Question
QUESTION: Hi there;

I live in Australia, and it's mid-spring and getting a lot warmer now!  I bought some little tomato plants (in individual plastic containers) a few weeks ago, and they seem to get a little taller each week.  Right now, they're around 4-6 inches in height and their roots are starting to dangle and drag out of the bottom of the containers.

a)  I'm just wondering, what is the ideal height to put them into a larger pot?  Should the pot be large?

b)  I got told the other day that once tomatos have been blown around at night by cold air, they're never going to be good.  For some odd reason, we've had a really cold fortnight (around 4 degrees Celsius at night and early morning), and I left the plants out in that for around 3 days until I bought a mini greenhouse for them.  Will they survive?  They don't SEEM any different, though they weren't growing as fast.  

Thanks!

ANSWER: Kay:
There is no height requirement for transplanting. If the roots are outgrowing the pot, it is time to transplant. When you do, repot the plant deeply - up to the bottom leaves if possible.

As for what you were told, it is nonsense. The person may have been thinking about the fruits or blossoms - cold temperatures will cause some internal damage, and blossoms will fall off. The plants WILL be damaged by frost however.

They sound like they are doing fine. Once the nighttime temperatures are consistently above 13 degrees C. they can be planted outside.

---------- FOLLOW-UP ----------

QUESTION: Hi Elyse

Thanks for the quick reply!  i've also read a lot of conflicting things on transplanting into pots; do you water the potting mix BEFORE you transplant and again after?  And what about potash / fertiliser, some people seem to suggest putting a little into the 'hole' you're going to transplant into (again before the actual transplant).  Would you recommend any of this?

Kay

Answer
Kay:
Yes, I always dampen the potting mixture before I transplant - in fact, I usually do it before putting the mix into the pots. This is to insure that 1)the medium is uniformly moist, and 2)to aid in filling the pot and reducing air pockets. Settle the soil by tapping the pot on the table, then add more if needed, put the plant in place and then backfill. Then water again, I usually do this from the bottom by putting the pot in the sink or another container with enough water to come up over the drainage holes. When the top surface is moist, then you know you have enough water.

As for adding fertilizer, it depends on your soil. I use liquid fertilizer in pots, and usually only feed once before planting out. If you are using granulated, I would mix it in with the medium, not just put it in the bottom of the container.

When planting the tomatoes out, it is helpful to add lime to the soil to prevent calcium deficiencies, which cause blossom-end rot, a common problem with tomatoes.

Elyse