Seedlings are growing in only some raised beds

Asked May 25, 2016, 10:43 AM EDT

I have 5 raised beds: 4x8 (x2), 4x4 (x2, but one of those is asparagus which never came up this year after 3 years), 2x4 (x1). The seeds I planted in the 4x8 beds are all growing better than those from the 2x4 and 4x4. These are all on the south side of the house and the sunlight is comparable (not identical) and the soil analysis is similar (which I can upload as pdf if necessary). The radishes were planted on 4/10 (over 6 weeks ago). The temperature has been colder than normal, but that shouldn't impact the radishes, bok choi, lettuce. I don't know what is causing this and would like to correct it before new plantings (melons, Brussel sprouts, ....). As you can see from the picture, the kale, spinach, and peas planted the same time as the radishes, lettuce, and bok choi are doing much better. They are in another box, but is that the relevant difference? Any help would be appreciated.

Middlesex County Massachusetts vegetables seed germination

5 Responses

There are a number of factors affecting seed germination, amoung them is the age of the seed. A simple test is to place 10 seeds between two damp paper towels, place them in a plastic bag and check them in 5 to 7 days. Asparagus seeds should be started in doors under grow lights. It is best to purchase 2 to 3 year old crowns when establishing an asparagus bed. One suggestion for improving your germination success is to cover them with a floating row cover,it will help maintain a more uniform temperature and prevent drying out of the bed caused by the wind.


I get it if they are not germinating, but that isn't the issue. For year old seeds I am actually planting more to counter the lower germination rate. The radishes, lettuce, bok choi, ... all start. It's that once they germinate the growth is incredibly slow or non-existent. I added the recommended amount of Nitrogen (blood meal) to all the beds so that shouldn't be it.

Would you like to see the soil analysis from UMass?

Other than spinach,which can germinate and grow when soil temperatures are in the mid 40's, most vegetables need a soil temperature in the 60's for adequate growth. This is the reason for the floating row covers.They will also extend your growing season in the fall.


So cooler soil temperatures could slow growth even after germination? Maybe the different box locations could lead to a small temperature difference (I would guess a couple of degrees at most, probably less). Would that cause such a vast difference between radishes, bok choi, beets, lettuce (all slow) vs. spinach, kale, peas, broccoli rabe (faster growers)? Is that the most probable differentiator?

Thanks for all of your help.


From the previous exchange, it seems fairly obvious that soil temperature is, indeed, a major factor in the poor growth rate of your vegetable plants.
If you have suitable space and the inclination, you may want to experiment with starting some of your seedlings indoors. Even then, you will discover that a seed-starting-heating-pad will enhance germination and early growth. Adequate light is also a necessity at this stage. Young seedlings, only 3 inches tall, can be hardened off and planted outdoors and covered with a floating row cover even before soil temperatures have reached the preferred 60 degrees. True, some of these seeds will germinate at temperatures as low as 40 degrees, they will not grow substantially until the soil temperature is much warmer.