late starting seedlings

Uli via pbs
Mon, 07 Mar 2022 16:37:51 PST
Hello Mark,

Your question about how to handle late starting seedlings has been asked 
quite often.

There are several things to keep in mind. Warm growing conditions induce 
dormancy in winter growing bulbs. Dry growing conditions do the same. 
The combination of both may be fatal to young seedlings as their small 
bulbs may not be big enough to survive the first dormancy especially if 
it was induced prematurely by these factors.

How to overcome this?

Depending were you live, it is important to keep the growing temperature 
frost free but as cool as possible for as long as possible into spring. 
If you germinate your seed in a greenhouse it is a good idea to move the 
seedling pots from the greenhouse to a half shaded sheltered spot in the 
garden. Always give artificial shade for a few days after the move. 
Greenhouses tend to warm up considerably from March onwards (northern 
hemisphere). If this is not possible because of frosty nights it is 
important to ventilate the greenhouse as efficiently as possible and to 
wet the floor during sunny days in order to increase humidity. Seedling 
pots must NEVER dry out. Once growth would be stopped by a dry interval 
it will not resume and the resulting bulbs will remain small and weak.

Even outside in the garden it may be useful to apply artificial shading 
by using horticultural fleece or shade cloth to cover the seedlings. I 
put a wire mesh caging over them to stop birds and other creatures 
digging in the pots. The cage will prevent the shade cloth lying 
directly on the plants. it all depends on the climate you live in. A 
place where the sun is welcome in winter may become to warm in spring so 
it may be necessary to move the pots into a shaded or half shaded place. 
Shade of buildings with otherwise bright light is a good option.

Fertilizing must not be neglected: It is better to fertilize more often 
but with lower concentration. Especially at the end of the growing 
season I have found fertilizer very beneficial.

For valuable small seedlings the effort of moving the pots into more 
favourable growing conditions and applying artificial shade pays off, 
this way most bulbs can be kept green well into May, some even longer. 
Follow what the plants tell you: as long as at least some leaves are 
still green, keep watering but once all foliage has died down naturally 
stop watering. Otherwise rot may set in. Young seedling bulbs should be 
left in their pots in the substrate during dormancy. These pots should 
not bake in the sun but kept in a shady cooler place in summer.  A 
gentle hand watering with a fine rose every 4 weeks or so will prevent 
them from becoming too dry. Observe the pots for signs of new growth in 
autumn. Again, this depends on where you live. Warm weather delays 
sprouting and moist cool weather triggers it.

Last but not least my recommendation for sowing winter growing bulbs is: 
not to sow after the end of December. The best results are obtained by 
sowing in October. The seed of most bulbous plants can be stored in the 
fridge until optimum sowing time.

Bye for now


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