When to start watering; emerging leaves without rain; California N-S gradient

Gastil Gastil-Buhl gastil.buhl@gmail.com
Mon, 28 Oct 2013 18:20:45 PDT
Several PBS members from northern to southern coastal California and even the south of France have described when bulbs emerge in the fall relative to when the rain or irrigation begins. My garden is 300 miles south of Mike's and 100 miles north of Lee's but unlike the others, no significant rain has fallen yet this fall. (Rainfall amounts, in inches: June 0.10, July 0.06, August 0.00, September 0.02, October thru 27th 0.00; 0.01 inch is roughly 0.03 cm.) Normally I would have began irrigating in September but this year all is delayed by a bulb garden renovation project which is taking much longer than imagined. To find a "silver lining" in this situation, I will share my notes on which bulbs emerge without a moisture trigger. 

In September whilst digging up bulbs I noticed most were dormant, few had shoot tips emerging from the bulbs (none thru soil surface) and none had roots emerging. Then later in October more and more had shoots (just the white cataphyll) and now even some have roots. This is without significant precipitation. Contrast this with the N. tazetta growing in a different bulb bed that has been watered regularly since early August where now the leaves are 6 inches/15 cm high and Ipheion leaves nearly as long. Lately night temperatures have dipped below 50F / 10C and day temperatures are mostly in the 70's reaching 80F/27C less often. Now the soil is around 60F/15C at 4 to 6 inches depth. This hints Narcissus tazetta primarily responds to soil moisture but responds to cooling temperatures even without any moisture, other than air humidity or dew. Another generalization I feel confident making is that with moisture the roots emerge around the same time as the shoots but in absence of m
 oisture the shoot precedes the roots. The exception to that is Scilla hyacinthoides which I found was actively growing roots before any sign of shoots, 6 inches deep in air-dry soil. This coastal air is a lot less dry than Arizona and likely less dry than Pasadena but more dry than San Jose or the north coast.

Order of emergence with lack of precipitation:
	1. August: Scilla peruviana, Oxalis livida, Chasmanthe
	2. September: Watsonia, Oxalis tenuifolia
	3. Early October: Babiana, one species Gladiolus (unidentified), Tropaeolum hookerianum*
	4. Mid-late October: Scilla hyacinthoides
	5. Narcissus tazetta, few Muscari, few Ipheion, about a third of the Freesia (commercial hybrid)
	6. Amaryllis belladonna white
	7. Veltheimia bracteata
	8. Amaryllis belladonna pink... but ONLY where watered nearby

No sign of emergence yet with no precipitation:
	1. dutch iris
	2. bluebells, which I expect to emerge around December or January
	3. Camassia, which I do not expect to emerge until perhaps late January
	4. Most of the Muscari, most of the Ipheion, most of the Oxalis purpurea
	5. Sparaxis
	6. Moraea (that I have)
	7. Ixia
	8. native CA including Dichelostemma capitata and congestum, Triteleia laxa, Brodaiea elegans and Calochortus venustus
	9. Daffodil type Narcissus such as King Alfred. I expect those will emerge in December.
	10. Leucojum (aestivum I assume)

*cannot tell root from shoot; it emerged from the lower part of the tuber but was growing upwards like a shoot would.

All of these data are for in-ground plantings except Veltheimia and two of the three Babiana species and the early Oxalis in pots. Also in pots are blue Freesia laxa which I can now confidently report only start growing once watered. 

I expect those which began growth earlier will grow more strongly and those whose growth was delayed will suffer and take a year to regain vigor.  In the long term the renovation of the bulb beds will be worth the stress this fall. The new beds now have wire mesh lining and increased height. And some sections had become ridiculously over crowded, the bulbs growing tunic-to-tunic, misshapen by the crowding. Bearded iris had overran Narcissus, Ipheion and Muscari had spilled out into the walkway with seedlings, and the Sparaxis corms were so crowded they were shoving themselves out of the ground. The bearded Iris had slowly pushed the large rocks of the border out into the path or grew on top of the rocks. 

Several species which have not emerged in dry beds did emerge a month or more ago in irrigated beds, such as the Watsonia, Narcissus, Muscari, an "Autumn Crocus" and Ipheion. If not for the renovation digging, I would have begun irrigating the bulb beds in September. I began digging up the bulbs in August and just finished this past week. The living room floor is lined with paper bags full of bulbs needing to be back in the ground. It may take the next whole month to replant them all. I will take note and report of any which have sprouted while in their bags waiting, and will take that as an opportunity to learn more about the bulbs emergence habits than as self recrimination for delaying their winter growth.

- Gastil
Santa Barbara, CA
Please excuse slow response to email; if it is light out, Im out back digging!

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