Onion sets can be planted in a shallow furrow in the garden soil. This is above all good when you have a sandy soil. Reasons:
- Onion plants are better “fixed”in the soil. After planting, birds will not pull them out that easy.
- The soil in the furrow is lower, so less drying out.
- When watering in the furrow, the soil next to it stays dry. So less weed next to the row.
- The furrow indicates where the onions have been planted. No marks needed.
A)# Onion fly and carrot fly
I used to sow or plant rows of onions (O) next to rows of carrots (C) (or a few rows of beetroots). So OCOCOCO. This can reduce the attack of your plants by the onion fly or carrot fly. It does not always help that good. You better not plant the sets too early; see chapter B)# Planting time in this tip.
And (found out in 2015) a layer of hay or short grass around and between the onion plants helps well against diseases and insects. See further in this tip at E)# Test: planting date and hay around.
B)# Planting time
(The description below is valid when you don’t put hay or grass on the soil between the onion plants).
Plant a short row of onion sets in early spring. Do not plant too many onions. There is a big risk that they are attacked by the leaf miner fly (curled leaves) or onion fly (maggots in onions, plants die).
So you better plant many (all) onion sets in mid spring or later.
These onions have been planted in early spring (April). Many onion plants suffer from attack by onion flies or miner flies.
These onion sets have been planted at mid spring (May 15). All plants are healty. From 50 onion plants only 2 died due to attack by the onion fly. In late summer (August) the harvested onions have about the same size as onions from sets planted in early spring (April).
Below a description with photos.
- Let the onions grow bigger indoors.
- Let the onion plants grow bigger.
- Photos above of April 2, May 1 and June 1 (early, mid and late spring).
1. Under a tunnel
2. Hay around the plants
When you plant onion sets in the garden soil, you better put a layer of dry hay (or mowed grass) around and between the small onion plants. The plants grow well, the soil does not dry out so easy and the plants suffer less from insects. More info at chapter E)# test: planting date and hay around.
3. Weird shaped onions
Early planted onion sets can give strange (weird) shaped onions, see photo above. The onion sets of these onions were planted on March 16 (winter/spring). Dry hay was put on the soil between and around the small plants. The harvested onions are very big but they have strange outer layers. These onions can be used in the kitchen, but preparing the onions is some harder.
Onion sets planted in early May (mid spring) result in normal looking onions.
C)# Planting onions
C1) Testing if sets are good
- When needed, lay stepping boards on soft soil.
- Always stand on a lane or on stepping boards to overcome “hardening”of the soil.
- Fix an elastic string between 2 bamboo sticks. See tip 2) Simple….. nr 4.
- Or use a nylon cord with knots. See tip 2) Simple…… nr 64.
- Use a hoe to loose the soil and to make a furrow.
- Make a V -shaped furrow using a board. See tip 2) Simple…… nr 2. Or use a garden trowel. Depth of the furrow is about 5 centimeters ( 2 inch). Spread the ground that you “gather” elswhere over the garden.
- Plant the onion sets. Distance between onion sets about 10 cm (4 inch). Plant depth in the soil: half of the onion size or deeper.
- Remove the elastic string or cord with knots.
- Hoe the soil next to the furrow. Earth will fall into the furrow until top of onions is just visible (or just invisible).
- Remove the stepping boards. Hoe the soil where the boards have been laying on.
In tip 22 (Sowing onions) you can read that “mulching” reduces the attack by insects:
When onions are about 10 cm (4 inch) high, you can put organic material on the soil around and between the plants. This is called “mulching”. Put a thin layer of mowed grass or dry hay on the garden soil. There will be less weed plants between the onions and the soil does not dry out so fast. Less onion plants will die or will be attacked by insects. See photo below.
On the photo above there are 2 rows of sown onions next to each other. At the left side of the yellow line, dry grass has been put on the garden soil between the plants. Many sown onions grow there.
At the right side of the yellow line, no grass has been put there. Many sown onion plants died there. After removal of the dead onion plants, onion sets have been planted there.
So mulching next to and between onion plants reduces the attack by insects. This works well at sown onions and at onion sets (see further).
E)# Test: planting date (March 20 to May 1) and hay around.
To find out when onion flies or leaf miner flies lay their eggs on onion plants, the following experiments have been executed:
On these photos you see the row with onion plants (between yellow arrows) on May 1 (above) and June 1 (below). round and between the biggest onion plants there is dry hay.
E2) Big onion plants, first year:
On July 4, the onion plants are bigger. At some plants the leaves curl or lie down (flopping over). These onions are good for harvesting. A few days later all onion plants have been pulled out of the soil. Click on the photos for wide screen view
E5) Results and conclusions:
- Most onion sets grew into big onions; 38 onions out of 43 sets (first year) and 115 onions out of 129 sets (second year). This is about 89 % “yield”.
- Putting hay around the onion plants works well against attack by onion fly and leaf miner fly. Even during the “risk period” of the leaf miner fly (early spring, March and April).
- A number of onion plants showed curled leaves (maybe caused by the leaf miner fly), but the big onions looked normal.
- Maybe the “disappeared” onion plants have been eaten by the maggots of the onion fly.
F)# Onions planted early May (mid spring).
In early May, 4 rows of onion sets have been planted in the garden soil. Dry hay has been put between the onion plants in June. Just to find out if this results in good onions. The soil around the onion plants does not dry out so fast thanks to the layer of hay.
Pull the onion plants out of the garden soil. Let them dry on the garden soil or on grass (see photo above).
After drying, the leaves and stems have been cut off. Then the onions were laid in the boxes.
Four rows of 42 onion sets each (168 sets in total) resulted in: 160 onions, weighing 14.5 kilogram (without leaves). There were 125 big onions and 35 small onions.
This photo shows the 4 rows with onion plants at June 1. The onion sets planted next to the paving stones (blue arrow) resulted in small onions; less space and less nutrition there.
G)# Harvesting and cutting green leaves
You can harvest onions long before the leaves have dried on the garden soil.
- Pull onions out of the soil when the leaves are flopping over.
- Use scissors to cut the biggest part of the leaves.
- End up with 1 to 2 centimeters (0.5 to 1 inch) of foil.
- Lay the “cut off” onions in a big cardboard box.
- Put the box with onions at a dry (sunny) place to let dry.
- Turn the onions in the box when the upper sides of the onions are dry.
- After 1 or 2 days all sides of the onions are dry.
- Use a soft brush to wipe off the dry garden soil.
- Lay dried onions in an other cardboard box with the “stems up” (or “stems tilt up”).
- Don’t put too many onions in the box; there must be some free space around each onion.
- Let the onions dry in this box for about 1 week.
- Put the dried onions in another cardboard box.
- Put in many onions with stems up (or stems tilt up).
- Form only 1 layer of onions.
- When you put the box slanting, it is easier to put many onions with stems up (or stems tilt up) in the box.
- Many onions in the box with the stems up or tilt up.
- At dry weather, water the plants in the furrow 2 times per week (in the evening).
- When there is no hay or grass on the soil: Next day, loose the soil between the plants using a “hand trident”. At the same time, remove the weed and reshape the furrow.
- With hay or grass on the soil: No need for loosing the soil and reshaping the furrow. The hay or grass keeps the furrow in shape. Pull out small weed plants.
- Once a week, hoe between the rows.