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Elisabeth C. Miller Library

Keyword: Winter gardening

Garden Tip #431

Believe or not, but when the first cherry tomatoes ripen in July it’s time to start planning the fall and winter vegetable garden in the Pacific Northwest. Beets, beans, kale and other cold hardy crops need to be sown in July or August so that they have a few weeks to bulk up before night time temperatures drop after the autumn equinox. The idea is to get the plants to almost harvestable size before the weather really turns cold, and then gardens acts as a kind of refrigerator, keeping the vegetables in stasis until we’re ready to eat them. If you miss the seed starting window there is still time to buy transplants from local nurseries until early September.

These two publications from Washington and Oregon State University Extensions have all the details to ensure success.

Pruning Hellebores

I am noticing that the flower bud shoots for my hellebores (Helleborus x hybridus), are starting to push up above the soil surface. There is still a substantial stand of foliage in good condition.

My question is about pruning. I know I’ll need to prune about half the leaves away (I understand that the cut should be made at the base) to give the flowers more visibility. Does it harm the plant to prune it during this cold snap? Does it harm the plant to cut ALL the old leaves off in December as the bud stalks begin to appear?

I would appreciate any guidance you can give me, such as when and how extensively to prune them.

 

According to Hellebores: a Comprehensive Guide by C. Colston Burrell and Judith Knott Tyler, “all the hybrids maintain their foliage (…) throughout all or part of the winter (…) In any case, as the flower buds begin to stir in the center of the rosettes, it’s best to remove all the foliage to make way for the flowers. Nothing spoils the garden display like a tangle of flowers wrestling with winter-burned leaves. The juice is caustic and sometimes causes a rash, so take care when removing the old leaves.”

In The Gardener’s Guide to Growing Hellebores, Graham Rice and Elizabeth Strangman advise a more time-intensive method:
“The best approach is to cut off some leaves during the autumn and early winter when the garden is put to bed, concentrating on removing dead leaves and any showing signs of blackening (…) By Christmas time they should be thinned out sufficiently to leave a good circle. However, as our winters become windier it may be wise to remove them entirely at this stage. (…)Thin the leaves further as the flower stems emerge, then just before they are in full flower remove all the old leaves. (…) To compensate for the removal of the last of the leaves the plants deserve a good mulch.” They go on to suggest compost or a mulch of leaves for this purpose. The cold snap is unlikely to harm even recently pruned hellebores, as they seem to thrive in the cold.

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Winter watering

Can you tell me, what’s the deal with watering in winter? I’ve heard that foundation plants which don’t catch the rain under the eaves must be watered even in wintertime. Someone else says that watering anything in winter subjects it to freezing.

Now I’m in a quandary. I don’t want my plants to freeze to death, nor do I want them to die of dehydration. So what’s the answer?

 

According to Colorado State University Extension, you do need to water if there has not been snow or rain. You should water when the temperature is above freezing and the soil is not frozen. You should water early in the day so that the water can soak in before it gets cold overnight and freezes.

Here in the Puget Sound area we do not have freezing temperatures very often so you should go ahead and water, especially those plants under the eaves.

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sowing herb seeds in July and August

Are late July and early August still a good time to start sowing seeds for basil, parsley, and coriander in Seattle?

According to Winter Gardening in the Maritime Northwest by Binda Colebrook (Sasquatch Books, 1998), you can sow coriander in late August to early September and as long as the winter is not too harsh, you should have success. You may want to keep the plants under cover during winter.

When you sow parsley, Colebrook recommends looking for European varieties which are cold-hardier than the American type. The following article, from the British paper The Guardian (July 1, 2006 issue) discusses summer sowing:
Summer-sown parsley by Sue Stickland

Here is an excerpt:

“Spring-sown parsley often struggles, but sow now and it’s easier to get healthy plants. These should give a good crop right through to autumn, and look as decorative in beds, pots and troughs as they do on the plate.

Sow directly where it is to grow, or into small pots for transplanting, and keep it moist. In steady July temperatures, germination should take a couple of weeks (quicker by half than in spring). Plant out seedlings from pots as soon as they are big enough, and before the ‘tap’ root hits the bottom. This will give stronger, more resilient plants.

The main enemies of spring-sown parsley are aphids and carrot flies. Aphids not only make the leaves unappetising, but carry viral diseases; carrot flies tunnel into the roots, weakening the plant, just as they do with their main vegetable host. When parsley starts to yellow and redden, and plants become stunted, one or other of these pests is usually to blame. July sowings avoid the worst attacks, provided you keep them well away from any ailing plants. Never try to grow this herb in the same spot twice.

For vibrant, deep green leaves, the plant must also have rich soil and plenty of moisture. Add well-rotted manure or garden compost (or a bagged equivalent) to a garden patch, and to the potting compost in deep troughs and pots. Don’t forget them in dry spells – most herbs won’t need watering, but parsley will. When it turns cold, bring pots into a cold frame, greenhouse or other warm, protected spot. These late-sown plants will provide welcome fresh sprigs in winter and early spring.”

Basil is a half-hardy annual, and is best sown into pots in early spring, or directly into the garden in late May. I don’t think you can successfully grow an outdoor fall/winter crop. Mary Preus, author of The Northwest Herb Lover’s Handbook (Sasquatch Books, 2000), suggests potting up plants from your garden in September and moving them indoors. If given the right light and care, you can keep harvesting throughout the winter.

Nagami kumquat hardiness

I live in Redmond, WA and I recently noticed that we have been classified as Zone 8A – 8B instead of 7B. Most sources I read state that year-round outdoor planting for Nagami kumquats is recommended only for Zone 8 and above. What is your take on this? I’ve had a Nagami since November, but it has acted differently from what sources I read indicated. I also have a Meyer Lemon that I bring indoors and it did fine over the winter, but the Nagami shed all its leaves within 2 months starting from January. The peculiar thing was that the leaves shed were all green and healthy, leading me to believe it had entered dormancy. It started to grow new leaves in April, but I’m still puzzled why it entered dormancy in indoor conditions even though the less cold-tolerant Meyer flourished.

Long story short, if the Nagami sheds its leaves every winter, will it ever have enough time to produce mature fruit even if it did survive outside?

If you have any particular kumquat or citrus experts you could recommend, that’d be great! Thanks!

According to a local nursery (Raintree), the Nagami kumquat is hardy to 18 degrees, and may produce fruit here. So if we have a cold snap, as we occasionally do, it may be hard on the tree if it’s growing outdoors–unless you can provide it with protection. A friend of mine has grown kumquats before, and they produced fruit, but I believe a long period of subfreezing temperature killed her tree one winter/early spring.

Growing Citrus by Martin Page (Timber Press, 2008) says that kumquats (Fortunella japonica or synonymously Citrus japonica) are prone to zinc deficiency which results in smaller leaves and shorter shoots. They are considered very hardy, but this may be “due to their long winter dormancy.” Nagami grown in a pot will reach about 4 feet, but outside, it can get to 13 feet tall. Fruit is harvested October to January.

It’s possible your Nagami kumquat dropped its leaves because it was entering dormancy, but there are other causes to consider as well. According to the source cited above, leaf drop in citrus trees can be caused by:

  • sudden environmental changes (temperature, humidity, etc.)–bringing a plant inside to overwinter is likely to expose it to dry air
  • underwatering (don’t overcompensate by watering a leafless plant because it has no way of transpiring the water without its leaves; prune it the next spring by reducing shoots by about a third of their length)
  • overwatering (make sure container drains well; soil that doesn’t drain well can lead to yellowing leaves and leaf drop)

You may want to speak to a local expert at the Western Cascade Fruit Society, or the Home Orchard Society.

Also the nurseries that specialize in fruit trees are good resources:
Raintree

Cloud Mountain Farm

Burnt Ridge

Rhododendrons with winter flowers

Aside from ‘Christmas Cheer,’ are there types of Rhododendrons that have winter flowers and flourish here? I am imagining planting a couple in an island beneath some hybrid elm trees, so they would be in part shade. I have plenty of irrigation, and there is a slight slope to the location.

Another variety which is early to bloom is ‘Nobleanum.’ American Rhododendron Society’s blog has a post by a Pacific Northwest author who lists several others:

  • ‘Bo Peep’
  • ‘Seta’
  • ‘Snow Lady’
  • ‘Cilpinense’
  • R. mucronulatum ‘Cornell Pink’
  • R. dauricum
  • R. moupinense
  • R. strigillosum

One can also search the American Rhododendron Society site for varieties of Rhododendron which meet various criteria, including bloom time.

Meerkerk Gardens on Whidbey Island lists rhododendrons by month of bloom.

The Rhododendron Species Botanical Garden might be another good resource. They mention that they have just a few species which flower early.

on planting oriental lily bulbs

I was recently given 6 Oriental lily (Lilium) bulbs – bare root. It seems much too cold (late February) to put these in the ground. They are currently naked in the garage, but would it be better to pot them until the ground is workable? I have not raised lilies before, other than daylilies.

Generally, it is good to plant bulbs soon after you get them, but if you need to wait (due to cold weather and unworkable soil), keep the bulbs somewhere cool, and keep them “in moist sand or peat moss until scales plump up and new roots begin to sprout” (Sunset Western Garden Book, edited by Kathleen Norris Brenzel, 2001).

The Gardener’s Guide to Growing Lilies by Michael Jefferson-Brown and Harris Howland (Timber Press, 1995) confirms your thought that it is too cold to plant them out in the garden (I would wait until the threat of freezing temperatures subsides). According to the resource mentioned above, your lilies will do very well in pots, so what you could do is pot them now, and if you decide you would like to move them into the garden when it warms up, you could either put them, pot and all, into the border, or gently remove them from the pot without too much root disturbance, and plant them in the soil.

Garden Tip #107

While vegetable gardeners are inundated with zucchinis and other summer produce it can be hard to imagine the winter garden. But July is the time to plant seeds for fall and winter crops of cabbage, Asian greens, collard greens, spinach and lettuce. Transplants should go in the ground in mid August. Perennial and biennial flowers can also be started from seed right now. For an excellent list of what plants to sow throughout the year check out The Maritime Northwest Garden Guide produced by Seattle Tilth. It is available for $22.00, including tax and shipping. Call 633-0451 or order a copy online.