When to start watering--Second time around

Jane McGary janemcgary@earthlink.net
Fri, 03 Oct 2003 11:47:36 PDT
I live in an area (the maritime Pacific Northwest USA) that typically has 
no rainfall in July and August; this year there were only two rainy days in 
September as well. However, October through May and often into June is 
almost continually wet.

Most of my more interesting bulbs are grown in permanently covered cold 
frames, in pots plunged nearly to the rim in sand. One frame has removable 
covers that I put on only from about mid-November to mid-March; it holds 
bulbs well adapted to the climate here, things I can grow in the open 
garden but need to have a stock of for safekeeping.

I hand-water the covered frames on different schedules. Frame 1 is not 
irrigated from about the end of April through late September, and often I 
don't have to water it much during winter because the sand draws up ground 
water, which penetrates the mesh and clay pots. I have a dry section 
in  Frame 4 that is managed the same way. Frames 2 and much of 4 are 
watered more, including enough water in summer to keep the soil just 
slightly moist. In Frame 5 I have a lot of seedlings, which I water some in 
summer even if they are xeric species, in order to keep them from 
desiccating while too small to recover from it. With them I have various 
bulbs that tolerate summer moisture, and also one section for 
summer-growers such as alpine Rhodophialas and lilies, which I don't water 
in winter though they don't dry out, either.

I should point out that being plunged, the pots do not get hot and 
desiccated as they would if kept above ground. Also, summer nights are 
quite cool here, so the soil doesn't heat up a lot even in the frames. When 
I lift the pots around the end of July, the bottoms are cool to the touch.

In order to decide where to put a given species, I read about its native 
habitat. Sometimes I interpret this information wrongly and find out later 
that I've misplaced it. If something doesn't thrive in one area, I move it 
to another. The most useful books for this purpose are Martyn Rix's "Random 
House [UK Pan] Book of Bulbs" and Brian Mathew's "Complete Guide to Growing 
Bulbs," supplemented by field guides such as those by Oleg Polunin, and of 
course the notes of the seed collectors who enabled me to grow the bulbs. 
Even better is visiting the source area!

This is a lot of hand-watering, considering that the five frames are 40 to 
44 feet long and 4 to 5.5 feet wide. However, I like taking the time to 
observe the plants.

This year I watered a bit too early, with the first rain, because soon 
afterward we had a historic record heat wave in late September. I kept the 
pots moist, however, because I thought it would cool them down, and so far 
things look all right.

It's true that you can retard growth by delaying watering, but I feel that 
this can slowly sap the strength of the plants over several years. And it 
can be death to tiny bulbs. I'd rather protect them from the infrequent 
severe cold here, and have them flowering throughout fall, winter, and 
early spring. However, this might not work for those in colder areas such 
as the Northeast and Midwest USA, or Canada.

Someone mentioned avoiding getting water on the foliage of certain bulbous 
plants from very dry areas. In the new issue of the AGS journal, Rannveig 
Wallis mentions problems with Botrytis on foliage in their bulb collection 
in soggy Wales. I don't have any trouble with this disease for some reason, 
even with the wet winters, though I do try to water below the foliage where 
it's feasible. The only Botrytis I have seen here has been on the very 
leafy Fritillaria davisii, and on some Fritillarias I got from China via 
Paul Christian (most of them died despite lots of spraying). However, 
Botrytis paeoniae, which seems to have come here on some plants I purchased 
from a Midwest grower, has destroyed many hybrid peonies in the garden, and 
I no longer plant them.

In summary, I think most bulbs should not become bone-dry even while 
dormant, but keeping them just faintly moist is tricky unless you plunge 
the pots. (Using peat-based composts causes problems, too; I use forest 
loam as the organic component instead.)

Jane McGary
Northwestern Oregon

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