If you're thinking of planting some, come see us in late September. Like most all bulbs, they prefer well-drained soil. You'll want to amend that heavy clay in your yard with a good amount of low-salt organic matter. I like to dig a fairly deep hole (12"-16"). I mix the soil that I've taken out of the hole half and half with the organic matter. I like to use a mixture of peat moss and Soil Pep. Fill the hole in and gently firm it until you can place the bulbs on it at their proper depth (4"-6"). Cover the bulbs with any amended soil, water in well, and cover with a two or three inch layer of mulch. Sometimes you can find potted, blooming plants in the spring. If that's what you have, prepare the soil the same way, and plant them with the top of the rootball even with the soil surface.

Hyacinths are pretty easy to take care of. After they're done blooming this spring, cut off the flower stalk, but leave the foliage. It's important to leave the foliage because that's what is feeding the bulb and building it up for next year's flowering. You can fertilize lightly around the plant with a good bulb food at this time. Continue to water the plant until the leaves start to die down in May or June. Once the foliage has died down, cut it off and wait for the blooms next spring! Hope this helps.

Back to the top.

 

Question: I've tried to get my amaryllis to bloom a second year and haven't yet succeeded. What should I be doing?

Answer: Amaryllis are tricky, and most people find that while they may get beautiful greenery the second year, it's difficult to get the plant to bloom. You're not alone, and that's why so many people treat amaryllis as annuals, buying a new one each year. On the other hand, I've had people tell me that they've had blooms year after year. Folks have told me about all kinds of "tricks" they've tried, that have given them success, but personally, nothing's worked for me. I guess it keeps me humble!

Having said that, here's what you can do. When the amaryllis is completely finished blooming (often into February sometime), cut the flower stalk off but leave the green foliage. Place it in a bright, sunny window, give it regular water (making sure it doesn't sit in any water which would cause it to rot), and lightly fertilize it. In the spring, put it outside in a shady spot, water it, and fertilize it regularly with a good houseplant fertilizer (Miracle Gro works well). Around July, stop watering the plant, allow it to dry up, and cut off all the remaining leaves. At this point you can do one of two things: either leave the bulb as it is, or remove it from the soil, clean and dry it off, and store it in a paper bag. Either way, keep it in a cool dry spot through the summer. Around October first, repot it in fresh, good-quality potting soil, water it well, and place it in a warm spot to encourage sprouting. Once it sprouts be sure it gets good, bright light. IF it decides to bloom, you should see lovely blossoms in 3-5 weeks. I hope this works for you.

Back to the top.

 

Question: When can I cut the stems of my tulips once they have finished blooming? Also, how far down should I cut them?

Answer: That's a good question that many people have difficulties with! Here's what I tell people about what to do with their spring flowering bulbs like Tulips and Daffodils. First, once they're done flowering, cut off just the flower stalk, leaving the foliage alone. It's important that the foliage remains as that is what's building up the bulb for next spring's bloom. Cutting the flower stalk off makes the plant look better and prevents the plant from setting seed. (Allowing it to set seed will actually rob the plant of energy that could be better used in building up the bulb even more for next year.) After the flower stalk is cut off, it's a good idea to fertilize your bulbs to encourage good growth.

A month or two after the flowers are cut off; the foliage will naturally start to yellow and die down. Once the foliage has yellowed, it can be cut off down at ground level. It's done its job and you no longer need it. Cutting it off keeps your bed looking neat and tidy.

Back to the top.

 

Question: Should I water my bulbs through the winter?

Answer: After you're finished planting, be sure to water them in well. I like to put a 3" deep layer of mulch on top of the ground to help keep the soil from drying out too quickly. You'll need to keep an eye on the weather to see if you'll need to water any more. I would guess that you'll need to water two or three more times before things freeze up for the winter. Most winters you won't have to water again unless the winter is unusually warm and dry. If that's the case, just drag a hose over and give them a good soaking on a warm afternoon. Hope this all helps..

Back to the top.

 

Question: When should I dig my dahlia bulbs and how can they be safely stored throughout the winter?

Answer: Some people are turned off by the work required to winter over Dahlias, but believe me, it’s worth it for the glorious beauty these flowers give us in the late summer and fall. There are a lot of methods out there for how to winter Dahlias over, but here’s the one I like:

First, remember that the longer your Dahlias are in the ground curing, the more fully developed the tubers will be and the better the likelihood of bringing them through the winter successfully. We will usually have a light frost (hey, we've already had that!) this time of the year that starts to kill down the top of the plant followed by a hard freeze a few weeks later. Dahlias continue to grow and the roots continue to mature after light frosts, so leaving them as long as possible helps. You also want to cut the stems back a few days before digging. Leave enough stem (at least a few inches) to facilitate handling the clumps easily. Just be sure to dig them up before the ground starts to freeze, even a little. When you dig up the clumps, dig and handle them with care. Your Dahlias are fragile, especially right after digging. To remove the clumps, dig around on all four sides of the plant, about a foot away from the main stalk. Once you've loosened the plant from the fine feeder roots, push the shovel or spading fork under the clump and lift it carefully. Gently remove any large clumps of dirt and turn the clump upside down to let the plant cure a bit. After a couple of hours, you can remove the dirt with less risk of breaking those fragile tubers. When ready to clean the clump, use a garden hose to wash away as much soil as possible (the soil can contain microorganisms that can cause your tubers to rot over the winter). 

At this time, you can cut the clump into smaller pieces to make more plants for next spring. When dividing clumps, each division must have a piece of the crown with an eye and a big fat root (or part of one). Always sterilize your cutting tools after each cut, and while cutting the clumps, carefully inspect the divisions to make sure that there is no rot present. Remove all feeder roots and any stalk (both promote rot). After dividing your plants, wash the tubers again to remove any dirt missed from your first washing.

After rewashing, cut the end of the tuber. Any brown or rusty colored areas in the middle of the tuber indicate rot. If you see this, cut away toward the crown to see whether the tuber has a clear section that includes the crown. If so, the tuber should be viable. If not, throw it away. After cutting the divisions, treat the cut ends with a fungicide, such as Captan or sulfur to prevent rot from occurring over the winter. You should then label each division with the variety name. After cutting, dusting, and marking the tubers, let them dry for 24 to 36 hours. Drying time varies depending on temperature, humidity, and the size of the root. Be sure to only do this in an area that won't freeze.

There are numerous methods to store tubers over the winter. I don't think the particular method matters as long as you keep the tubers cool (above freezing but ideally below 50 degrees) and provide for an exchange of moisture between the tubers and the storage medium. Most people use vermiculite in plastic bags to store their tubers.  The way you do this is to add some vermiculite to the bag, put in some tubers and then add a layer of vermiculite. You can then add another layer of tubers and then more vermiculite. Some people use a separate bag for each clump to be sure that if one clump rots, it won't spread to the others. Make sure that each bag contains at least as much vermiculite (in volume) as tubers. 

Some people say that the plastic bags must be air tight while others only twist them so a little air can escape. In our area with our low humidity, I think you want the plastic bags to be more on the tight end rather than open. They don't necessarily need to be sealed shut, just loosely twisted or folded over is enough. After filling the bags, keep them in the coldest part of the basement or garage or another cool area that will stay around 40 to 45 degrees. It's important to store the tubers at a nearly constant, cool temperature. Freezing temperatures ruin tubers, and higher temperatures encourage microorganisms and fungus to destroy them as well as develop sprouts and feeder roots too soon. 

You'll want to check on the tubers once a month during the winter. Throw away any tubers that show signs of rotting. By checking frequently, you can get rid of any rotting tubers before the rot spreads to otherwise healthy tubers. If you make sure that the tubers of your Dahlias aren't touching when you pack them in the plastic bags, it will help keep any rot from spreading. 

In early spring, move your Dahlia roots to a warm location (dark, but room temperature) to encourage eyes to develop. Be sure to check the moisture in the bag and protect the tubers from drying out. You can add a teaspoon of water per quart of bag space 15 days before removing the tubers. Hope this all helps.

Back to the top.

 

Bookcliff Gardens
(970) 242-7766
755 26 Road (North 1st at I-70) • Grand Junction, Colorado 81506
Ask the Expert
©2008, Bookcliff Gardens