really need help with watering!

kawaiineko_gardener(5a)April 15, 2013

I am trying to grow seedling transplants. I am using styrofoam blocks with holes in them; each hole holds a seed plug that is made of a soil less mix.

The light is about 4"-5" above the plants. I have the blocks directly on the heat mat. I am currently watering about twice a day (once in the morning, and once at night).

The middle of the soil plugs are moist, but the tops keep drying out. Is watering twice a day too fast?

If the rest of the soil is moist besides the top do I still need to water them, or will they be okay?

Basically I'd like to know if twice a day with watering when they're on the heat mat is overwatering. I don't use a humidity dome.

I know people recommend bottom-watering for seed starting, but whenever I try this the soil ends up too moist and the seeds either rot, or they germinate and I end up with this white fuzz on the stem of the seedling (the white fuzz isn't on the soil just the seedling that germinates).

Thank you for reporting this comment. Undo

I'm not sure if you're talking about un-germinated seeds or small plants (seedlings). You mentioned that the light was 4 or 5 inches above the 'plants'. But also said that you have the blocks on the heat mat (which would suggest un-germinated seeds. ???


    Bookmark   April 15, 2013 at 6:19PM
Thank you for reporting this comment. Undo

Stop watering so much. You are going to get damp off. Think of it--where are the roots. They are not on top. Soil dries from the top down. When it's dry on top there is still plenty of moist soil around the roots. There are little air pockets in soil that roots need to grow right. When you water those air pockets fill with water which is fine if you allow them to dry out and the air pockets return.

When you bottom water and your soil gets soggy you are not allowing the soil to dry before you water again. A plant will recover in short order from a wilt from lack of water but may never recover from being overwatered.

There are 2 ways to determine when you need to water. The first is to stick your finger in the soil and feel for moisture. Obviously you can't do that with your plugs but it is good for pots or testing the garden. The next is weight. A dry container is much lighter than one with moisture.

When germinating on a heat mat humidity domes are used to keep the moisture around the seed. Since the seed is on top of the soil and needs moisture to germinate the domes keep the seed moist without adding extra moisture. If your plants have germinated take them off the heat mat. They don't need it.

Another thing--lower your lights. They should be no more than an inch away from the lights. The plants are not getting the full benefit of your lights being so far away

I hope this helps

    Bookmark   April 15, 2013 at 6:37PM
Thank you for reporting this comment. Undo
digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

If we have said it once on this forum we have said it one hundred times.

1) heat mats and domes are for germination only, NOT for seedlings once germinated.

2) Lights should be no more than 1-1 1/2" above the plants unless they are T5 bulbs, then 3-4 inches.

3) the surface of the soil is NOT a valid indication that watering is needed.

The foam blocks and sponge plugs are also for germination only, not growing. They need to be transplanted into pots of potting mix as soon as possible after germination. They are sponges and like any sponge they hold too much water and then dry out too fast for proper plant health. So if you use then get them into potting mix ASAP.


    Bookmark   April 15, 2013 at 6:49PM
Thank you for reporting this comment. Undo

Yes I"m referring to seeds that haven't germinated yet, not seedlings. I know what heat mats are only used to aid in faster germination. I turned the heat mat off today because some of the cool weather seeds I planted have started to sprout.

If the surface of the soil doesn't indicate whether watering is needed, what does? I already checked the middle of the plugs, and they are moist.

When I try to use the domes it ends up making the soil too wet.

I asked the company I got the grow light from how far above the plants the lights should be and they recommended 4"-6"; it's a high output florescent bulb. No it's not a normal florescent bulb, I called the seed company to verity this.

    Bookmark   April 16, 2013 at 3:38PM
Thank you for reporting this comment. Undo

I did not see that you are using a dome to keep moisture on the top while the seeds germinate. If not, I just use plastic wrap over the plug trays till germination. Once they germinate, take off the plastic. The "fuzz" you are getting on the new shoots is fungi from overwatering once the roots start growing in the really damp soil. As for the lights, even with HO bulbs, they still need to be closer than 6". Your little seedlings will streatch and get leggy trying to reach the light. The company you got them from is concerned with the amount of heat produced from HO bulbs. To reduce the heat, get a cheap fan or two to blow across the top of the light fixture. As was stated earlier, the easiest way to determine if watering is needed after germination is by the weight of the plug tray. If it is light, bottom water. If it is still "weighty", don't water. If it makes you feel better, you can mist the top of the soil, but once the seedlings emerge, their water is coming from deeper in the plug cells.

    Bookmark   April 16, 2013 at 4:03PM
Thank you for reporting this comment. Undo

If you find it difficult to know when to water your seeds or seedlings, consider purchasing an inexpensive moisture meter; they work just fine. Usually, I just go by the weight of the container but sometimes I do use my moisture meter (especially with larger containers). I paid less than $15 for mine (Rapitest brand) but you can actually get them for less than that :-)

If you could get used to using the dome, I think you would like it and have a lot less watering problems. When you use the dome, you should see a very slight amount of condensation on the underside of it. If the condensation is running down the side of the dome you have too much water, remove it for awhile. Actually, once you get it right, you normally don't have to water anymore at all until the seeds have germinated and the dome (and heat mat) have been removed.

But if you still feel uneasy about using the dome, do consider the moisture meter idea.

Hope this is helpful,


    Bookmark   April 16, 2013 at 8:36PM
Thank you for reporting this comment. Undo
digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

I already checked the middle of the plugs, and they are moist.

That's your answer. If the middle of the plugs are moist then they don't need water. In pots of soil you stick your finger down into the soil. With sponge plugs you have to check the plug at the root level.


    Bookmark   April 16, 2013 at 10:19PM
Thank you for reporting this comment. Undo
runswithscissors(MT 4/5)

One tool that has been helping me with this problem lately is a pump sprayer. It just mists the tops where seeds are needing moisture to sprout, but doesn't provide enough water to saturate on down. I've been misting daily and only watering when the container gets lighter. It seems to be helping altho I don't have it down to a science yet.

    Bookmark   April 17, 2013 at 12:33AM
Sign Up to comment
More Discussions
Recommendations for seed starting medium please
I started gardening for fun about 2 years ago. I have...
Need Advice........
I sowed flats of New Guinea Imps & Begonias 3 weeks...
mail order seeds
I purchased from Gurney Seed and Territorial Seed Co...
Make your own seed tapes
Something to do on a cold Feb. day make your own seed...
When seeds go bad
I've been starting plants indoors over winter for several...
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™