Mums

Mums are in full swing now so I thought I would post some tips on when and how to pinch them. When I first started growing mums I found several sources of growing tips and thought I would share what I found.

I start mum planning in mid January and order rooted cuttings with tags from Raker (through Germania) in mid February for a June 1 delivery. By planning and ordering early Germania extends an early order discount (EOD) of 5%. In the past I have ordered the pinched version of the cuttings but have found it more cost effective for us to give the first pinch at transplant time. This also prevents the cuttings from filling in over the 4 weeks it takes to get all of them potted up.

During the planning phase I estimate how many sizes we're going to produce then calculate soil and pot cost for budgeting. We grow 3 "standard" sizes: 4", 8"x5" mum pans and 2 gallon. For calculating soil, here's my reference for fill rates:

4" Thinwall- 120
8"x5" mum pan - 28
Trade 2 gallon - 15

The 4" and 8" pots are from Dillen, the 2 gallon is a C600 from Nursery Supply Inc. Soil is Fafard 3B in 2.8 cu. ft. bags and fill rates have been calculate by me by filling and counting pots. I've used manufacure estimates before but have found those rates to differ from reality. We fill all pots to the very top, scrape off to level then lightly tamp in the soil a couple times.

When the rooted cuttings arrive the first thing we do after removing them from the shipping box is to water them and place them into a shady spot for a day. After being in a shipping box for several days I have found this step necessary to prevent unnecessary stress (and death) on the small plants. After that day I place them in the greenhouse and start a normal watering and feeding schedule.

Start planting your largest pots first as they'll take the longest time to grow. For me, I target having all the 2 gallon pots "all stuck up" by June 15, the 8" by the third week in June and the 4" no later than July 4th. I also stagger the 2 gallon planting by 1-2 weeks so there's a constant supply of finished product in September and October.

The basic sticking process is the same regardless of pot size, dampen the soil, dibble a hole in the middle of the pot then stick the rooted cutting in. At this point we pinch off the top 1/3rd of the cutting to stimulate side growth which helps yield a larger finished plant. Because it takes up to 4 weeks to get all of the cuttings planted the last round usually required half, if not 2/3, of the cutting to be pinched at sticking time.

For feeding we use a combination slow release & liquid program on the mums. At sticking all of them receive a top dress of Osmocote Plus 15-9-12 at the following rates:

2 gallon - 3 TBSP
8" mum pan - 2 TBSP
4" thinwall - 1 TBSP

Once planted up they are watered/fed in with 50ppm Nitrogen. We use a Dosatron injector system with Daniels plant food set and mixed to the 50ppm N level. Once planted up they are moved to an open production area where they are lined up pot to pot. They will eventually need to be spaced out to allow growth, but at the start I pack them together to help prevent them from falling over, especially in the rainy and windy part of June.

Now, the creator of the mums we purchase (Yoder - now owned by Syngenta) claims most of their mums are "no pinch" varieties. I have found this to NOT be the case. While modern varieties certainly require fewer pinches they are by no means "0 pinch".

When I first started growing mums the point at which to start pinching and how much to pinch was a cause of much confusion. Some papers stated to pinch every 2 weeks, others said to pinch when they outgrew the pot. The method I have settled in on is to watch when the roots touch the inside of the pot and starts to come out the drainage hole. Once you see the roots come out, give them the first pinch. Depending on the mum variety this can range from an extremely soft pinch to one almost axe like in nature. The end goal of this pinch is to remove most of the elongated stems to allow them to start "bushing out". If the variety is natually shrub-like in habit you won't need to remove much, just the new soft growth. However, if the variety is natually taller/longer you will need to pinch "to the pot". If the stems have grown beyond the pot they are in, pinch back "to the pot". Be sure to pinch the same amount from the top of the plant that you removed from the side. In the end, you should have a mostly round globe/ball shape.

Label the pots with the first pinch! I mark the back of the pot tag with the text "P1-mm/dd" to indicate the first pinch check occurred on that date. If a pinch was necessary, I place a check mark next to the text. The next time you want to check for a pinch is 2 weeks from that date. The second pinch, if necessary, should be quite soft and should remove the outermost new growth. At this point I again mark the tag with a P2 and the date. If they required a second pinch I put a check mark next to the P2. So, the back of our tags ends up looking like this:

P1-7/1 (check mark if it needed a pinch)
P2-7/15 (check mark if it needed a pinch)

While this might seem like a pain, it really helps out as your scouting to make sure the crop is on schedule and needs anything done to improve quality.

Many modern varieties do not require the second pinch so you will need to experiment a bit. Rarely, if ever, do they need a third pinch these days. Modern breeders, especially Yoder, has put a lot of effort into selections that require less pinching. In the long run this is a good thing as it dramatically lowers per touch labor cost.

Final spacing on the plants differs based on the pot size, however we use a basic method to get them close. As we lay out the plants for their final spacing, we use an empty pot of the same size between them to judge the distance. If they start to outgrow that space come August and September we then space them out so they're just barely touching each other. I like to space them out earlier in the growth cycle since you inevitably have to do this anyways. At the time of the first pinch we take them from the packed in area, pinch them then move them to a spaced growing section.

During active growth they receive the same feeding cycle that we use to water them in, a constant 50ppm N rate from the Dosatron. This, in combination with the Osmocote, yields nice large full plants that sell for a premium come fall. Images of our 2009 crop after the first pinch and final spacing are here. Happy growing!