growing artichokes

I have about 20 healthy artichokes. They did not die back in the winter. I think that there is a lot of bug activity going on in them: earwigs, slugs. Should I cut the plants to the ground and dispose of the possible bugs that have wintered over in them? I hate to do it because the foliage is so lovely.

I have grown artichokes for the last 5 years, so I am going to answer from personal experience.

Do not cut the plants back because they will be sending up their flowers in the next few weeks (depending on the weather, it could be as late as June). Cutting it back now will just delay any flowers for at least 6-8 months, if not kill them outright. While I too have had numerous slugs, earwigs and cutworms, I find that their damage is minimal, and does not hurt the flower show. And for eating I just wash them carefully and then turn a blind eye when I find a few earwigs in the pot after cooking!

Sprinkling some Sluggo (or comparable less toxic slug bait) into the leaf joints will help too.

Hydrangea care

I have a few Hydrangeas that have not been doing their best. I think I have the exposure down, and their colors. I need advice on what fertilizer is best for them and when, how much and how often to apply it. I try to stay as organic as possible.

According to Hydrangeas: A Gardeners’ Guide by Toni Lawson-Hall and Brian Rothera (Timber Press, 1995), hydrangeas do not generally require special feeding. If you wish, you can apply a general fertilizer twice a year. “As important as feeding, and in fact another method of supplying nutrients, is mulching.” The authors suggest using mature compost or leaf-mould. Mulching in the spring to a depth of about 3 inches will help protect the roots of your hydrangeas from drying out (but never put mulch directly up against the base of your shrubs). Mulching also suppresses weeds. Since you garden organically, mulch may be your best bet for supplying a slow and gentle dose of nutrients. If the plants continue to fare poorly, you may want to do a soil test to see if there is some kind of nutrient imbalance that needs correcting.

Chrysanthemum and sporting

I was puttering around in my flower garden and discovered a chrysanthemum that has apparently sported. The same plant has one substantial stem with distinctly different colored flowers. I have never read of this happening before. It is doubtful it is anything but a different color but hey it happened in my garden.

“In common with many other plants the Chrysanthemum occasionally produces a mutation or change called a “sport.” This is a variation from the normal for a particular variety. The cells of the part or parts affected change and cause the difference. While this can occur in any part of the plant or bloom, the most noticeable is a change of flower colour. You may for example find that a white-flowered variety has changed to yellow and this can be of any degree from a stripe in one petal to a whole flower, or even the whole plant being affected. Cuttings taken from a whole plant sport are likely to stay the new colour. Where a whole bloom sport occurs they would probably need to be taken from the stem concerned. If only a petal or two, the chances of fixing it are rather slim.”

Source: A Plantsman’s Guide to Chrysanthemums, by J. Woolman, 1989, p. 115).

So it is fairly normal, but interesting anyway!

disease-free flowering crabapples

I am looking for a Malus (crabapple), not necessarily native, but is decorative in terms of blooms and foliage. I am also interested in plant diseases. I am hoping for a tree that will mature to about 20 feet with a 20 foot spread. Growing conditions are half shade, half sun, behind a semi-dense fence. We live in the San Juan Islands where the soil is not great and the tree will not get much water past establishment.

Here is what I found about the culture of flowering crabapples from the book Flowering Crabapples, the Genus Malus, by Fr. John L. Fiala (1994), p. 45:

“Crabapple trees luxuriate in full sunlight in deep rich soils that are well drained. Soils with a pH range of 5.0 to 7.5 suit crabapples well, but the ideal pH range is from 5.5 to 6.5. Even if gardeners are fortunate to have ideal soil conditions, they may not be able to allocate the best part of the garden to crabapples. Flowering crabapples, however, are not greedy and will accept almost any soil that is not waterlogged or overly dry. As long as the soil has a reasonable amount of nutrients and water, crabapples manage to do very well.

“Like most plants, crabapples prefer rich sandy loams, but even in heavier clay soils they do better than many other trees and shrubs and seem to bloom well once they are established. They will accept slightly wetter soils than lilacs, for example, but in these heavier soils they should have excellent drainage as they will not grow in waterlogged, swampy areas nor in soils inundated for long periods of time.”

Regarding particular trees you might like that would be disease-free, I found a couple of crabapples that were listed in The Pacific Northwest Gardener’s Book of Lists,by Ray and Jan McNeilan (1997). This is from page 24:

1. Malus ‘Prairiefire’ has red foliage when young that matures to deep green, has bright pink/red blossoms and deep purple-red fruit. It grows to 20 ft x 20 ft and has excellent resistance to scab and mildew (Pacific NW scourges).

2. From the book Flowering Crabapples, the Genus Malus, by Fr. John L. Fiala (1994), p. 147:
Malus sieboldii ‘Calocarpa’ (trade name, Redbud crabapple) is a dense, upright to spreading tree, 15 ft high and as wide… buds deep red, opening to single, white to pink-white flowers 1.4 in across; fruit 0.4 in diameter, bright red to red-orange… A reliable, abundant, annual bloomer… One of the most beautiful of all the ornamental crabapples both in bloom and in fruit. Birds relish the small fruit which never is messy.

From The Pacific Northwest Gardener’s Book of Lists, p. 25, I found that this tree is rated ‘excellent’ in terms of resistance to both mildew and scab.

3. Malus ‘Strawberry Parfait’ is a “vase-shaped, spreading tree 18 ft high and 20 ft wide; leaves red-purple, turning green with maturity; buds red, opening to single, pink flowers in clusters; fruit yellow with red blush, 0.4 inch in diameter. Excellent disease rating but not rated for fire blight [bacterial disease]. Not very ornamental.”
From The Pacific Northwest Gardener’s Book of Lists, p. 25, I found that this tree is rated ‘excellent’ in terms of resistance to both mildew and scab.

[Note: fire blight appears to be more the issue in the midwest and eastern U.S.]

Clematis and hard pruning

We are tearing out an old wood fence and replacing it with a new cedar fence, 6 feet high. We have a mature Clematis montana rubens growing on the old fence, prolific in growth and bloom, that I would very much like to save. Can I save it? We will have to start taking the old fence down right away. The new one is being installed next week, so I cannot wait until fall, which would probably be a better time to cut it back. Where do I begin pruning? Where do I stop? Anything I can do to lessen the shock to the plant?

Clematis montana is in pruning group 1 (or A) which means they do not take well to hard pruning. However, if it is the only way to save your Clematis, it is worth a try.

This is what the British Clematis Society recommends:

Category 1 (or A): No pruning.

“This category includes: C. montana If you wish to prune these types because they have outgrown their space they should be pruned immediately after flowering. You may or may not lose your plant as a result of the pruning. You might want to reduce the plant size over two or three seasons rather than in one go.

How-to: Start at the bottom of the plant and work your way up the stem to the first pair of plump, healthy buds. Prune the stem above the buds and remove everything above the cut. Treat each stem in a similar way.”

Pruning is safer than transplanting:

“If a Clematis is to be replanted from an existing site, the late winter before bud break is the time to do this. However, it is only the large-flowered cultivars that generally can be replanted from an open ground position due to their large fleshy roots. The Clematis species and their cultivated forms have a very fibrous root system that usually breaks up when it is being dug up. The montana types are extremely difficult to replant once they have been established for more than two or three years.”
Source: The Gardener’s Guide to Growing Clematis, by R. Evison, 1998, p. 39).

growing corn lilies

I am very interested in corn lilies growing in the Seattle area, and I would like to know how to grow them and where to find some.

In the fall, corn lilies (Ixia) have already done their flowering, and I do not know of any place to send you to see them. They aren’t common, but some avid local gardeners do grow them.

Regarding how to grow these bulbs, the following is quoted from Sunset Garden Book (2001), pp. 406-407:

African Corn Lily:

Clump of narrow, almost grasslike leaves sends up wiry, 18-20 inch stems topped by short spikes of 2 inch flowers in late spring. Each six-petaled blossom opens out nearly flat in full sun but remains cup-shaped or closed on overcast days. Colors include cream, yellow, red, orange, and pink, typically with dark centers. Most Ixias sold are hybrids of the South African species Ixia maculata.

Grow in well-drained soil. Where winter lows usually stay above 20 degrees F, plant corms in early fall, setting them 2 inches deep and about 3 inches apart. … Let soil go dry when foliage yellows after bloom. Where corms will not be subject to rainfall or irrigation during dormant period, they can be left undisturbed until the planting becomes crowded or flowering declines. When this occurs, dig corms in summer and store as for gladiolus until recommended planting time in your area (the nursery can tell you this). Where corms will receive summer moisture, dig and store them after foliage dies back; or treat as annuals. Potted corms (planted close together and about 1 inch deep) can be stored in pots of dry soil.

Be careful not to pull them up accidentally, as the new growth in spring looks a lot like grass!

propagating Stipa

Can ‘Giant Feather Grass’ (Stipa gigantea) be propagated by division or by seed only? What are the requirements for successful propagation?

You can propagate Stipa either by division or by seed. According to the A-Z Encyclopedia of Plants and the AHS Plant Propagation books, both ways need to be done in the spring. Specifically, seeds should be sown in containers in a cold frame in spring. Divisions should be done from mid-spring to early summer.

Seeds should be sown when you can maintain a temperature of 59 degrees F. Most grass seed germinates in a week. Transplant seedlings one to a pot or cell as soon as they are large enough to handle. Transfer pots of established seedlings to a frost-free place to grow. Plant out in mid-spring.

Divisions – cut back the foliage for easier handling, then lift the clump. Shake loose soil from the roots or wash clean, to make it easier to separate them. Use a sharp knife to divide the clump into good-sized sections. Trim any overlong or damaged roots. The divisions can then be replanted in the garden.

I have also noticed that in my garden, Stipa usually reseeds itself and if you look carefully you may find some small seedlings already started, which you can transplant.

helping tomatoes to ripen

I purchased an heirloom tomato at Home Depot (I know) and planted it deep in a pot in about the middle of June. I put the pot in a very sunny spot, I have fed it twice and watered it daily. It grew like crazy, then slowed when it began to show fruit. Now it is full of fruit but nothing wants to ripen. I removed a tomato today that had split.

Is there anything I can do to help the tomatoes ripen?

A few suggestions:

–Do not fertilize the plants any more, as this mostly stimulates growth rather than fruit ripening.

–You can drape clear plastic over the plant to keep the temperature up, especially at night, just make sure to remove it during the hottest days so you do not cook the plants.

–Stressing the plant by cutting the roots with a spade 8-12 inches from the stem will encourage ripening. Underwatering will also stress the plant.

–Remove any flowers and really small fruit that probably will not ripen anyway to encourage the plant’s energy towards the developed fruit.

–If you still end up with green tomatoes, bring them inside before the first frost, they may ripen on the windowsill.

Also available in many bookstores or libraries (including the Miller Library) is Growing Vegetables West of the Cascades, by Steve Solomon.

transplanting Schizachyrium scoparium

Schizachyrium scoparium (Little Bluestem) seems to me to be difficult to transplant. They die on me when moved. What could I be doing wrong? The time of year? Adequately watered?

According to the Color Encyclopedia of Ornamental Grasses, Schizachyrium scoparium requires full sun, prefers good drainage or sloping ground, does not persist on highly fertile soils or in excessively moist conditions, and suffers if the crowns are crowded by mulch.

Propagate by seed or by division in spring.

Grasses are sensitive to soil level, especially when young. Ideally, the crown of the grass should sit just slightly above the soil surface. Planting too low can rot grasses and planting too high can cause them to dry out and die.

Mulch of all sorts can be an efficient method of controlling weeds and conserving soil moisture. Many species, such as Schizachyrium scoparium, cannot tolerate having mulch pushed up around their crowns, a practice that often promotes rot and disease at the base of the plant.

Source: Color Encyclopedia of Ornamental Grasses, by R. Darke, 1999, pp. 121, 276.

on slowing down Agapanthus bloom

The Agapanthus in my greenhouse are budding. I would rather not have them bloom now. Can I set them outside to slow them down or would that do more harm than good?

If your Agapanthus has set buds and is beginning to flower, there is not much you can do to slow it down. Putting it outside will not harm it when the danger of frost is past.